Beyond Apollo

Landing Soyuz in Australia (1993)

2012-01-27T17:21:00.000-08:00

All images in this article are courtesy of NASA. The Australia map is a modified version of one in report JSC-34045.
Kosmos 133, the first in the long line of Soyuz ("Union") spacecraft, lifted off unmanned from Baikonur Cosmodrome in Central Asia on November 28, 1966. Its mission: to dock automatically with Kosmos 134, another unmanned Soyuz that was scheduled to be launched the following day.

The new spacecraft included three modules. These were, from aft to fore, the cylindrical service module containing the spacecraft's main rocket engine; the cramped descent module, designed for land landing, which included the main control panel, heat shield, main and backup parachutes, soft-landing rockets, and three cosmonaut launch and landing couches; and, linked to the descent module by a hatchway, the ovoid orbital module, which contained extra living space and included a docking unit. The three modules had a combined mass of about 7000 kilograms.

During reentry, the orbital and service modules would separate from the descent module and disintegrate high above the Earth. The 2900-kilogram descent module would blaze through the atmosphere, rolling about its center of gravity to generate lift and reduce the deceleration its crew would feel. About 11 kilometers above the Earth, the module would deploy its twin drogue parachutes, then its single main parachute would open (bottom image above). Just before landing, it would ignite its solid-propellant soft-landing rockets, then it would bump down within a recovery zone east of Baikonur.

Any joy flight controllers in Moscow felt as Kosmos 133 soared above the Earth vanished when they found that its attitude control system did not work properly. They called off the Kosmos 134 launch. Several times they tried to orient Kosmos 133 so that its main engine pointed forward in preparation for retrofire and reentry. On November 30, they commanded the first Soyuz to self-destruct when it appeared that it would land in China, far downrange from its intended recovery zone.

When reporting on the half decade that followed Kosmos 133, it needs less space to describe Soyuz and Soyuz-derived spacecraft successes than it does to list their failures. Kosmos 186 and 188 successfully performed an automated docking in late October 1967, and Kosmos 212 and 213 repeated the feat in April 1968. In January 1969, the manned Soyuz 4 and 5 spacecraft docked and two cosmonauts spacewalked between them. Zond 7, a prototype manned circumlunar Soyuz variant without an orbital module, flew unmanned around the moon and landed as planned in the Soviet Union in August 1969. The two-man crew of Soyuz 9 remained aloft for nearly 18 days in June 1970, breaking the space endurance record Gemini VII had set in 1965.

These scattered successes should not obscure the fact that, of the 16 individual cosmonauts launched on Soyuz between 1967 and 1971, one-quarter lost their lives. Of the more than 30 Soyuz-derived spacecraft launched in that same period, all but nine failed in some significant way.

Following the deaths of the three Soyuz 11 cosmonauts after they undocked from the Salyut 1 space station on June 29, 1971, Soyuz underwent a major redesign. When manned Soyuz flights resumed in September 1973, it could carry no more than two space -suited cosmonauts. Soyuz spacecraft suffered more malfunctions in the 1970s, often failing to reach their space station targets, but no more cosmonauts died.

The 1977 advent of the highly reliable Progress Soyuz variant, an automated cargo ship for resupplying space stations, marked a break from the past for Soyuz. Malfunctions tailed off and, after a dramatic launch pad booster explosion in 1983, no Soyuz failed to dock with its space station target. Even the pad explosion could be seen as a sign of design maturity; despite suffering damage, the Soyuz escape system saved its crew.

Technology upgrades produced first the Soyuz-T and then the Soyuz-TM variants, which could transport up to three space-suited cosmonauts. By the early 1990s, Soyuz had developed a reputation for simple, sturdy reliability.

Even before the Soviet Union collapsed in 1991, officials with the Soviet aerospace enterprise NPO Energia began to peddle their wares, including Soyuz, at major international aerospace meetings. An implied subtext of these promotional efforts was that, if the West would not buy products from the financially strapped Soviet aerospace sector, then its engineers might sell their technical expertise to countries opposed to Western interests. The threat - and promise - of Soviet/Russian space technology soon attracted the attention of the U.S. government. Spaceflight thus entered the geopolitical arena in a way it had not since the mid-1970s, when the 1975 Apollo-Soyuz Test Project (ASTP) became the poster-child for President Richard Nixon's policy of detente.

In December 1991, Congress directed NASA to study the feasibility of using the Soyuz-TM as a low-cost "lifeboat" or "escape pod" for its planned Freedom space station. The concept of a space station lifeboat was an old one, dating back at least to the 1960s. NASA had acknowledged the need for such a vehicle soon after the January 1986 Challenger accident killed seven astronauts and grounded the Shuttle fleet for almost three years.

NASA foresaw three scenarios in which a lifeboat might save lives. First, a medical emergency on board Space Station Freedom might require rapid evacuation of a sick or injured astronaut. Second, a disaster on the station - for example, a fire - might render it uninhabitable. Finally, another Shuttle accident might ground the Orbiter fleet, stranding a crew on the station without resupply.

By early 1992, NASA had offered up several designs for an Assured Crew Return Vehicle (ACRV), as it called its planned Freedom lifeboat (see link below). Unfortunately, even the simplest would cost at least $1 billion to develop. It would, after all, constitute a new piloted spacecraft designed to remain docked to Freedom for years, dormant but always ready.

As part of the preliminary Soyuz-TM ACRV feasibility study for Congress, NASA engineers traveled to Moscow in March 1992 to meet with Russian government and NPO Energia officials. The agency completed its study the following month. In its study report, NASA portrayed Soyuz-TM as an interim lifeboat useful during the period when Freedom's crew numbered no more than three. Soyuz-TM would, it was hoped, move closer the day when Freedom could be continuously staffed. In about the year 2000, as Freedom's population grew to six or eight astronauts, an "optimized" U.S.-built ACRV would take over from Soyuz.

On June 17, 1992, U.S. President George H. W. Bush and Russian President Boris Yeltsin signed agreements in Moscow providing for a broad range of cooperative space ventures. A Russian cosmonaut would fly on board the U.S. Space Shuttle, a U.S. astronaut would live on board the Russian Mir space station, and a Shuttle Orbiter would dock with Mir. The following day, NASA and the Russian Space Agency signed a $1-million contract by which the two space agencies agreed to jointly assess Russian space technology, including Soyuz-TM, for use in NASA's programs.

It had, of course, already become obvious that Soyuz-TM would need modifications to make it an ACRV for Freedom. Most mundane, perhaps, its Russian control panel labels would need to be replaced with English. More important, its on-orbit endurance would need to be stretched from 180 days to three years and its docking unit would need to be made compatible with Freedom's docking ports. In addition, NPO Energia would need to find a way to squeeze NASA'S tallest astronauts into its already cramped descent module.

Even more challenging was the matter of Freedom's orbit about the Earth. NASA planned to assemble its station in an orbit inclined 28.5° relative to Earth's equator. A Shuttle Orbiter launched due east from Kennedy Space Center, located on Florida's east coast at 28.5° north latitude, could in theory reach Freedom bearing its maximum possible payload. The station would orbit over areas on Earth's surface within a equator-centered, globe-girdling band spanning from 28.5° north to 28.5° south latitude.

Freedom's orbital inclination meant that Soyuz-TM could not reach it from Baikonur Cosmodrome if it were launched on the normal Soyuz launch vehicle (top image above). The sprawling launch complex was located at 51.6° north, so a spacecraft launched to Freedom would need to change its orbital plane by a whopping 23.1° to effect a rendezvous. Each degree of plane change would demand hundreds of kilograms of propellants. If the Soyuz-TM ACRV was to be launched to Freedom from Baikonur, then the larger, more powerful, and more costly four-stage Proton booster would need to do the job. Its entire fourth stage, suitable for launching spacecraft out of Earth orbit toward the moon and planets, would be expended in making the plane change.

NASA envisioned that a Shuttle Orbiter would deliver the unmanned Soyuz ACRV to Freedom, where Orbiter or station robot arms would berth it at a waiting docking port. Alternately, the Soyuz ACRV might launch unmanned on a U.S. expendable rocket and perform an automated rendezvous and docking with Freedom.

Freedom's 28.5° orbit would also affect where the Soyuz ACRV could land. In a June 1993 report, the ACRV Project Office at NASA Johnson Space Center in Houston summed up its study of potential Soyuz ACRV landing zones. It noted that a Soyuz ACRV could land on U.S. soil only in south Texas or south Florida, where suitable landing areas were small. (The report made no mention of Hawaii, the most southerly of U.S. states, though it also would be largely unsuitable.)

The ACRV Project Office then looked abroad to countries with wide-open spaces. Australia appeared ideal. The northern two-thirds of the country lies between 28.5° and about 10° south latitude, and much of its interior is flat, arid, and sparsely populated.

As part of the June 1992 $1-million contract, NASA engineers and officials, a U.S. State Department representative, and NPO Energia engineer Valentin Ovciannikov traveled to Australia in November 1992 to conduct a preliminary assessment of four potential Soyuz ACRV landing zones. The Australian Space Office (ASO), working with the Australian Geological Survey Organization and the National Resource Information Center, selected the zones based on NPO Energia and NASA selection criteria.

The landing zone survey team stopped first on November 9 in Australia's capital, Canberra, to meet with government officials. NASA expected that Australia, a signatory of the 1967 United Nations "Agreement on the Rescue of Astronauts, the Return of Astronauts, and the Return of Objects Launched into Space," would stand ready to assist space travelers forced to land in its territory. They found tentative support for their plans, though the Australians made it clear that they would approve nothing until they had a nation-to-nation treaty covering responsibility for costs and damages.

On November 11, the team began a whirlwind eight-day, 5300-nautical-mile tour of the proposed landing zones. Team members flew first to Adelaide, capital of South Australia. There they met with state police to describe the Soyuz ACRV mission and learn about Search and Rescue (SAR) capabilities in the Coober Pedy-Oodnadatta region. Coober Pedy, "the opal capital of the world," is a town with a population of about 2000 located in the Australian Outback about 460 nautical miles north of Adelaide.

The team learned that the police were responsible for SAR operations throughout Australia, and that Australian SAR personnel and equipment were concentrated in capital cities, not scattered among small Outback communities. In South Australia, the state police had four elite rescue teams and three small airplanes that could reach Coober Pedy's 4633-foot-long asphalt runway from Adelaide in two and a half hours. They rented a single helicopter that could reach the area in four hours.

The next day (November 12), the team flew to Coober Pedy in a small chartered plane. They learned that Coober Pedy police and mine rescue had at their disposal several four-wheel-drive vehicles and an ambulance, and found that much of the area was dry and flat with red, gravel-covered soil of good bearing strength. The hard surface would enable four-wheel-drive vehicles to reach points throughout the area and would help to ensure that the Soyuz ACRV landing system would operate properly.

As an aside, the team noted in its June 1993 report that NASA could learn a great deal by participating in a Soyuz-TM landing. NASA engineers subsequently observed the Soyuz-TM 16 landing in Kazakstan on July 22, 1993. It was an appropriate landing for them to observe; Soyuz-TM 16 tested a Russian-built APAS-89 androgynous docking unit of the type U.S. Shuttle Orbiters would use to dock with Mir during the Shuttle-Mir missions (1994-1998). The APAS-89 system, which was based on the U.S.-Soviet APAS-75 system used for ASTP, had been built originally for Soviet Buran shuttle dockings with Mir.

In the south part of the Coober Pedy zone, the survey team gathered data on the "moon plain," a large area where trees - gidgee and acacia - grew along dry watercourses and the soil had "fair to poor" bearing strength. They also noted a field of small sand dunes. NPO Energia's Ovciannikov worried that the Soyuz ACRV descent module might roll between two dunes and became stuck with its top-mounted crew hatch buried in sand. Using a hand-held anemometer and historical weather data from the Australian Bureau of Meteorology, the team determined that wind speeds near Coober Pedy would be acceptable for Soyuz ACRV landings.

The team spent the night in Coober Pedy listening to the distant howls and barks of dingos, then flew on to Perth, the coastal capital of Western Australia. On November 13 they discussed with state police the SAR capabilities in the area of Meekatharra, about 770 miles to the northeast. They learned of the Royal Flying Doctor Service (RFDS), which had one of its 14 bases in Perth. RFDS provided rapid medical response to two-thirds of the Australian continent, including all four of the candidate landing zones. In their trip report, the team advised NASA doctors to begin to coordinate with the RFDS as soon as possible.

The police in Perth made it clear that current local needs had priority over future NASA needs. They asked to be alerted 24 hours before an expected Soyuz ACRV landing. In its report, the team noted that this would not be possible for a medical evacuation or an emergency station evacuation, though it would be possible for a crew returning from Freedom during a Shuttle stand-down.

The team flew to Meekatharra on November 14. Of great interest to the team was a 7156-foot-long, 150-foot-wide asphalt runway at the Meekatherra Airport. In their report, the team suggested that the runway, built for emergency 707 landings, might be used to land cargo planes bearing rescue equipment, four-wheel-drive vehicles, and helicopters.

The team judged that Meekatherra's soil was of "excellent" bearing strength. Acacia and mulga trees stood over less than 10% of the area, which was very flat. There were, however, scattered bedrock outcrops protruding from the windswept plain. In addition to presenting a minor impact hazard, the outcrops included naturally radioactive "uraniferous" deposits. Ovciannikov expressed concern that these might interfere with the descent module's altimeter, which relied on a radioactive source. (Rescuers would need to "safe" the source before they could extract astronauts from the descent module.)

Meekatharra is only about 300 miles from Australia's west coast, a fact that had both pluses and minuses for Soyuz ACRV landings. On the one hand, it meant that debris from the discarded orbital and service modules would not fall on land. On the other, it could lead to a splashdown if the descent module followed a ballistic trajectory; that is, if its guidance computer malfunctioned so that it did not roll about its center of gravity to create lift. The Soyuz-TM descent module was designed to float, but a splashdown would complicate crew recovery. Following a ballistic reentry, quick crew recovery could be crucial; the ballistic reentry could subject the crew, which might be deconditioned after a long stay in weightlessness, to deceleration equal to 10 times the Earth's surface gravity.

The team flew on to Darwin, capital of the Northern Territory, on November 15. There territorial police described their 30-member Police Task Force, which was trained to deal with situations as diverse as riot control, bomb disposal, and cliff rescue.

The proposed Soyuz ACRV landing zone in the Northern Territory, the largest of the four candidate zones, was centered on the town of Tennant Creek (population 3200). The territorial police explained that their SAR resources were based both in Darwin, 600 miles from Tennant Creek, and in Alice Springs, 300 miles away.

The team visited the Tennant Creek zone on November 16. They learned that the Tennant Creek police force included 25 officers but only one four-wheel drive vehicle. As at other sites, the police worried that the Soyuz ACRV soft-landing rockets might start brush fires. NPO Energia's Ovciannikov assured them through an interpreter that they would not.

The team noted that the region was in the sprawling Barkley Tableland, a region of black-earth raised plains covered with gold-colored Mitchell grass. Ovciannikov noted that it resembled the Soyuz-TM "landing grounds" around Dzhezkazgan, Kazakstan.

Unlike the other landing zones, Tennant Creek had distinct wet and dry seasons, with the former occurring in the southern-hemisphere summer/early autumn months (December through March). Located just 19.5° south of the equator, it was also the hottest of the four zones, with an average of 22 days per year above 40° Celsius (104° Farenheit). Flooding from seasonal rains would not interfere with a Soyuz ACRV landing, but it might impede surface vehicles dispatched to recover the astronauts.

The team flew to Charleville in Queensland on November 17 without stopping in Brisbane, the state's coastal capital, and conducted their landing zone survey the next day. They found that the airport in Charleville included two asphalt runways, the largest of which was 5000 feet long and 100 feet wide. Though they met with local police, the team's report on the Charleville zone included no SAR data.

Charleville's rolling plains, or downs, differed from the other zones surveyed in that they included many large trees (briglow and sandalwood) interspersed with "square" and "circle" treeless areas used for grazing and farming. Charleville police told the team that local ranchers and farmers knocked down and burned the trees to create grazing land, but that they grew back within a few years.

Ovciannnikov compared Charleville to the "wooded steppe" on the north edge of the Soyuz-TM landing zone near Arkalyk, Kazakstan. The open areas would be acceptable landing sites, though the bearing strength of their black and brown loamy soils was rated only "fair."

The team returned to Canberra late on November 18. After another meeting with Australian government officials, during which they signed a document that summarized what the parties had learned and what had been agreed, its members departed Australia on November 20, 1992.

Shortly before the team began its Australian tour, U.S. voters had gone to the polls, where they had favored Democrat William Clinton over incumbent George H. W. Bush. Many in NASA feared that, after he took office in January 1993, Clinton would not support the Space Station. With no Station, their reasoning went, the Shuttle would lose its purpose, and U.S. piloted spaceflight would end.

On March 9, 1993, however, President Clinton ordered NASA to produce three new cost-contained space station designs in 90 days. The President, aided by an advisory committee, would then select one design for continued development. On March 25, Vice President Al Gore appointed the Advisory Committee on the Redesign of the Space Station, chaired by MIT's Charles Vest.

That same month, in a letter to NASA Administrator Daniel Goldin, Russian Space Agency director Yuri Koptev and NPO Energia director Yuri Semenov proposed what would become the NASA station program's salvation: a merger of the financially strapped, politically troubled Freedom and Mir-2 programs. They proposed that the joint station be assembled in an orbit inclined more than 50° relative to Earth's equator. The following month, the Russians provided NASA with a straw-man assembly sequence for the joint station.

On May 11, 1993, Vest advised the White House that, regardless of the design selected, the U.S. station should be built in a "world orbit" inclined between 45.6° and 51.6° so that Russian - and Japanese and Chinese - rockets and spacecraft could easily reach it. This would, he explained, ensure that redundant means of reaching the station would exist. He added that "the shuttle will likely be grounded again during the operational life of the station."

Vest presented the Advisory Committee's report to the White House on June 10, 1993. Barely two weeks later, on June 23, the station had a near-death experience; the U.S. House of Representatives approved Fiscal Year 1994 station funding by a margin of a single vote (215-216). The vote, which showed how politically vulnerable the station had become, clearly conveyed to NASA that major reforms in the station program were essential.

President Clinton soon approved Option A, or Alpha, the U.S. station design most like Freedom. Even as Clinton demonstrated his commitment to piloted spaceflight, the proposal to merge the U.S. and Russian station programs gained momentum. Engineers and managers in Moscow, Washington, and Houston began to refer to "Ralpha," which was short for "Russian Alpha."

On September 2, 1993, Gore and Russian Prime Minister Viktor Chernomyrdin released a joint statement on U.S.-Russian space cooperation. In it, they announced a dramatic expansion of the cooperation outlined in the June 1992 Bush-Yeltsin agreement. Though controversial in some quarters, the expanded Russian role reinforced the geopolitical justification for the space station, helping to ensure that Congress would support it.

In November 1993, NASA and the Russian Space Agency completed an addendum to NASA's August 1993 Alpha Station Program Plan. It amounted to a preliminary blueprint for merging the U.S. Alpha and Russian Mir-2 programs. The resultant International Space Station (ISS) would be assembled in a 51.6° orbit.

The 51.6° ISS orbit meant that NASA no longer needed Soyuz ACRV landing zones in Australia. Soyuz spacecraft that docked at the ISS could land in their normal recovery zones in central Asia, or in backup zones in the U.S. Midwest and Great Plains. (These had existed, apparently without U.S. knowledge, since the 1970s.)

Even before ISS moved from proposal to plan, some in NASA had resigned themselves to using Soyuz-TM-based ACRVs indefinitely. The ACRV Project Office survey team's final report on its Australia trip assumed that, as Freedom's population grew, NASA would buy more Soyuz ACRVs from NPO Energia. It also assumed, however, that each would remain docked with Freedom for three years to minimize the number of Soyuz ACRVs that NASA would need to buy.

In practice, Soyuz spacecraft launched to the ISS reverted to the pattern they had followed during the Mir station program. A crew would arrive in a Soyuz, which would then remain docked to the ISS. If they faced an on-board calamity, the crew could evacuate in their Soyuz. If all went as planned, however, they would land in central Asia after a mission lasting about six months, a period dictated by both crew and Soyuz-TM endurance.

A U.S.-built station lifeboat remained a NASA goal, in large part because it might - like Soyuz - serve also as a small crew transport spacecraft. It could thus partially replace or augment the Space Shuttle. In the mid-to-late 1990s, the favored design was a lifting body. For much of the past decade, NASA has favored an Apollo look-alike capsule.

NPO Energia, meanwhile, redesigned the Soyuz-TM interior to produce the Soyuz-TMA, several of which are shown in the images above. First flown in 2002, it can accommodate taller members of the U.S. astronaut corps.

Soyuz-TMA was the only ISS crew transport during the 29 months following the February 1, 2003 Columbia accident. In July 2011, President George W. Bush's January 2004 order to retire the Shuttle fleet when ISS assembly was completed took effect. By then, the Shuttle's absence no longer meant that Soyuz-TMA was the only means of transporting crews to and from the ISS, for Russia had begun manned test flights of the modernized Soyuz-TMA-M. The new Soyuz variant includes a lightweight computer, digital avionics, and improved displays. Soyuz-TMA 22, scheduled to return from the ISS in March 2012, is the last spacecraft in the Soyuz-TMA series.

http://beyondapollo.blogspot.com/2010/10/quick-to-escape-pods-1986-1992.html

Alpha Station Addendum to Program Implementation Plan, RSA/NASA, November 1, 1993.

Australian Landing Sites Evaluation and Survey, JSC-34045, Assured Crew Return Vehicle (ACRV) Project Office, NASA Lyndon B. Johnson Space Center, June 22, 1993.

Assured Crew Return Vehicle (ACRV): Technical Feasibility Study on Use of the Soyuz TM for the Assured Crew Return Vehicle Missions, JSC-34038, Assured Crew Return Vehicle (ACRV) Project Office, NASA Lyndon B. Johnson Space Center, June 1993.

Letter with attachment, Charles M. Vest to John H. Gibbons, May 11, 1993.

Mir-Freedom Assembly Sequence, NPO Energia, April 1993.

Letter, Y. Koptev and Y. Semenov to D. Goldin, March 16, 1993.

Assured Crew Return Vehicle (ACRV): Preliminary Feasibility Analysis of Using Soyuz TM for the Assured Crew Return Vehicle Missions* *Includes Evaluation of Automated Rendezvous and Docking System, JSC-34023, Assured Crew Return Vehicle Project Office, NASA Lyndon B. Johnson Space Center, April 1992.

50-man Space Base crew (1970)

2012-01-24T18:52:00.000-08:00

When Thomas O. Paine became Acting Administrator of NASA following the October 1968 resignation of James Webb, he had seven months of Federal job experience. After Richard Nixon was sworn in as President in January 1969, Paine became a Democrat in a Republican Administration. He submitted his resignation pro forma, but the Nixon White House asked him to stay on.

Paine's political position was pitifully weak, and savvy observers must have seen his retention as a commentary on the Nixon Administration's enthusiasm for space. Paine, however, behaved as though he had the new president's unstinting support. Hoping to build on the anticipated success of the first Apollo moon landing, he pushed for an ambitious new post-Apollo space program. Though told by Nixon's Office of Management and Budget that NASA's budget would be capped at $3.5 billion in Fiscal Year (FY) 1971, he stubbornly requested $4.5 billion. He stated publicly that he would seek a $5.5-billion NASA budget in FY 1974.

Despite clear signals from the Nixon White House that grand space plans would not find support, Paine urged his center directors to "think big." Among his goals was a 12-man space station by 1975 that would lead to a $10-billion station with a crew of 100 by 1980 (images above). His big space station, known as the Space Base, was a key component of NASA's Integrated Program Plan, which also called for upgraded Saturn V rockets, a fleet of reusable winged Earth-to-Orbit Shuttles, a fleet of nuclear-powered cislunar Shuttles, a moon-orbiting space station, a lunar surface base, and, by 1986, a manned mission to Mars.

A January 1970 paper by NASA Marshall Space Flight Center engineer Georg von Tiesenhausen captured the flavor of space planning under Paine. In it, von Tiesenhausen attempted "to establish a baseline social and functional structure for a 50-man Space Base" in order to avoid "problems pertaining to organization, population structure, and discipline."

Von Tiesenhausen split the all-male Space Base population into three groups. The Base Command and Management Group would include seven men: the Space Base Commander, the Deputy Commander for Operations, and the Deputy Commander for Science. The Deputy Commander for Operations, the Space Commander's first deputy, would have under him four directors; these would oversee logistics, communications, maintenance, and personnel. The Deputy Commander for Science would be third in the Space Base chain of command.

Eighteen men in three subgroups would make up the Base Operations Group. Subgroup 1, with six men, would tend to Space Base communications, navigation, and data handling functions. The eight men of Subgroup 2 would take care of Space Base power, central computer, life support, and general maintenance functions. Subgroup 3 would include two flight controllers and two medical doctors.

The Deputy Commander for Science would oversee a Scientific Faculty of 25 men. This would include eight Ph.D. scientists, 11 scientific assistants, three technicians, and three "others" arrayed in three discipline subgroups. Subgroup 1, with eight men, would study astronomy, physics, and materials science; Subgroup 2, also with eight men, would focus on biological sciences; and Subgroup 3, with nine men, would take in Earth resources observation and miscellaneous disciplines. Von Tiesenhausen expected that the Scientific Faculty would include mainly men who were not professional astronauts.

He then organized his Space Base crew into three shifts. The day shift, with 21 men, would be headed up by the Space Base Commander. The Deputy Commander for Operations would head up 17 men in shift 2, and the Deputy Commander for Science would supervise 12 men in shift 3. This shift pattern would be followed six days out of seven. The seventh day, a "rest day," would see minimal staffing (five men per shift). Scientific Faculty members would also plan their schedules to accommodate observation and experiment opportunities.

With his crew structure and schedule serving as a point of departure, von Tiesenhausen apportioned territories within the Space Base to the various groups and subgroups. His cardinal rule was that "activities with close relationships and interfaces. . . be located within specific segments of the Base, thus requiring a minimum of traffic."

Three rotating artificial-gravity modules would each serve as a segment, and the "rotating hub" of the Space Base, where the arms supporting the artificial-gravity modules would meet, would divide the zero-gravity center section into two segments. Von Tiesenhausen designated the center segments C1 and C2 and the rotating module segments R1, R2, and R3. The former would provide 4500 square feet of living and working space, while the latter would provide 5900 square feet.

C1 would contain the "docking and supply terminal" for arriving spacecraft, science labs, and half of the Command and Management area. The smaller C2 zone would include half of the Command and Management area and Base Operations. C2 was positioned so that a passageway leading from Base Operations could provide direct access to the Space Base nuclear reactor.

R1 would contain "subsystems," while R2 would provide living quarters for the Command and Management Group and Base Operations Group. The Scientific Faculty would live in R3, but would have duplicate quarters in C1 so that they could remain close to their experiments. Von Tiesenhausen contended that this arrangement could also mitigate "the possible ill effects of alternating between the weightless state and the artificial weight state," which, he wrote, might "be most pronounced with untrained scientists."

The rotating and center sections would each include a sickbay and a "document center." The center section would also include a 20-man dining room, a 20-man assembly hall, and three toilets with showers. All three artificial-gravity modules would include a toilet with shower, and R2 and R3 would each include a 10-man dining room and a 10-man assembly hall.

Even as von Tiesenhausen's paper saw print, the Nixon Administration unveiled its FY 1971 Federal budget. NASA's eventual portion was $3.38 billion, down from $3.75 billion in FY 1970. In the January 1970 press conference on the FY 1971 NASA budget, Paine announced that the Saturn V production line, on standby since 1968, would be permanently closed. Nixon accepted Paine's resignation in July 1970.

Fifty-Man Space Base Population Organization, NASA Technical Memorandum X-53989, Georg von Tiesenhausen, NASA Marshall Space Flight Center, January 31, 1970.

From the author: a new blog

2012-01-16T08:24:00.000-08:00

In the past month and a half, I have been posting alternate history on Beyond Apollo (BA). This has made me a trifle uncomfortable, because I want BA to be seen as a serious space history blog, and alternate history is often lumped into the broad category of science fiction & fantasy. I dearly love much science fiction & fantasy, make no mistake (you should see my Doctor Who curtains), but there's a time and a place for everything.

I think that there are two basic kinds of alternate history. Narrative alternate history follows conventional fictional forms. It includes a plot, characters, and dialog. Analytic alternate history, on the other hand, reads as an essay or article. The former can be grouped with science fiction & fantasy, but the latter is harder to classify.

The alternate history I posted on BA falls into the analytic category. I hope that it can grow to become a solid alternate history of the space age that would, for those unfamiliar with real space history, be convincing enough to be accepted as a real history of the space age. I take as my model Robert Sobel's classic alternate-timeline history textbook For Want of a Nail: If Burgoyne had Won at Saratoga.

I also take as models two other classic books that were not alternate history when they were published, but which have become alternate history with the passage of time. These are Kerry Mark Joëls' 1985 The Mars One Crew Manual, which describes the 1996 international Mars One mission, and Ben Bova & Pat Rawlings' 1987 Welcome to Moonbase. In the latter, the U.S. completed the first permanent manned space station in 1998, the Soviet Union landed men on the moon in 1999, and the U.S. returned to the moon in 2001. December 2003 saw the first Christmas celebrated on the moon and, in the present year, a nine-man expedition to locate ice at the moon's north pole will fall afoul of a massive solar flare.

I state all this as preamble to an announcement: Beyond Apollo will henceforth include no alternate history. If you are inclined to be alarmed, please do not be, for I have just launched a new blog dedicated to space-age alternate history. It's called, not very creatively, Alternate History of the Space Age. That's a mouthful, so in the spirit of those space-age acronyms we all know and love, we can call it AHSA for short.

http://alternatehistoryofthespaceage.blogspot.com/
Unfortunately, when I moved the five recent alternate history posts from BA to AHSA, I lost the 130+ comments they generated. I hope that my clumsiness will not discourage you from posting comments in the future. Some of you might even wish to reconstruct your comments over on the new blog.

Onward and upward, like our little friend in the picture at the top of this post. Please watch this space; but please also watch my new blog, Alternate History of the Space Age.

The PH-D Proposal (1978, 1981)

2012-01-15T17:13:00.000-08:00

Artwork © Don Dixon/Cosmographica.com).
Used by permission.

S. Fred Singer predicted in 1956 that the Earth's magnetic field would be found to capture radiation from the Sun. This anticipated the 1958 discovery of the Van Allen radiation belts. Singer first wrote about piloted missions to the two small martian moons while serving as a spaceflight advisor to President Dwight Eisenhower. In a February 1960 letter to the journal Astronautics, he came out in support of Soviet scientist Iosif Shklovsky's imaginative theory that Phobos and Deimos were hollow structures built by Martians. Singer suggested that the moons were meant "to sweep up the radiation belts around Mars so as to enable Martians to operate without radiation hazards in the vicinity of their planet." Singer added that Phobos, Mars's inner moon, "would make an ideal space base for manned exploration of Mars."

In a small NASA-funded study conducted in 1977-1978, Singer revisited this last concept. By his account, he approached out-going NASA Administrator James Fletcher, who stepped down on May 1, 1977, and received a few thousand dollars to conduct his study. During the mid-to-late 1970s, however, NASA sought to avoid becoming associated with plans for manned missions beyond low-Earth orbit. Agency managers feared that such plans would antagonize Congress and the White House - not to mention the American public - and interfere with its efforts to secure funding to build the Space Shuttle. NASA declined to publish Singer's final report, but he found a receptive audience for his mission concept at the first Case for Mars conference in 1981.

Singer's $10-billion expedition to outer martian moon Deimos (images above) would see six to eight astronauts telerobotically operate 10-to-20 Mars surface rovers during a stay lasting from two-to-six months. Teleoperating rovers from a base on Deimos would be effective, Singer argued, because round-trip radio signal travel time between Deimos and Mars is only one-fifth of a second. Though no member of Singer's crew would land on Mars, a robot sample return lander would retrieve a "grab sample" from the planet's surface and two astronauts would land on Phobos in a small "vehicle/laboratory."

Two members of the crew would be "medical scientists" who would gather data on human reactions to weightlessness, radiation, and isolation. The PH-D expedition would thus provide important new data on long-duration spaceflight that would enable ambitious follow-on voyages, including Mars landing missions.

The PH-D spacecraft would have a mass of about 300 tons at departure from Earth orbit, making it a lightweight among proposed Mars expedition spacecraft. It would comprise three main parts. The first, the manned habitat, would contain crew living quarters, a galley, water processing and waste management equipment, a recreation/conference area, and the spacecraft's command/control station. The second part, the experimental section, would include a laboratory, 10-to-20 teleoperated major rovers, "a large number" of hard-landing penetrators, "several" Mars orbiters, and the manned Phobos vehicle/laboratory. The third part, the propulsion section, would include solar-electric and chemical propulsion systems.

Singer proposed a launch from Earth orbit in 1990-1991 to take advantage of a Venus flyby gravity-assist opportunity that would increase the spacecraft's speed without using propellants. At the PH-D expedition's start, the unpiloted solar-electric propulsion system would activate and begin to spiral out from Earth as it slowly gained speed.

The solar-electric system would use electricity generated by a large solar array to ionize and expel argon gas, yielding steady low thrust over long periods with minimal use of propellant. Solar-electric propulsion would also reduce the quantity of chemical propellants needed to accomplish the mission and the Earth-Mars transfer time and, because it could thrust as needed during Earth-Mars transfer, providing Earth-departure date flexibility. A few weeks after thruster start, as the solar-electric propulsion system was about to escape Earth, the astronauts in the habitat and experimental section would use chemical propulsion to quickly catch up with it and dock.

Prior to Deimos departure, the astronauts would cast off the experimental section. When the PH-D spacecraft reached high-Earth orbit, the habitat would separate from the solar-electric system and use its chemical propulsion system to descend rapidly to low-Earth orbit for rendezvous with a Space Shuttle orbiter. The PH-D expedition would, Singer estimated, last "something less than two years."

"The PH-D Proposal: A Manned Mission to Phobos and Deimos," AAS 81-231, S. Fred Singer, The Case for Mars, Penelope Boston, editor, 1984, pp. 39-65; paper presented at the Case For Mars conference, Boulder, Colorado, April 29-May 2, 1981.

Mission to II P 6-1 (1968)

2012-01-13T22:41:00.000-08:00

The automated Lunar Orbiter II spacecraft (bottom image above) lifted off from Launch Complex 13 at Cape Kennedy, Florida, on November 6, 1966. The 385.6-kilogram spacecraft arrived in equatorial lunar orbit on November 10 and began its mission to image 13 primary and 17 secondary candidate Apollo landing sites. All were located near the lunar equator.

One of the sites on Lunar Orbiter II's primary list was designated II P-6. Located in southwest Mare Tranquillitatis north of the crater Moltke, the rectangular area had already received attention from a NASA spacecraft; Ranger 8 snapped 7137 images of the region as it fell toward destructive impact on February 20, 1965. Though pocked with smallish craters, some containing large boulders, the gray basaltic plain had virtually no slope and was relatively free of the ridges, rilles (sinuous canyons), and domes found at other mare sites. This lack of dramatic features, though off-putting from a scientific standpoint, made II P-6 a favorite of NASA engineers anxious to ensure safe Apollo landings.

In January 1968, a little more than a year after Lunar Orbiter II successfully completed its imaging mission, A. F. H. Goetz, with Bellcomm, NASA's Washington, DC-based advance planning contractor, proposed a geologic traverse plan for an Apollo mission to a site within the II P-6 rectangle with he designated II P 6-1. His mission corresponded approximately to Lunar Landing Mission-2 (LLM-2), the second Apollo landing mission in the four-phase, 13-mission Lunar Exploration Program proposed in a January 5, 1968 Bellcomm memorandum (see link below).

Goetz assumed that LLM-2 would include two 2.5-hour moonwalks, and that one moonwalk would be taken up with deploying the Apollo Lunar Scientific Experiment Package (ALSEP) on the lunar surface. He also assumed that the Apollo Lunar Module (LM) dispatched to II P 6-1 might land anywhere within an ellipse about eight kilometers long by five kilometers wide, and that the astronauts would need to remain within one kilometer of their spacecraft.

The wide margin of error and small area of exploration meant that detailed pre-mission traverse planning would be impossible. Goetz proposed that the astronauts use their LM's top-mounted docking port as an observation platform for planning their own geologic traverse after they landed on the moon. An astronaut would open the port, seven meters above Mare Tranquillitatis, and stand on the LM's ascent stage engine cover to look out over the landscape.

Goetz chose at random two landing points within the II P 6-1 ellipse and planned traverses for them based on Lunar Orbiter II images. The first, traverse A, would include four stations when the astronauts set out from their LM. Of particular note was station 4, a 25-meter crater with a bright ejecta blanket where the astronauts would attempt to determine the depth of the bright material. Also of note was traverse A station 5, a north-south-trending chain of small craters, which Goetz assumed would be added after the astronauts noticed it while exploring station 4. This illustrated that the traverse could be modified as needed. The astronauts would investigate the station 5 crater chain to determine if it was of volcanic or impact origin, then would return to their LM.

The second hypothetical traverse, traverse B, assumed an LM landing 1.9 kilometers south of the traverse A LM site. Of particular note were station 3, a 35-meter crater on the rim of a "ghost crater" (that is, one mostly buried by mare lavas), which Goetz believed would provide the astronauts with an opportunity to sample bedrock, and station 6, a 180-meter ghost crater containing two boulders large enough to show up in Lunar Orbiter II images. Goetz suggested that the boulders would create permanently shaded places that might shelter ice.

The astronauts would walk a total of 2.31 kilometers during traverse A. Goetz estimated that they would spend 50 minutes walking and one hour and 40 minutes exploring the five stations. Traverse B would see the astronauts walk 2.44 kilometers in 55 minutes and spend one hour and 35 minutes at seven stations. Based on analysis of his two hypothetical traverses, he estimated that the astronauts would be able to reach at least 80% of the interesting features within a kilometer of their LM after a landing anywhere within the II P 6-1 ellipse.

An ellipse within II P-6 very close to Goetz's II P 6-1 ellipse was designated Apollo Landing Site (ALS) 2. In May 1969, the crew of the Apollo 10 mission imaged the site from lunar orbit by (top image above). On July 20, 1969, it became the target landing site of Apollo 11, the first piloted lunar landing mission. After dodging 185-meter-wide West crater (top image below), astronauts Neil Armstrong and Edwin "Buzz" Aldrin flew over Little West and landed the LM Eagle just short of Double crater. The touchdown point was located just beyond the western end of the AlS 2 ellipse. A few hours later, the astronauts stepped outside for a little more than two hours. They limited most of their activities to a 30-meter-wide area centered on Eagle (bottom image below). Toward the end of their brief single moonwalk, Armstrong made a rapid foray to the Little West crater rim, roughly 60 meters from the LM.

On only one mission did an astronaut poke his helmeted head out through the LM docking port on the moon; on Apollo 15 in July-August 1971, David Scott used the LM Falcon's top-mounted port to get his bearings at the Hadley-Apennine landing site ahead of three traverses planned before the mission left Earth. This followed the Apollo 14 mission (January-February 1971), which saw Alan Shepard and Ed Mitchell become lost amid hummocky terrain surrounding Cone crater at the Fra Mauro landing site.

A Proposed Plan for Geologic Exploration on the Second Apollo Landing Mission - Case 710, A. F. H. Goetz, Bellcomm, January 31, 1968.

http://beyondapollo.blogspot.com/2010/01/four-phase-apollo-1968.html

25-kilowatt Power Module (1977-1981)

2012-01-07T01:19:00.000-08:00

According to historians Andrew Dunar and Stephen Waring, writing in their 1999 book Power to Explore: A History of Marshall Space Flight Center, in the 1970s two lines of thought emerged within NASA concerning manned spaceflight's course after the Space Shuttle became operational. On the one hand, there was the "revolutionary" line taken by Johnson Space Center (JSC) in Houston, Texas. On the other was the "evolutionary" line of NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama.

At JSC, many managers assumed that, as soon as the Shuttle became operational, NASA would get a green light to assemble a large, new-design, multipurpose space station in low-Earth orbit (LEO). They envisioned that a future President would make a speech much like President John F. Kennedy's May 25, 1961 "moon speech." Visionary goal thus proclaimed, the funding floodgates would open.

At MSFC, by contrast, many managers expected that NASA budgets would remain tight for the foreseeable future, so any space technology development that took place would need to be incremental; that is, it would have to begin with existing space hardware and occur in small steps. MSFC's work on Skylab, a temporary LEO space station launched in May 1973 on the last Saturn V rocket to fly, probably helped to shape their outlook. The 169,950-pound Skylab "cluster," which comprised the Multiple Docking Adapter, the Apollo Telescope Mount (ATM), and the Orbital Workshop, had been conceived originally as an element of the Apollo Applications Program (AAP). As its name implies, AAP was meant to apply hardware developed for the Apollo lunar program to new tasks.

When MSFC engineers looked at the Space Transportation System (STS), as NASA called the Space Shuttle and its stable of expendable upper stages and European-built Spacelab components, they saw not the promise of a big new space station, but rather a system which, once operational, could benefit from evolutionary development. In particular, they noted that Spacelab, which MSFC was assigned to integrate with the Shuttle, could not reach its potential as an orbiting laboratory while the Shuttle Orbiter's planned maximum time in space was only seven days. The Orbiter and its payloads would rely for electricity on the former's fuel cells, which meant that the quantity of fuel-cell reactants the Orbiter could carry would determine their endurance.

In early 1977, with the first STS flight test officially planned for March 1979, MSFC proposed "the first step beyond the baseline STS" - a Power Module (PM) capable of supplying 25 kilowatts of electricity continuously. The solar-powered PM was meant to be deployed into LEO from a Shuttle Orbiter payload bay and left in space for up to five years. A succession of Orbiters bearing Spacelab modules and pallets in their payload bays would dock with the PM and use its electricity to remain in orbit for up to 30 days at a stretch (top image above).

Alternately, a Shuttle Orbiter could attach a "freeflyer" payload to the orbiting PM and leave it to operate on its own. This appealed to materials scientists, who worried that astronauts' movements on board the Shuttle Orbiter and Spacelab would rattle and ruin their microgravity experiments. Orbiters would periodically dock with the materials science freeflyer/PM combination to remove experiment products - for example, large flawless crystals - and to replenish raw materials.

In addition to electricity, the PM "building block" would provide thermal and attitude control. The latter would permit a docked Orbiter to conserve its Reaction Control System propellants. Freeflyer payloads meant to be docked with the PM could be built without thermal and attitude control systems, reducing their cost.

MSFC engineers planned at first to base the PM on the Skylab ATM design (middle image above). They quickly found, however, that modifying the ATM to meet stringent Orbiter payload bay safety requirements would cost more than a new design. They retained the ATM's octagonal cross-section, however, because they found that it made efficient use of the Orbiter's cylindrical payload bay volume while providing flat surfaces upon which to mount subsystems.

Although it nixed the ATM, MSFC still aimed to lower the PM's cost by using subsystems developed for Skylab, Spacelab, Shuttle, and other programs. These included three Skylab Control Moment Gyros for attitude control and four curved Shuttle payload bay door radiators for thermal control. MSFC planned to update and improve Skylab systems used in the PM based on Skylab flight experience. All major PM subsystems would be redesigned for easy replacement by spacewalking astronauts.

The 31,000-pound PM would measure 55 feet long from the framework holding its aft- and side-facing international docking ports to the forward ends of its stowed twin solar arrays. The PM would fill most of the Shuttle Orbiter's 15-by-60-foot payload bay, leaving room only for a docking tunnel with an international docking port at the front of the bay, attached to the aft wall of the Orbiter crew compartment.

Upon arrival in LEO, the astronauts would open the Shuttle Orbiter's payload bay doors and release the five pins that secured the PM in the bay. They would then use the Orbiter's robot arm to lift the PM from the bay and berth its side-facing docking port on the Orbiter port. This would position the module so that it extended out over the crew compartment.

The astronauts would next extend the PM's twin solar arrays. Fully extended, each wing-like array would measure 131 feet long by 30 feet wide. They would together span a little more than 276 feet. MSFC sized the arrays to generate a total of 59 kilowatts of electricity; that is, 34 kilowatts more than the PM would supply to Spacelab-carrying Orbiters and freeflyers. A portion of this excess would power PM systems, but the majority would charge batteries in the PM so that it could supply a constant 25 kilowatts throughout its roughly 90-minute orbital day-night cycle.

MSFC acknowledged that the big solar arrays would degrade over time; its engineers estimated that over five years they would lose 5% of their generating capacity. Similarly, the PM's batteries would gradually lose their ability to charge and discharge. After five years, a Shuttle Orbiter might be sent up to recover the PM and return it to Earth for refurbishment. Another Orbiter would then launch it back to LEO to continue its duties.

MSFC engineers presented the PM concept to scientists at an MSFC-sponsored solar-terrestrial physics workshop in October 1977. They found broad support for the new capabilities the PM would give to the baseline STS.

They also proposed that the PM become part of plans to reuse Skylab. MSFC contractor McDonnell Douglas had "interrogated" the abandoned space station's data handling system and found that, nearly four years after its last crew had returned to Earth, reactivation remained feasible. The first step toward Skylab reuse would be for a Space Shuttle to rendezvous with it late in 1979 and boost it to a longer-lived orbit.

The PM would be a late addition to the revitalized Skylab cluster; MSFC did not expect that the new STS element would reach LEO for the first time until 1983, by which time several Shuttle Orbiters would already have visited Skylab. Once added to Skylab, however, the PM would enable it to support as many as six astronauts without a Shuttle Orbiter present. They would perform experiments with large-scale space construction and early space industrialization.

MSFC engineers hoped that the PM would also contribute toward NASA's quest for Skylab's successor. They envisioned that PMs attached to Shuttle Orbiters, freeflyers, and Skylab might lead to PMs attached to Spacelab-derived habitat and laboratory modules during the 1980s.

In 1978, the Huntsville center contracted with Lockheed Missiles & Space Company to study PM evolution. MSFC expected that PM development might lead to simultaneous operation of several small specialized "space platforms," each with at least one PM attached. The platforms would not need to be staffed continuously. MSFC argued that several small platforms would best serve scientific and engineering disciplines with conflicting needs, and might cost less than a single large station besides.

In early 1979, NASA Headquarters authorized MSFC to spend $90 million on PM hardware development. The Huntsville center created a PM Project Office in March 1979. At about the same time, however, the space agency abandoned plans to reuse Skylab because the Space Shuttle would not be ready in time to prevent its uncontrolled reentry. Skylab reentered Earth's atmosphere over Australia on July 11, 1979.

JSC, meanwhile, pitched a new-design Space Operations Center (SOC). The space station would include hangars for reusable auxiliary spacecraft and satellite repair, robot arms, habitat and laboratory modules, and truss-mounted solar arrays spanning more than 400 feet.

STS-1, the maiden flight of Columbia, the first Space Shuttle Orbiter, took place in April 1981. James Beggs, President Ronald Reagan's choice for NASA Administrator, was confirmed two months later. Beggs soon sought presidential approval for a space station. This move seemed to favor JSC's revolutionary vision. At the same time, however, Beggs informed MSFC that he wanted to buy the new station "by the yard" - that is, as money became available. This approach seemed more in line with MSFC thinking.

In November 1981, NASA Headquarters halted PM, SOC, and other station-related work at MSFC and JSC. According to Dunar and Waring, it did this to take charge of station development and to end MSFC-JSC rivalry. Following Reagan's January 1984 State of the Union Address, in which he called upon NASA to build a space station by 1994, JSC's revolutionary vision seemed to win out. JSC was designated "lead center" for space station in early February 1984.

Although Reagan authorized NASA to spend only the $8 billion Beggs had told him the station would cost and had specifically called for a space laboratory in his State of the Union Address, the agency's first baseline station design, the "Dual Keel," was an elaborate combination of lab, Earth/space observatory, and shipyard measuring more than 500 feet wide (bottom image above). Like the SOC, the Dual Keel included hangars, robotics, and a small fleet of reusable auxiliary vehicles.

The Dual Keel's complex multipurpose design immediately came in for criticism. Scientists, for example, complained that space construction and the comings and goings of auxiliary spacecraft were bound to spoil the station's microgravity environment. Congress, meanwhile, accused NASA of low-balling its cost estimate to gain the project's approval.

Congressional cost containment, combined with the Challenger accident, concern over the number of assembly and maintenance spacewalks the station would need, and a rapidly expanding U.S.-Russian space partnership (one which would have been unthinkable when Reagan delivered his January 1984 speech), led to a decade-long series of station redesigns. The station shrank and lost many of its proposed capabilities. This untidy evolution yielded the International Space Station (ISS), a U.S.-Russian hybrid with Japanese and European labs and Canadian robotics.

Ironically, the first ISS element launched into space amounted to a PM. The Russian-built, U.S.-funded FGB (top image below) provided the second ISS element to reach space, U.S. Node 1, with electricity and attitude control from December 1998 to July 2000, when they were joined by what amounted to a habitat module - the Russian Service Module (bottom image below). At that point, ISS became capable of supporting long-duration crews.

Guntersville Workshop on Solar-Terrestrial Studies, NASA Conference Publication 2037, "summary papers from a University of Alabama in Huntsville/NASA Workshop conducted October 13-17, 1977, at Lake Guntersville State Park Convention Center, Guntersville, Alabama," NASA George C. Marshall Space Flight Center, 1978.

"The 25 kW Power Module - First step beyond the baseline STS," G, Mordan; paper presented at the American Institute of Aeronautics and Astronautics Conference on Large Space Platforms: Future Needs and Capabilities held in Los Angeles, California, September 27-29, 1978.

25 kW Power Module Updated Baseline System, NASA TM-78212, NASA George C. Marshall Space Flight Center, Alabama, December 1978.

Evolution of Earth-moon transportation (1962)

2012-01-06T12:29:00.000-08:00

When Wernher von Braun turned 50 on March 23, 1962, he was director of Marshall Space Flight Center (MSFC), NASA's lead facility for rocket development. The German rocketeer could look back on a momentous career that included the development and operational deployment of the first large liquid-propellant missile (the V-2/A-4, first launched in 1942) and the launch of the first U.S. Earth satellite (Explorer 1, January 31, 1958). Following President John F. Kennedy's May 1961 "Moon Speech," Von Braun could look forward to launching lunar expeditions using his giant Saturn and Nova rockets.

In a paper published in a special volume commemorating Von Braun's half-century mark, MSFC Future Projects Office director Heinz Koelle looked beyond Apollo to predict the course and cost of Earth-moon transportation through 1980. Koelle, a Luftwaffe pilot in the Second World War, had left Germany in 1955 to join Von Braun in the United States. He had led the U.S. Army's Project Horizon lunar fort study in 1959, and had transferred to NASA with Von Braun and the rest of the U.S. Army space apparatus in 1960.

For his cost analysis, Koelle considered seven methods of transporting cargo and crew from the Earth to the moon. They constituted together an evolutionary progression of lunar transportation modes offering rapidly increasing capability and efficiency.

Koelle's starting point was the Earth-Orbital Rendezvous (EOR) mode, which would see an expendable two-stage chemical rocket designated Nova Jr. I launch into Earth orbit a liquid hydrogen/liquid oxygen Earth-orbit departure stage. The Earth-orbit departure stage was approximately equivalent to the Apollo Saturn V S-IVB third stage. Koelle's Nova Jr. I rocket would include five 1.5-million-pound-thrust engines in its first stage and four 200,000-pound-thrust engines in its second. It was, thus, roughly equivalent to the first two stages of what eventually flew as the Apollo Saturn V rocket.

A second Nova Jr. I would launch a two-stage lunar lander. Earth-orbit departure stage and lander would dock in Earth orbit, then the former would fire its single 200,000-pound-thrust engine to place the latter on course for the moon. After completing their lunar surface mission, the astronauts would lift off in the lander's upper stage, fly back to Earth, and enter Earth's atmosphere directly.

Flight tests for the EOR mode would begin at the start of 1965, with operational flights spanning from mid-1967 to mid-1968. Koelle wrote that EOR mode was "very close to the mission profile which will probably be employed for the first Apollo flight." (In fact, NASA opted for the faster, cheaper, but less evolutionarily open-ended Lunar Orbit Rendezvous mode for Apollo in July 1962, four months after Koelle presented his paper.)

Koelle's second mode, dubbed "Direct," would include a lander upper stage identical to that in Mode 1, except that it would use "high-energy" chemical propellants to reduce total lander mass by one-third. This would eliminate the requirement to separately launch the two-stage lunar lander and Earth-orbit-departure stage, enabling a single Nova Jr. I rocket to launch each moon trip. Mode 2 flight tests would start early in 1965, with operational lunar flights spanning from early 1967 to mid-1969.

Step three in Koelle's evolutionary progression would be identical to Mode 2, except that the Earth-orbit departure stage would contain a nuclear reactor that would heat and expel liquid hydrogen propellant. In addition, a single-stage lunar lander burning high-performance chemical propellants would replace Mode 1's two-stage lander. Flight tests for Mode 3 would begin in mid-1967, and operational flights would span from mid-1969 to the end of 1972.

Koelle designated Mode 4 "EOR mode - reusable Earth-launch rocket." It would combine a reusable Nova Jr. II rocket with a nuclear Earth-orbit departure stage. The Nova Jr. II would have the same thrust capability as the Nova Jr. I, but would include recovery systems - presumably parachutes and flotation devices, though Koelle did not specify - which would cut costs but would also reduce the mass it could place into Earth orbit. Because of the reduction in capability, two Nova Jr. II's and one rendezvous in Earth orbit would be required for each lunar expedition (which, presumably, would raise costs). Flight testing for Mode 4 would start in early 1969, and operational flights would begin in early 1971.

Koelle wrote that his Mode 5, which he designated "Lunar-Orbit Refueling mode," might serve an "early" lunar base (that is, one unable to supply rocket propellants to visiting spaceships). A reusable nuclear ferry spacecraft would provide cargo and crew transport between Earth orbit and lunar orbit and would refuel in Earth orbit between flights. Return to Earth orbit would eliminate the "hazardous" direct Earth atmosphere reentry of earlier modes, he added. A reusable single-stage lunar lander would provide transport from the ferry in lunar orbit to the lunar surface. The lander would refuel in lunar orbit from the ferry's tanks. Flight testing of this mode would start at the beginning of 1970, and operational flights would span 1972-1976.

Lunar-Surface Refueling mode, similar to Mode 5, would be "of interest only if it [became] possible to produce propellants on the Moon." Availability of lunar propellants would mean that the nuclear-propelled ferry would not have to carry lander propellants, enabling it to transport more cargo between Earth orbit and lunar orbit. The lunar lander would double in size to carry the extra cargo, so would need a more powerful rocket engine. Flight testing for Mode 6 would begin early in 1973, with operational flights spanning 1975-1978.

Koelle called the seventh and last mode in his evolutionary program "Direct mode - reusable nuclear spaceship." He explained that it offered "first-class transportation," but devoted relatively little attention to it in his paper because it would "require the production of huge amounts of liquid hydrogen on the Moon, which at this time does not appear feasible." A reusable Earth-launch vehicle - a Nova Jr. II variant with a reduced chemical propellant load - would place into Earth orbit a reusable nuclear spaceship with only enough propellant for a one-way Earth-moon trip. The nuclear spaceship would then fly to the moon, land, and refuel for the moon-Earth trip.

Lunar surface mission accomplished, the nuclear spaceship would lift off from the moon and fly back to Earth. Nearing Earth, it would fire its engine to limit the deceleration the crew would feel during atmosphere reentry to about 1.5 times the pull of gravity on Earth's surface. The nuclear spaceship would then either deploy a fabric "flex wing" at a height of 10 kilometers and glide to a landing, or would land under nuclear rocket power. It would then be refurbished for reuse. Flight testing for this mode would begin in early 1977, and operational flights would begin in 1979.

Koelle placed the cost of a Mode 1 trip to the moon and back at $40 million per astronaut, and recommended that a more economical mode replace it as soon as possible. Mode 2 would cut the cost per astronaut in half, and Mode 3 would halve it again. He called Mode 3's cost "the best that can be expected with expendable systems." Mode 5, with its reusable nuclear ferry, would see the cost per astronaut slashed to $2 million, while in Mode 6 it would fall to about $700,000. The cost per pound delivered to the lunar surface would fall rapidly from $1600 in 1967 to $300 in 1976.

Koelle then detailed a highly ambitious traffic model for lunar exploration and development. The year 1967 would see six Mode 1 missions deliver 342,000 pounds of cargo to the lunar surface for $790 million. Traffic, amount of cargo delivered, and total cost would plateau for several years in the early 1970s despite the introduction of reusable systems, with 19 Mode 3 missions delivering 674,000 pounds of cargo to the moon for a total cost of $875 million in 1970, and 22 Mode 5 missions delivering 778,000 pounds for $937 million in 1972. Lunar traffic would peak in 1978, 11 years after the first Mode 1 mission, when 112 Mode 6 missions would deliver 13,380,000 pounds of cargo to the moon's surface for only $1.155 billion.

"Evolution of Earth-Lunar Transportation Systems," Heinz H. Koelle, From Peenemunde to Outer Space, "a Volume of Papers Commemorating the Fiftieth Birthday of Wernher von Braun," NASA Marshall Space Flight Center Technical Report, 1962, pp. 121-137.

Mars multi-rover mission (1977)

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Planetary scientist Bruce Murray (middle image above) became director of the Jet Propulsion Laboratory (JPL) in April 1976, just three months before Viking 1 was due to land on the northern plains of Mars. Though NASA's Langley Research Center managed Project Viking, JPL included Viking Mission Control. When Viking 1 landed, JPL could expect to play host to hundreds of journalists from all around the Earth.

According to his 1989 memoir Journey into Space: The First Thirty Years of Space Exploration, Murray saw this as an opportunity. He quickly assembled a group of six engineers to propose planetary missions that he could pitch to the journalists and, through them, to U.S. taxpayers. The missions, which he dubbed "Purple Pigeons," were intended to include both "high science content" and "excitement and drama [that would] garner public support." By August 1976, the Purple Pigeons flock included a solar sail mission to Halley's Comet, Mars Surface Sample Return (MSSR), a Venus radar mapper, a Saturn/Titan orbiter/lander, a Ganymede lander, an asteroid tour, and an automated lunar base.

The Purple Pigeons effort continued even after Viking 2 landed (September 1976) and the journalists went home. In a February 1977 JPL report, for example, JPL engineers described a Purple Pigeon mission that would explore Mars with up to four rovers simultaneously. The Viking-based multi-rover mission would include a pair of identical 4800-kilogram spacecraft, each consisting of a Viking-type orbiter and a 1578-kilogram Mars lander bearing twin 222.4-kilogram rovers. The rovers would, the report stated, perform traverses of up to 1000 kilometers to "regions difficult to reach by direct landings." This would, it added, fill the gap between "detailed information" from MSSR missions and "global information" from Mars orbiters.

Most MSSR plans of the 1970s assumed a "grab" sample; that is, that the stationary MSSR lander would return to Earth a sample of whatever rocks and soil happened to be within reach of its robotic sample scoop. The report suggested that the rovers of the multi-rover mission might enhance a follow-on MSSR mission by collecting and storing samples as they roved across the planet. After the MSSR lander arrived on Mars, the rovers would rendezvous with it and hand over their samples for return to Earth. The report contended that its multi-rover/MSSR strategy would be "an enormous advance over even multiple grab samples" collected by MSSR landers at widely scattered sites.

At the time the Purple Pigeons team proposed the multi-rover mission, NASA intended to launch all payloads, including interplanetary spacecraft, on board reusable Space Shuttles. The Shuttle orbiter would be able to climb no higher than about 500 kilometers, so launching payloads to higher Earth orbits or interplanetary destinations would demand an upper stage. The powerful liquid-propellant Centaur upper stage would not be ready in time for the opening of the Mars multi-rover launch window, which spanned from December 11, 1983 to January 20, 1984, so JPL tapped a three-stage solid-propellant Interim Upper Stage (IUS) to push its Purple Pigeon out of Earth orbit toward Mars.

After an Earth-Mars cruise lasting about nine months, the twin multi-rover spacecraft would arrive at Mars a week or two apart between September 16 and October 27, 1984. They would each fire their main engines to slow down so that Mars's gravity could capture them into an elliptical orbit with a periapsis (low point) of 500 kilometers, a five-day period, and an inclination of 35° relative to the martian equator.

The multi-rover landers would then separate and each fire a solid-propellant de-orbit rocket at the apoapsis (high point) of its orbit to begin descent to Mars's surface. Landing sites between 50° north latitude and the south pole would in theory be accessible, though the need for a direct Earth-to-rover radio link would in practice prevent landings below 55° south.

The landers would each be encased within an aeroshell with a heatshield for protection during the fiery descent through the martian atmosphere. The aeroshell would have the same 3.5-meter diameter as its Viking predecessor, though its afterbody would be modified to make room for the large cooling vanes of the twin rovers' electricity-producing Radioisotope Thermal Generators (RTGs).

After the landers touched down, the orbiters would maneuver to areosynchronous orbit. In such an orbit, 17,058 kilometers above Mars's equator, only minor orbital corrections will enable a spacecraft to "hover" indefinitely over one spot on the equator. Each orbiter would position itself over a spot on the equator near its lander's longitude so that it could relay radio signals between its rovers on Mars and operators on Earth.

The multi-rover lander, which would serve no purpose beyond rover delivery, would constitute a radical departure from the Viking lander design, though it would use Viking technology where possible to save development costs. It would comprise a rectangular frame to which would be attached three uprated Viking-type terminal descent engines, two spherical propellant tanks, and three beefed-up Viking-type landing legs.

The 1.5-meter-long rovers would be mounted on the lander frame with their four 0.5-meter-diameter wire wheels compressed. Releasing a latching mechanism would permit the wheels to expand, raising the rover off four stabilizing "taper pins." The pins and one terminal descent engine would then swing out of the way, ramps would deploy, and the first rover would roll onto Mars's rocky surface. The second rover would then ride a motor-driven "dolly" to the first rover's initial position before unlatching and joining its twin on the ground.

The rovers would each deploy a one-meter-tall boom holding a still-image camera, a floodlight, a strobe light, a weather station, and a pointable horn-shaped radio antenna. The camera/antenna boom, the tallest part of the rover, would stand about two meters above the surface. Controllers on Earth would then put the rovers through an initial checkout lasting at least two weeks. The checkout would culminate in slow "manual" (Earth-controlled) and faster "semiautonomous" (Earth-directed but rover-controlled) traverses.

In semiautonomous mode, operators would plan traverse routes and science targets using stereo images from the rover camera taken from terrain "high points," then would command the rover to proceed. The rovers might assist each other in traverse planning; for example, "high point" pictures from one might fill in blind spots in the other's field of view. "After the first few kilometers of traverse," the JPL engineers assumed, operators on Earth would "begin to build an intuitive feeling for the Martian geography and its impact on the rover capabilities, allowing them to plan better paths." The rovers would also photograph each other to enhance the mission's "general public appeal."

The rover mobility system would include one electric drive motor per wheel, eight proximity sensors for obstacle detection, inclinometers to monitor rover tilt, motor temperature sensors to judge wheel traction, a gyrocompass/odometer, a laser rangefinder with a 30-meter range, and an "8-bit word, 16k active, 64k bulk, floating point arithmetic and 16-bit accuracy" computer. The JPL engineers judged that their rovers would be capable of moving at up to 50 meters per hour over terrain similar to that seen at the Viking 1 landing site (bottom image above).

Alpha-scattering X-ray fluorescence and gamma-ray spectrometers would collect data while the rovers were in motion, but all other science, including imaging and sample collection, would occur only while they were parked. Each rover would gather samples using an "articulated arm" with an "electromechanical hand."

In order to avoid "an overabundance of data from a single track," the rovers would travel slightly different routes and would rendezvous at the end of each leg of their traverse. They would, however, travel close enough together that each could aid the other in the event of trouble. If one rover became stuck in loose dirt, for example, its companion could use its articulated arm to place rocks under its wheels to improve traction. If one rover of a pair failed, the report maintained, the other would continue to yield "good, solid science."

The rovers would be designed to operate for at least one martian year (about two Earth years) to help ensure that at least one of the four could rendezvous with the follow-on MSSR mission, which would leave Earth in 1986. The JPL engineers concluded their report by calling for new technology development to ensure that adequate power and mobility systems would become available by the time their Purple Pigeon was due to fly.

Feasibility of a Mars Multi-Rover Mission, JPL 760-160, Jet Propulsion Laboratory, February 28, 1977.

Project Icarus (1967)

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Walter Baade used the 48-inch telescope at Palomar Observatory to capture humankind's first image of asteroid 1566 Icarus on June 26, 1949. Icarus, it was soon found, is unusual because its elliptical orbit takes it from the inner edge of the Main Asteroid Belt beyond Mars's orbit to well within Mercury's orbit. Every 19 years Icarus and Earth pass within five million miles of each other at a relative velocity of about 18 miles per second. Baade detected Icarus during one of these close encounters.

MIT Professor Paul Sandorff taught the Interdepartmental Student Project in Systems Engineering in the Spring 1967 Term at Massachusetts Institute of Technology (MIT) in Boston. He noted that Icarus and Earth would pass each other at a distance of four million miles on June 19, 1968. He then asked his students to suppose that, instead of missing Earth on that date, Icarus would strike in the Atlantic Ocean east of Bermuda with the explosive force of 500,000 megatons of TNT. Debris flung into the atmosphere would cool the planet and a 100-foot wave would inundate MIT. Sandorff gave his class until May 27, 1967 to develop a plan for averting the catastrophe.

In 1967, the physical characteristics of Icarus were little known. For purposes of their study, Sandorff's students assumed that it measured 4200 feet in diameter and had a density of 3.5 grams per centimeter, yielding a mass of 4.4 billion tons. They acknowledged, however, that Icarus might be a defunct comet nucleus, in which case its density and mass would likely be considerably less.

In March 1967, the MIT students visited Cape Kennedy, Florida, to size up U.S. space capabilities. At the time, the first manned flight of the Apollo Command and Service Module (CSM) (bottom image above) had been postponed indefinitely following the January 27, 1967 Apollo 1 Fire and the Saturn V moon rocket (middle image above) had yet to fly. (Apollo 4, the successful first Saturn V test flight, would occur on November 9, 1967.) Nevertheless, the students wrote that "the awesome reality" of the Vertical Assembly Building (VAB), in which the Saturn V and Apollo would be prepared, and the twin Complex 39 pads, from which they would be launched, had "completely erased" any doubts they might have had about using Apollo/Saturn technology in their project.

Sandorff's students proposed to hijack Project Apollo, delaying NASA's first lunar landing by about three years. They would take over the first nine Saturn V rockets earmarked for the moon program, commence construction in April 1967 of a third Complex 39 launch pad, and add a high bay to the VAB, bringing the total to four. Three Saturn Vs would be used for flight tests, and the remainder would each launch toward Icarus one heavily modified unmanned Apollo CSM bearing a 44,000-pound nuclear bomb with a destructive yield of 100 megatons.

The Icarus CSM - which the MIT students dubbed the Interceptor - would comprise three modules: a drum-shaped propulsion module corresponding to the Apollo Service Module (SM), with attitude control thrusters and a Service Propulsion System (SPS) main engine; a drum-shaped payload module based on the SM structural design bearing the nuclear device; and a stripped-down Command Module (CM) containing Icarus detection sensors and an MIT-designed Apollo Guidance Computer. Unlike the two-module Apollo CSM, the three modules of the Interceptor would remain bolted together throughout its flight.

The first Project Icarus Saturn V (Saturn-Icarus 1) would leave Cape Kennedy on April 7, 1968, 73 days before the asteroid was due to collide with Earth. Its payload, Interceptor 1, would reach Icarus 60 days later, when Icarus was 20 million miles from Earth. At about the time Interceptor 1 was due to reach its target, the MIT Lincoln Laboratory's Haystack radar would detect Icarus for the first time.

Saturn-Icarus 2 would launch on April 22, 1968, 58 days before Icarus was due to strike. Interceptor 2 would reach its target 15.5 million miles and 10 days out from Earth. Saturn-Icarus 3 would lift off on May 6, 1968, 44 days before Icarus was due to arrive, and its Interceptor would reach Icarus when it was one week and 11 million miles out from Earth. Saturn-Icarus 4 would lift off on May 17, 1968, 33 days before Icarus arrival, and Interceptor 4 would reach the asteroid 28 days later, when Earth and Icarus were 7.7 million miles apart.

Saturn-Icarus 5 would leave Earth near dawn on the U.S. east coast on June 14, 1968, and Interceptor 5 would reach Icarus 1.4 million miles out from Earth, 22 hours before expected impact. By then, the asteroid would appear as a modest star in the pre-dawn sky near the constellation Orion. Saturn-Icarus 6 would lift off a few hours after Saturn-Icarus 5. Icarus would be about 20 hours and 1.25 million miles from impact when Interceptor 6 reached it.

As each Interceptor closed to within a quarter-million miles of Icarus, an optical sensor in its nose would spot the asteroid. Based on its data, the SPS and thrusters would adjust its course to ensure a successful interception.

As the Interceptor closed to a distance of 550 feet, a radar would detect Icarus and trigger the nuclear device, which would explode at a distance of from 50 to 100 feet. If the students' assumptions about Icarus's mass and density were correct, then each 100-megaton near-surface nuclear blast would excavate a bowl-shaped crater up to 1000 feet wide. The effect the explosions would have on Icarus's course was, of course, not known with precision; the students calculated that each blast would alter its velocity by between eight and 290 meters per second.

The MIT students acknowledged that an explosion might shatter Icarus; in that event, subsequent Interceptors would target the largest fragments. Data from each Interceptor as it approached Icarus and from Earth-based optical telescopes and radars would be used to target subsequent Interceptors as needed. Conversely, if fewer than six explosions were sufficient to deflect or destroy the asteroid, then the remaining Saturn V rockets and Interceptors would stand down.

All but one of the Interceptors would be joined at Icarus by a separately launched 540-pound Intercept Monitoring Satellite (IMS) based on the Mariner II design. Mariner II, the first successful interplanetary probe, had flown past Venus on December 14, 1962 (image below). In addition to data immediately useful for Project Icarus, the IMS would provide pure science data.

The first IMS would leave Earth atop an Atlas-Agena rocket on February 27, 1968. It would pass between 70 and 135 miles of Icarus at the time of the first explosion. This would place it outside of the zone of large high-velocity debris from the explosion, but within the zone of plasma, dust, and small debris so that it could gather data on Icarus's composition. A 50-pound foam-honeycomb bumper would shield the IMS during passage through the debris cloud.

No IMS would monitor the fifth interception (if it occurred) unless the sixth interception were called off. The IMS for monitoring the sixth (or fifth) interception would lift off on June 6, 1968, between the Saturn-Icarus 4 and 5 launches.

Professor Sandorff's class estimated that Project Icarus would cost $7.5 billion. It would, they calculated, stand a 1.5% chance of only fragmenting the asteroid. If this happened, then Icarus might cause even more damage to Earth than if it had been permitted to impact intact. The probability that the damage Icarus would cause would be reduced by their project's efforts was, however, 86%, and the probability that Project Icarus would succeed in preventing any part of the asteroid from reaching Earth was 71%.

Project Icarus, MIT Report No. 13, Louis A. Kleiman, editor, The MIT Press, 1968.

NASA Marshall's Skylab reuse study (1977)

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On May 14, 1973, the last Saturn V to fly, designated SA-513, launched the Skylab Orbital Workshop (OWS) into a 435-kilometer-high orbit about the Earth. Flight controllers soon realized that the 100-ton space laboratory was in trouble. Although they did not know it at the time, 63 seconds after liftoff a design flaw had caused Skylab's meteoroid shield to rip away. Shield debris had jammed one of the workshop's two main electricity-producing solar arrays. The other array remained attached to Skylab's side only at its hinge (forward) end.

Shield debris had pummeled SA-513, tearing at least one hole in the tapered interstage adapter that linked its S-II second stage with the OWS. It also apparently damaged the system for separating the cylindrical adapter that linked the S-II to the S-IC first stage. The adapter, meant to separate shortly after the spent S-IC, remained stubbornly attached to the S-II all the way to orbit.

After the S-II's five J-2 engines shut down, forward-facing solid-propellant rockets ignited to push the spent stage away from Skylab. Their plumes blasted open and tore away the loose solar array. Ironically, the jammed array probably survived because it was tied down by meteoroid shield debris.

Without the protection of the reflective meteoroid shield, temperatures within Skylab's 11,303-cubic-foot pressurized volume soon soared, raising fears that its air would become tainted by outgassing from materials on board, film would be ruined, and food spoiled. Meanwhile, maneuvers designed to cool Skylab's interior tended to starve it of electricity, for they turned away from the Sun the four small solar arrays on the Apollo Telescope Mount (ATM), the beleaguered space laboratory's only functioning electricity source.

NASA immediately began a Skylab rescue effort. Engineers developed deployable sunshields and tools for freeing the stuck main array, flight controllers carefully maneuvered Skylab to maximize the amount of electricity the ATM arrays could produce while reducing temperatures on board as much as possible, and the first crew meant to board Skylab (designated Skylab 2 by NASA) hurriedly trained to become orbital repairmen.

On May 25, the Skylab 2 crew of Pete Conrad, Paul Weitz, and Joe Kerwin lifted off in an Apollo Command and Service Module (CSM) atop a Saturn IB rocket. After a failed attempt to pull open the one remaining main solar array with a hook extended from the open CSM hatch, they docked with and entered Skylab, then deployed a sunshield through an experiment airlock. Temperatures began to fall, but the Orbital Workshop remained starved for electricity. On June 7, Conrad and Kerwin succeeded in forcing open the surviving main solar array, saving not only their own 28-day mission, but also the 59-day Skylab 3 and 84-day Skylab 4 missions.

The Skylab 3 crew of Alan Bean, Jack Lousma, and Owen Garriott lifted off July 28. During their August 6 spacewalk, Lousma and Garriott deployed an improved sunshield. The Skylab 4 crew of Jerry Carr, William Pogue, and Ed Gibson boarded the laboratory on November 16. Carr and Gibson mounted a meteoroid collector on an ATM strut during their spacewalk on February 3, 1974, in the hope that a Space Shuttle crew might retrieve it as early as 1979. When the Skylab 4 crew undocked on February 8, 1974, Skylab was expected to remain aloft until 1983, when atmospheric drag would cause it to fall back to Earth. They left Skylab's airlock hatch closed but not locked so that it could provide entry for future visitors.

On June 10, 1977, former Skylab Deputy Director John Disher, NASA's Director of Advanced Programs, directed NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama, to conduct an in-house study of the feasibility of reusing Skylab in the Space Shuttle program. On November 16, 1977, MSFC engineers J. Murphy, B. Chubb, and H. Gierow presented results of the study to NASA Associate Administrator for Space Flight John Yardley. Before coming to NASA in 1974, Yardley had managed Skylab assembly at McDonnell Douglas, the Orbital Workshop's main contractor.

The MSFC engineers first assessed Skylab's condition. They reported that when the Skylab 4 crew returned to Earth, the Orbital Workshop's water system contained 1930 pounds of water (enough to supply three men for 60 days). The water, they said, probably remained potable, but could have developed a bad taste. If not still potable, it could be used for bathing. In any case, the Skylab water system included resupply points, so a Space Shuttle crew could replenish it if water transfer equipment were developed.

The oxygen/nitrogen supply remaining on Skylab was probably sufficient to supply three men for 140 days at Skylab's operating pressure of five pounds per square inch, the MSFC engineers estimated. The ventilation and carbon dioxide removal systems were almost certainly functional. Even if they were not, their most important components were designed to be replaceable in space.

The MSFC engineers also assessed Skylab's electrical power system. They estimated that the main solar array Conrad and Kerwin had freed could still generate between 1.5 and 2.5 kilowatts (KW) of electricity, and that the batteries it had charged, located in Skylab's Airlock Module, were probably still usable. The batteries for the ATM arrays, on the other hand, were almost certainly frozen. They recommended that controllers reactivate the main array electrical system from the ground before the first Shuttle visit, and that any effort to revive the ATM electrical system be left until a later time.

More problematic than the electrical system was the attitude control system, which relied on a trio of Control Moment Gyros (CMGs) to turn Skylab so that, among other things, it could point its solar arrays at the Sun. One CMG had failed and another showed signs of impending failure. In addition, Skylab's guidance computer was probably dead after being subjected to "extreme thermal cycling." The Orbital Workshop's thruster system, on the other hand, was probably operational with about 30 days of propellant remaining.

Finally, the MSFC team looked at Skylab's cooling system, which had leaked while the astronauts were on board and had probably frozen and ruptured since the last crew returned to Earth. They called "serviceability of [the] cooling system. . .the most questionable area" as far as Skylab's reusability was concerned, but added that "any inflight 'fixes' should be well within the scope of crew capability."

The MSFC engineers then proposed a four-phase plan for reactivating and reusing Skylab. The target date for the first Phase I milestone had already passed by the time they briefed Yardley: they called for an October 1977 decision on whether Skylab should be reboosted to a higher orbit, extending its orbital lifetime until about 1990, or deboosted so that it would reenter over an unpopulated area.

Assuming that NASA decided to reboost Skylab, then a ground reactivation test would occur between June 1978 and March 1979. If the reactivation test was successful, then a Space Shuttle Orbiter would rendezvous with Skylab during the Shuttle Program's fifth Orbital Flight Test mission in February 1980. The Orbiter would conduct an inspection fly-around, then deploy an unmanned Teleoperator spacecraft from its payload bay. Using a control panel on the Shuttle, the astronauts would guide the Teleoperator, which would carry an Apollo-type probe docking unit, to a docking with the front docking port on Skylab's Multiple Docking Adapter. The Teleoperator would then fire its thrusters to raise Skylab's orbit. Its work done, it would then detach, freeing up the front port for Phase II of MSFC's plan.

Phase II would begin in March 1980, when NASA would initiate development of Skylab refurbishment kits, a 10-foot-long Docking Adapter (DA), and a 25-KW Power Module (PM). The DA would include at one end an Apollo-type probe docking unit for attaching it to Skylab's front port and at the other end an Apollo-Soyuz-type androgynous unit to which Shuttle Orbiters and the PM could dock.

The first refurbishment kit and the DA would reach Skylab on board a Shuttle Orbiter in January 1982. During the same mission, spacewalking Shuttle astronauts would fold two of the four ATM solar arrays to improve clearance for visiting Orbiters and would retrieve the meteoroid experiment the Skylab 4 astronauts had left on the ATM.

A second Shuttle visit in August 1983 would bring additional refurbishment kits and would repair Skylab's damaged cooling system plumbing. As time allowed, the Phase II crews would perform undefined "simple passive experiments" on board Skylab and would collect samples of its structure for analysis on Earth.

Phase III would begin in March 1984 with delivery of the PM and any remaining refurbishment kits, the MSFC engineers told Yardley. Using the Shuttle's Remote Manipulator System robot arm, astronauts would lift the PM from the Orbiter's payload bay and turn it 180° so that it protruded forward well beyond the Orbiter's nose. They would then dock one of the PM's three androgynous docking units to an identical unit at the front of the Orbiter's payload bay. The Shuttle would use another of the PM's docking units to dock with the DA on Skylab.

Following docking with Skylab, the astronauts would deploy the PM's twin solar arrays and thermal radiators, link it to Skylab's systems by cables extended through open hatchways or installed on the hull during spacewalks, and power up the PM's three CMGs to replace Skylab's crippled attitude control system. The Orbiter would then undock from the PM, leaving it attached permanently to Skylab, and NASA would declare the revived and expanded Orbital Workshop to be fully habitable.

Phase III would continue with the first in a series of 30-to-90-day missions aboard Skylab. During these, a Shuttle Orbiter carrying a Spacelab module in its cargo bay would remain docked with the Orbital Workshop. The astronauts would work in the Spacelab module, take advantage of Skylab's large pressurized volume to perform "simple experiments" requiring more room than Shuttle and Spacelab could provide (for example, preliminary space construction experiments), and begin building up stockpiles of food, film, clothing, and other supplies on board. Another 30-to-90-day mission would see the astronauts refurbish and use selected Skylab science experiments, install new experiments based on Spacelab experiment designs, and stockpile more supplies. Between these missions, the new and improved Skylab would fly unmanned.

The MSFC engineers told Yardley that the volume available to a crew on board a Shuttle Orbiter without a Spacelab module in its payload bay would total only 1110 cubic feet. Adding a Spacelab would increase that to about 5100 cubic feet. This was, however, less than half the pressurized volume of Skylab. For a mission including a Shuttle Orbiter, Spacelab module, and Skylab, the total volume available to the crew would exceed 16,400 cubic feet.

They were not specific about what Skylab would be used for when Phase IV began in mid-1986, though they did offer several intriguing possibilities. Shuttle Orbiters might, for example, attach Spacelab modules and experiment pallets to the third docking port on the PM. A Shuttle External Tank might be joined to Skylab to serve as a strongback for large-scale space construction experiments using a mobile "space crane." The experiments might include construction of a large space power module or a multiple beam antenna. A new "floor" might be assembled within Skylab, enabling it to house up to nine astronauts. As NASA developed confidence in the revived space laboratory's health, manned missions on board Skylab without a Shuttle Orbiter present might commence, leading to permanent manning and "support [of] major space operations."

The MSFC engineers did not estimate the cost of Phases I and IV of their plan, though they did provide a (perhaps optimistic) pricetag for Phases II and III. Their estimate did not include Space Shuttle transportation and contractor study costs. In Fiscal Year (FY) 1980, NASA would spend $2 million each on Phases II and III. This would climb to $5 million for Phase II and $3.4 million for Phase III in FY 1981. FY 1982, the plan's peak funding year, would see $4.5 million spent on Phase II and $10.2 million spent on Phase III. In FY 1983, NASA would spend $2.5 million to close out Phase II and $12 million to continue Phase III. The following year it would spend $9.1 million on Phase III. Phase III closeout in FY 1985 would cost $4.5 million. Phase II would cost a total of $14 million, while the more ambitious Phase III would total $41.2 million. Phases II and III together would cost $55.2 million.

MSFC's presentation to Yardley concluded with a call for more in-house and contractor studies in FY 1978. McDonnell Douglas and Martin Marietta subsequently began more detailed Skylab reuse studies, the former under supervision of NASA Johnson Space Center in Houston, Texas, and the latter under MSFC supervision. The Martin Marietta study for MSFC will be discussed in a forthcoming post.

Skylab Reuse Study Presented to Mr. Yardley by MSFC, November 16, 1977.

Skylab-Salyut space laboratory (1972)

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On May 14, 1973, the five F-1 engines at the base of the last Saturn V rocket to fly ignited, engulfing Pad 39A at Kennedy Space Center in orange flame and gray smoke. Seconds later, the hold-down arms on the launch pad swung clear, and the rocket began its thundering ascent.

The last Saturn V bore the Skylab Orbital Workshop, a temporary space station, into a 435-kilometer-high orbit inclined 50° relative to Earth's equator. Skylab, the last vestige of the Apollo Applications Project, comprised the large-diameter cylindrical Orbital Workshop (OWS) with two wing-like solar arrays, the small-diameter cylindrical Airlock Module (AM) and Multiple Docking Adapter (MDA), and the truss-mounted Apollo Telescope Mount (ATM) with four solar arrays arranged in a "windmill" formation (top image above). The OWS, for which McDonnell Douglas was prime contractor, was a converted Apollo Saturn S-IVB stage.

Skylab had a mass of about 100 tons at launch. Fully deployed in orbit, it measured about 36 meters long. The station included 347 cubic meters of living and working space pressurized to 5 pounds per square inch (psi). Skylab reached orbit unmanned and fully stocked with oxygen, nitrogen, water, food, clothing, film, spare parts, and other expendables. Apollo Command and Service Modules (CSMs) launched on two-stage Saturn IB rockets delivered to Skylab three-man crews and a small amount of cargo.

Skylab was not the Earth's first space station; that honor belonged to the Soviet Union's Salyut 1. Salyut 1 had reached orbit on top of a Proton rocket, the Soviet equivalent of the Saturn IB, on April 19, 1971. The station was much smaller than Skylab, with a mass at launch of only 20 tons. Built from parts developed for the Almaz military space station and the Soyuz piloted spacecraft, Salyut 1 measured 15.8 meters in length and contained 90 cubic meters of living and working space pressurized to 15 psi (that is, approximately Earth sea-level pressure). Like Skylab, Salyut 1 reached orbit unmanned and stocked with expendables. Soyuz ferries delivered three-man crews and a limited quantity of cargo to a single port at Salyut 1's front end.

At the time Salyut 1 flew, the U.S. and the Soviet Union were negotiating toward a U.S. spacecraft docking with a Soviet spacecraft. By the end of 1971, the sides had settled on an Apollo CSM docking with a Salyut station. The spacecraft would each carry a new-design International Docking Mechanism (IDM).

In April 1972, however, Soviet negotiators declared that the Salyut design could not easily be modified to include a second docking port. They suggested that a CSM dock instead with a modified Soyuz. On May 24, 1972, at a summit meeting in Moscow, U.S. President Richard Nixon and Soviet Premier Alexei Kosygin signed the Space Cooperation Agreement, an international treaty that called for a wide range of cooperative ventures, including an Apollo-Soyuz docking. On June 30, 1972, NASA named the new cooperative program the Apollo-Soyuz Test Project (ASTP). The Soviets called it Soyuz-Apollo.

A week earlier, a McDonnell Douglas Astronautics Company team had pitched to NASA a cooperative space mission much more ambitious than either Apollo-Soyuz or Apollo-Salyut. The team proposed a docking between the backup Skylab (Skylab B), a Salyut, an Apollo CSM, and a Soyuz ferry (bottom three images above). The resulting "cooperative space laboratory" would "address world needs" and "provide identifiable benefits from space" and "mutual technological benefits and cost savings." The U.S.-Soviet crew would perform solar, stellar, and Earth observations, communications technology development, and biomedical studies. Perhaps most important for NASA, Skylab-Salyut would serve as "an evolutionary step between Skylab A and Space Shuttle/Station" that would permit the U.S. space agency to keep its spaceflight teams mostly intact during the projected gap in U.S. piloted flights between ASTP in 1975 and the planned first Shuttle flight in 1979.

The company proposed a 140-day Skylab-Salyut mission in mid-1976. Skylab B would launch into a 435-kilometer-high orbit inclined 51.6° relative to the equator; that is, at Skylab A's orbital altitude but at the Soviet Union's preferred orbital inclination. A CSM bearing three astronauts would launch the following day and dock with an Apollo-type port on the side of the Skylab B MDA. The Soviet Union would then launch a Salyut into a 240-kilometer-high orbit at 51.6° of inclination, followed by an IDM-equipped Soyuz ferry bearing three cosmonauts. The Soyuz would dock with the Salyut forward port, which would also carry an IDM.

McDonnell Douglas cited published Soviet data when it assumed that the Salyut's propulsion system could be used to match orbits with Skylab B. As the Salyut-Soyuz combination approached the U.S. station, two cosmonauts would undock from the Salyut in the Soyuz and dock with an IDM-equipped port on the side of the Skylab MDA opposite the CSM. The lone cosmonaut on board the Salyut would then pilot it to a docking with the IDM-equipped Skylab forward port.

The cosmonauts and astronauts would work together on board Skylab-Salyut for at least 24 days (the longest period a Soyuz had operated in Earth orbit as of June 1972). The three cosmonauts would then undock in the Soyuz and return to Earth. The Soviets could then launch at least one more crew to the station. After up to 70 days in orbit, the first U.S. crew would return to Earth in its CSM. A second CSM would then deliver a second crew. If they docked immediately after the first crew departed, the second crew could remain on board Skylab-Salyut for up to 70 days.

As noted above, U.S. and Soviet spacecraft provided their crews with different gas mixes and pressures. Astronauts and cosmonauts passing between the two parts of the Skylab-Salyut station might prebreathe to adapt their bodies to the change in pressure and gas mix, though the time required would probably become onerous very quickly. Alternately, the sides could adopt a common atmosphere.

If the international station adopted Skylab's oxygen-rich 5 psi atmosphere, the Salyut and Soyuz would require improved fireproofing and beefed-up thermal control systems to keep its electronics cool in the thin air. If, on the other hand, the Soviet 15 psi pressure were adopted, Skylab B would need substantial structural changes to withstand the increased pressure and extra tanks of oxygen and nitrogen to make up for air lost through accelerated leakage. The CSM could not withstand 15 psi without suffering damage, so would need to remain isolated from the Skylab/Salyut/Soyuz cluster. McDonnell Douglas suggested that a small airlock for prebreathing be placed in the MDA for CSM access.

The company then proposed a compromise 8 psi atmosphere slightly rich in oxygen. The CSM could withstand this pressure, it explained, and the modifications both sides would need to make would be roughly equivalent in magnitude.

Some modifications would be required no matter which atmosphere was adopted. McDonnell Douglas assumed that Skylab B would provide all attitude control for the international station. To meet this requirement, NASA would need to equip it with control moment gyros 30% more capable than those planned for Skylab A. The Skylab B MDA structure would have to be beefed up to handle greater docking loads, as would its ATM trusses. In addition, a new thermal radiator would be needed to dissipate the heat produced by the three Soviet cosmonauts when they worked on board Skylab B. McDonnell Douglas proposed that this be added to the Fixed Airlock Shroud at the front of the OWS, close to the MDA.

Possible Salyut changes would include enlarged solar arrays; these might be needed because the four arrays on the Skylab B ATM would shade the Salyut's forward pair of arrays, reducing the Soviet station's electricity supply by up to a quarter. McDonnell Douglas assumed that Skylab B and the Salyut would not share electricity, so the U.S. would be unable to make up the difference. The company added, however, that, by relieving the Salyut of attitude control responsibilities, Skylab B might save it as much electricity as it took away.

Skylab B never reached orbit; in fact, it became an exhibit in the National Air and Space Museum in Washington, DC. Skylab A - redesignated Skylab 1 - suffered damage about a minute after launch as its meteoroid shield tore away, then lost one of its twin OWS solar arrays shortly after attaining orbit. NASA engineers hurriedly fashioned specialized tools and trained the Skylab 2 crew in their use. Astronauts Pete Conrad, Joe Kerwin, and Paul Weitz reached Skylab on May 25, 1973, and succeeded in making it habitable and functional. They spent a total of 28 days in space. The Skylab 3 crew (Alan Bean, Jack Lousma, and Owen Garriot) spent 59 days on board the repaired station. After 84 days in space, the Skylab 4 crew (Gerald Carr, Edward Gibson, and William Pogue) undocked from Skylab on February 8, 1974. The derelict station reentered Earth's atmosphere on July 11, 1979.

A little more than a three years after McDonnell Douglas completed its study, the ASTP mission commenced. On July 15, 1975, the Soyuz 19 spacecraft ascended to Earth orbit, followed seven hours later by the final Apollo CSM, which had no official numerical designation. On board Soyuz 19 were Alexei Leonov, the first man to walk in space, and Soyuz 6 veteran Valeri Kubasov. The ASTP Soyuz carried an "APDS-75" international docking unit with three outsplayed guide "petals." Gemini and Apollo veteran Thomas Stafford and rookie astronauts Vance Brand and Donald Slayton rode aboard the ASTP CSM.

After reaching an unusually low 188-by-228-kilometer orbit - required because the Soyuz could not climb higher - the ASTP CSM detached from the Saturn IB S-IVB stage that had injected it into orbit and turned 180°. It then docked with an Apollo-type port on the Docking Module (DM). The DM, which had reached orbit within a streamlined shroud between the CSM's large engine bell and the top of the S-IVB stage, included an international docking system and an airlock to enable the ASTP crews to move between the U.S. and Soviet spacecraft atmospheres without harm. After they extracted the DM from the spent S-IVB, the American ASTP crew maneuvered their spacecraft toward a rendezvous with Soyuz 19.

The ASTP CSM docked with Soyuz 19 on July 17, 1975. Following two days of ceremonies and mutual experiments, the two spacecraft undocked, redocked with Soyuz 19 playing the active role, and then went their separate ways. Soyuz 19 landed in Soviet Kazakhstan on July 21, and the ASTP CSM splashed down in the Pacific Ocean on July 24, six years to the day after Apollo 11 returned from the moon. It was the last time American astronauts flew in space until the first Space Shuttle flight in April 1981.

In 1974, NASA studied a 1977 ASTP mission. At about the same time, work began toward a Shuttle-Salyut docking in the early 1980s (images below). New cooperation was hampered by U.S. domestic politics: NASA felt unable to commit to a new international piloted flight ahead of the November 1976 presidential election.

President Jimmy Carter's Administration renewed the Space Cooperation Agreement in May 1977. In November of that year, NASA and Soviet engineers met in Moscow to discuss the Shuttle-Salyut mission. The sides examined using the Shuttle to deliver an experiment module to a Salyut and traded engineering data.

By then, Salyut 6 was in orbit. The new station included a second, aft-mounted, docking port. In January 1978, NASA completed a preliminary Shuttle-Salyut mission plan which saw the Shuttle dock with the Salyut front port while a Soyuz was docked at its aft port.

U.S.-Soviet relations gradually soured, however. A Shuttle-Salyut technical meeting planned for April 1978 was indefinitely postponed. In September 1978, NASA ceased Shuttle-Salyut planning pending the outcome of an interagency review of U.S.-Soviet space cooperation. The Soviet invasion of Afghanistan in December 1979 subsequently halted for a decade almost all discussion of dockings between U.S. and Soviet piloted spacecraft, though superpower cooperation with a lower profile - for example, the Cosmos biosatellite program - continued.

US/USSR Cooperative Space Laboratory (Skylab/Salyut), McDonnell Douglas Astronautics Company Eastern Division, 23 June 1972.

Mir Hardware Heritage, NASA RP 1357, David S. F. Portree, March 1995.

Thirty Years Together: A Chronology of U.S.-Soviet Space Cooperation, NASA CR 185707, David S. F. Portree, February 1993.

Skylab News Reference, NASA Office of Public Affairs, March 1973.

Basic Data of the Scientific Orbital Station "Salyut," USSR, no date (1971?).

Apollo-Soyuz Test Project Information for Press, USSR/NASA, 1975.

Viking on the moons of Mars (1972)

2011-12-06T05:34:00.000-08:00

In June 1972, NASA's Langley Research Center (LaRC) in Hampton, Virginia, hired Martin Marietta Corporation to look at using spacecraft based on the planned Viking Mars lander and orbiter designs to explore the martian moons Phobos and Deimos (top and middle images above, respectively; both from NASA's Mars Reconnaissance Orbiter). LaRC managed Project Viking, which aimed to launch two lander/orbiter combinations toward Mars in 1975, while Martin Marietta was prime contractor for the Viking lander (bottom image above). The Jet Propulsion Laboratory in Pasadena, California, built the Mariner-based Viking orbiter.

The proposed missions were in part a response to declared Soviet space plans. The Soviets were active at this time telling the world that they had never meant to land a man on the moon; that they had opted instead for cheaper robots that would not place lives at risk. They claimed that soon they would dispatch robot orbiters, landers, sample-returners, and rovers throughout the Solar System.

Phobos and Deimos revolve about Mars in circular equatorial orbits. Phobos completes one orbit in about 7.5 hours at an altitude of about 5980 kilometers, while Deimos orbits in about 30 hours at 20,070 kilometers. Phobos measures 21 kilometers by 25 kilometers, and Deimos is about half as large. Small size means low gravity; Phobos has only about 0.1% as much the surface gravity as Earth. The Mariner VII spacecraft glimpsed Phobos during its fast Mars flyby in 1969, and the Mariner 9 Mars orbiter returned the first detailed images of both moons in November 1971, while Martin Marietta's study was underway.

LaRC directed the company to assume that its Viking-based Phobos/Deimos missions would depart Earth in the 1979 and 1981 Earth-Mars minimum-energy transfer opportunities. The study report described several Phobos/Deimos spacecraft designs. The first, the baseline Phobos/Deimos landing spacecraft, would comprise a heavily modified Viking lander and a Viking orbiter with tanks carrying 38% more propellants than the Viking 1975 design (Martin Marietta called this a "38% Stretch Orbiter"). Total weight at Earth-orbit departure would be about 3600 kilograms in 1979, of which the lander would account for 482 kilograms.

Upon arrival at Mars, the orbiter would fire its rocket engine to slow down and place itself and the attached lander into an elliptical equatorial "capture orbit" around Mars. The spacecraft would then maneuver into an elliptical, 15-hour "observation orbit." The apoapsis (high point) of this orbit would reach Deimos' orbit, while its periapsis (low point) would dip inside the orbit of Phobos. The spacecraft would repeatedly fly past Phobos and Deimos, gathering data at each encounter so that scientists on Earth could decide which moon most warranted in-depth exploration. Controllers would then command the spacecraft to match orbits with the moon selected.

The lander would separate from the orbiter and move toward its target using Viking lander attitude-control thrusters. It would set down on three spidery legs and deploy 82 kilograms of instruments, including a seismometer, a surface sample auger, and a boom-mounted camera. The lander would be able to hop across the surface in the weak gravity by firing its thrusters; an alternate mobility scheme would employ spindly wheels at the ends of the legs.

Martin Marietta proposed an alternate baseline mission in which the Viking orbiter would land on the target moon. This more efficient "landed orbiter" scenario would land about 500 kilograms of science instruments, the company found. Total cost for a baseline Phobos/Deimos landing mission would come to $324 million.

The company targeted its second design, the baseline Phobos/Deimos sample-return spacecraft, for launch in 1981 "to allow more time for additional mission design and hardware development." The sample-return mission would build on experience gained in the 1979 landing mission. Its 3374-kilogram spacecraft would consist of a 38% Stretch Viking orbiter with four legs and a 260-kilogram Earth-return vehicle based on a proposed Venus Pioneer spacecraft design.

The orbiter would land on the target moon, collect a two-kilogram sample, and transfer it to a sample-return capsule inside the Earth-return vehicle. The Earth-return vehicle would then fire its rocket to separate from the landed orbiter and maneuver into a 1500-kilometer-by-95,000-kilometer Mars orbit. There it would trim its orbital plane so the subsequent Mars departure maneuver could place it on course for Earth.

Near Earth, the saucer-shaped sample-return capsule would separate from the Earth-return vehicle. It would enter Earth's atmosphere at up to 12.8 kilometers per second, slow to subsonic speed, and deploy a parachute for a soft landing. The cost of the baseline sample-return mission would total $446 million.

Martin Marietta's third design, the baseline combined Phobos/Deimos landing and Mars landing spacecraft, would comprise a minimally modified Viking lander and a 26% Stretch Viking orbiter. Total weight at Earth-orbit departure would be 4150 kilograms in 1979. For this "Mars + Phobos/Deimos landing" mission, the orbiter would fired its rocket to place itself and the Viking lander into an elliptical equatorial capture orbit about Mars requiring 97 hours to complete, then would release the lander. De-orbiting from the capture orbit would impose restrictions on the lander - it would be able to set down only within 12 degrees of Mars' equator and would need a beefed-up heatshield to withstand greater Mars atmosphere entry velocity.

The orbiter would then maneuver to a 15-hour observation orbit, match orbits with either Phobos or Deimos, and land bearing 62 kilograms of science instruments. Total cost for the baseline combined mission is $441 million.

Martin Marietta also considered Mars + Phobos/Deimos observation orbit, Mars + Phobos/Deimos rendezvous, and Mars + Phobos/Deimos sample-return missions. These "Mars +" missions would, the company estimated, be more cost-effective than Phobos/Deimos missions without Mars landings. A separate Phobos/Deimos landing mission would, for example, cost 80% as much as a Mars landing mission, while a Mars + Phobos/Deimos landing mission would cost only 14% more than a Mars landing mission.

The company then looked at whether there was sufficient interest in the planetary science community to justify missions to the martian moons. It found that there were "no active and forceful champions" of Phobos/Deimos exploration, but added that

we repeatedly found easily excited curiosity and conjecturing among space scientists about the origin and nature of these tiny bodies. This undercurrent of scientific interest, which has been given impetus by the recent returns of Mariner 9, may be the forerunner of well defined and enthusiastically supported recommendations for exploring the moons of Mars. If this is the case, NASA's decision to conduct this study may prove to be a very timely one.

NASA opted not to fund any missions using Viking technology beyond the original pair of Viking spacecraft. Viking 1 left Earth atop a Titan III-E rocket with a Centaur upper stage on August 20, 1975. Viking 2 launched on September 9, 1975. The spacecraft entered Mars orbit on June 19, 1976, and August 7, 1976, respectively. The Viking 1 lander separated from its orbiter and touched down successfully on July 20, 1976; Viking 2's lander followed on September 3, 1976.

While the landers operated on the surface, the orbiters imaged Mars and its satellites. On October 15, 1977, the Viking 2 orbiter passed just 30 kilometers from Deimos, permitting it to image boulders as small as houses and nearly hidden craters on the little moon's surface (top image below). Viking Orbiter 1 beamed to Earth the images forming the Phobos photomosaic below (bottom image) on October 19, 1978.

A Study of System Requirements for Phobos/Deimos Mission, Final Report, Volume I, Summary, Martin Marietta Corporation, June 1972.

Power Extension Package for Shuttle/Spacelab (1981)

2011-12-02T17:05:00.000-08:00

On November 29, 1972, NASA Administrator James Fletcher abolished the Space Station Task Force formed in early 1969 by his predecessor, Thomas Paine, and formed the Sortie Lab Task Force. Fletcher's move acknowledged that the Space Shuttle, conceived originally as a vehicle for transporting crews and cargoes between Earth and an Earth-orbiting space station, would need to become a space station - or, at least, an interim space laboratory that could demonstrate that a space station would be desirable.

Strapped for funds and encouraged by President Richard Nixon to use spaceflight as a vehicle for international cooperation, NASA asked the European Space Research Organization (ESRO) to build a "sortie lab" that could be carried in the Shuttle Orbiter's payload bay. In August 1973, ESRO agreed to build the sortie lab, which became known as Spacelab (top image above).

Spacelab would provide scientists with ample pressurized volume in which to conduct research, but it would rely on limited resources - for example, electricity - provided by the Shuttle Orbiter. Orbiter electricity came from a trio of liquid oxygen/liquid hydrogen fuel cells that could together generate 21 kilowatts continuously for just seven days. Of this, 14 kilowatts were required for Orbiter systems. The Orbiter could thus supply seven kilowatts to Spacelab. Of these, between two and five kilowatts would be needed for basic Spacelab systems, leaving a paltry two to five kilowatts for Spacelab experiments.

In 1978, NASA's Johnson Space Center (JSC) launched the Orbital Service Module Systems Analysis Study, which looked into ways that the Space Shuttle Orbiter could be augmented to enable it to better support Spacelab research. An early product of the study was the Power Extension Package (PEP) concept.

The PEP concept was also linked - however tenuously - with NASA's extensive efforts in cooperation with the U.S. Department of Energy to justify the construction of enormous Earth-orbiting solar power satellites. It was portrayed as an experience-building experimental test-bed for solarsat technology in JSC director Christopher Kraft's Von Karman Lecture to the 15th meeting of the American Institute of Aeronautics and Astronautics in July 1979.

The PEP Project Office (PEPPO) at JSC pitched the PEP in a brief report published one month before the first Space Shuttle flight (STS-1; April 12, 1981). The PEPPO envisioned the PEP as a "kit" that could be installed easily in the Shuttle Orbiter payload bay over the tunnel that would link the Orbiter Mid-Deck with the Spacelab.

One hour after launch from Earth, an astronaut on the Flight Deck would use the Canada-built Remote Manipulator System (RMS) robot arm (bottom image above) to grapple the PEP's Array Deployment Assembly (ADA) and extend it out over the Orbiter's side. The ADA would then unroll a pair of light-weight solar array wings that together would measure more than 100 feet wide. PEP deployment would require about 30 minutes.

The PEP arrays would track the Sun automatically no matter how the Orbiter was oriented, so almost no astronaut intervention would be needed after they were deployed. The RMS and arrays would be sufficiently sturdy to remain deployed during Orbiter attitude-control maneuvers, but the crew would need to stow them before Orbital Maneuvering System burns lest acceleration cause damage.

The twin arrays would generate a total of 26 kilowatts of electricity. A cable built into the RMS would carry the electricity from the ADA to the PEP's Power Regulation and Control Assembly (PRCA) in the payload bay. The PRCA would then distribute it to the Orbiter's electrical system.

The three Orbiter fuel cells would "idle" while the PEP arrays were in sunlight. Each would generate one kilowatt of electricity, bringing the total available on board to 29 kilowatts. Fifteen kilowatts would be available for Spacelab, of which between 10 and 13 kilowatts could be devoted to experiments.

Keeping the Spacelab electricity supply constant throughout each 90-minute orbit of the Earth would require that Orbiter fuel cell output ramp up rapidly from three to 29 kilowatts as the PEP arrays passed into darkness over Earth's night side. To achieve this output, each fuel cell would need to exceed its normal maximum by nearly three kilowatts. The fuel cells would then return to idle as the PEP arrays passed again into sunlight. Though it would almost certainly place unusual demands on the fuel cells, the PEPPO judged this approach to be "feasible."

A PEP could extend Orbiter/Spacelab endurance in Earth orbit to 11 days, the PEPPO estimated. If other Orbiter resources (for example, life support consumables) could be augmented, then mission duration might be stretched to 45 days.

The PEPPO explained that it jointly managed PEP solar cell development with NASA's Lewis Research Center. Industry involvement in the PEP project was, it added, already "extensive," with several companies working on small NASA contracts or funding PEP-related work themselves. It estimated that the PEP could reach space in 1985 at a total cost of about $150 million.

Power Extension Package (PEP) Concept Summary, JSC-AT4-81-081, NASA Johnson Space Center, PEP Project Office, March 1981.

From the author: Top 10 Articles

2011-11-28T20:46:00.000-08:00

Sagan & Swan on Voyager landing sites (1965)

2011-11-27T15:05:00.000-08:00

Until the 1980s, most U.S. automated space explorers bore names connoting ventures into unknown parts - Explorer, Pioneer, Ranger, Surveyor, Mariner, and Voyager. Most people today identify the last of these names with the spectacularly successful pair of outer Solar System flyby spacecraft launched in the late 1970s. There was, however, an earlier Voyager program. First proposed in 1960 as a follow-on to the planned Mariner planetary flyby program, the original Voyager aimed to explore Venus and (especially) Mars using orbiters and landing capsules.

Carl Sagan, an assistant professor of astronomy at Harvard, and Paul Swan, Senior Project Scientist at Avco Corporation, published results of a study of possible Voyager Mars landing sites in the January-February 1965 issue of Journal of Spacecraft and Rockets. For their study, they invoked a Voyager design Avco had developed in 1963 on contract to NASA Headquarters. The "split-payload" design comprised an orbiter "bus" based on the Jet Propulsion Laboratory's Mariner (or proposed advanced Mariner-B) design and a landing capsule shaped like the Apollo Command Module. Bus and capsule would leave Earth together on a Saturn IB rocket with an "S-VI" upper stage (a modified Centaur stage).

The Voyager lander would be sterilized to prevent biological contamination of Mars. Near Mars it would separate from the orbiter, enter the martian atmosphere, and float to a gentle touchdown suspended from a parachute. The Avco design included no landing rockets, which meant that more lander mass could be devoted to instruments for exploring the planet. The lander would operate on Mars for at least 180 days. The Voyager orbiter, meanwhile, would fire rockets to slow down so that Mars's gravity could capture it into a polar orbit, from which it would image the entire martian surface and serve as a radio relay for the lander.

Swan and Sagan noted that operational constraints would limit possible Mars landing sites. For example, the orbiter and Earth would need to rise at least 10° above the horizon at the landing site to permit daily radio communication sessions, and the Sun would need to be rise at least 10° above the horizon so that the lander's solar-powered science instruments could function properly. Such constraints would combine to create landing "footprints" that would vary widely depending on the Earth-Mars transfer opportunity used. The footprint for the 1969 minimum-energy opportunity, for example, would take the form of a north-pointing wedge centered on 270° longitude and spanning from 70° south to 60° north latitude.

Avco's Voyager lander was designed so that it could be targeted to specific regions within such footprints, Sagan and Swan noted. They proposed that exobiologically interesting sites be accorded top priority in Voyager lander site selection. Sagan and Swan then looked at possible exobiologically interesting areas accessible to the Voyager landers launched during the 1969, 1971, 1973, and 1975 minimum-energy opportunities.

Their list of such sites was, of course, based entirely on Earth-based telescopic observations (top image above), for no spacecraft had yet visited Mars. They also used surface feature names that had been assigned by telescopic observers (bottom image above); these names would be superseded soon after the 1971-1972 Mariner 9 Mars orbiter mission.

Sagan and Swan described the "wave of darkening" observed since the 19th century. The "wave" was regularly observed spreading from the pole to the equator in the martian springtime hemisphere. When they wrote their paper, it was widely interpreted as indicative of martian water, atmospheric circulation, and vegetation. Theory had it that, as the polar ice cap melted, atmospheric moisture increased and circulated toward the equator. Hardy plants then darkened as they absorbed the moisture from the thin air.

The first two Voyager landers would reach Mars on October 31, 1969, during springtime in the planet's southern hemisphere. The wave of darkening would be near its peak, making it the best biological exploration opportunity until 1984. Top priority landing sites would include the northern hemisphere regions Solis Lacus and Syrtis Major, which Sagan and Swan described as the "[d]arkest of the Martian dark areas." On the landing date, both regions would lie at the northern extreme of the southern hemisphere darkening wave and would be relatively warm.

Voyager spacecraft launched in the 1971 minimum-energy opportunity would arrive at the planet on December 14, 1971. Swan and Sagan noted that the 1971 opportunity would need the least amount of energy of any opportunity they considered, and suggested two possible ways of taking advantage of this. Four landers (two per orbiter) could reach Mars as the southern hemisphere wave of darkening faded. Top priority landing sites for this approach would be the southern polar cap, southern hemisphere dark areas Mare Cimmerium and Aurorae Sinus, and Lunae Palus in the north.

Alternately, the 1971 Voyager missions could use a higher-energy path to deliver two landers to Mars as the southern hemisphere darkening wave began. "Thus," they wrote, "the exobiologically highly desirable characteristics of the 1969 arrival [could] be completely duplicated in the 1971 launch period."

In the 1973 opportunity, which would see a landing on February 24, 1974, two landers would explore Mars's deserts and "the so-called canal features." The accessible landing sites would be relatively cold on the arrival date. Top-priority sites would include Propontis, a region containing a "typical Martian canal," and Elysium, a "near circular anomalous bright region of 'pinkish' coloration" in the northern hemisphere.

Sagan and Swan proposed that two Voyager landers leave Earth during the 1975 minimum-energy opportunity. They would land on Mars on August 28, 1976. Top-priority sites would include the northern polar cap and Mare Cimmerium, where the wave of darkening would reach its peak as the 1975 landers arrived.

Swan and Sagan looked briefly at the possibility of launching Voyager spacecraft on the powerful Saturn V rockets that were under development for the Apollo manned lunar program at the time they wrote their paper. They found that "superior site selection could be performed" if the giant moon rocket were applied to Mars exploration. In fact, their "preliminary calculations" showed that "the landing footprints for all post-1971 opportunities may be made to superimpose on the [highly favorable] 1969 footprint" if the Saturn V were used.

The first successful automated Mars spacecraft, 261-kilogram Mariner IV, departed Cape Kennedy, Florida, on an Atlas-Agena rocket on November 28, 1964, and flew past Mars on July 14-15, 1965, six months after Sagan & Swan's paper saw print. Mariner IV revealed a cratered, distressingly moon-like Mars with an atmosphere ten times less dense than expected. The 21 grainy images of the planet the little spacecraft beamed to Earth revealed no signs of water or life. The Avco Voyager design Sagan & Swan had invoked for their study would have depended entirely on parachutes to descend to a soft landing; Mariner IV showed that, while parachutes might still be used, heavy landing rockets would also be needed to enable a soft landing.

This new operational constraint contributed to NASA's October 1965 decision to employ the Saturn V as Voyager's launcher. At least as important as the new Mars atmosphere data in this decision was, however, the desire to find new tasks for the Saturn V after it had done its part to place a man on the moon. In 1964-1965, at the request of president Lyndon B. Johnson, NASA had begun to plan its post-Apollo future. In January 1965, the Future Programs Task Group, a body appointed by NASA Administrator James Webb, recommended that the post-Apollo NASA program be based on Apollo-Saturn hardware.

Accordingly, in August 1965, NASA Headquarters formed the Saturn-Apollo Applications (SAA) Program Office. By mid-1966, SAA planners expected to fly as many as 40 manned missions using Saturn-Apollo hardware beginning in 1968.

At about the same time, NASA began high-level agency-wide studies of Saturn V-launched manned Mars/Venus flyby missions - what Charles Townes, chair of the President's Science Advisory Committee, dubbed a "manned Voyager" program. The first of these missions was expected to leave Earth in 1975.

Despite Sagan & Swan's endorsement of the Saturn V, the fledgling planetary science community harbored mixed feelings about the decision to launch Voyager spacecraft on the giant rocket. The decision in December 1965 to postpone the first Voyager mission to the 1973 Mars-Earth transfer opportunity reinforced these misgivings. Combined with the post-Mariner IV redesign, the switch to the Saturn V drove the estimated Voyager cost-per-mission past $2 billion. The high cost made the program increasingly vulnerable as NASA funding reached its Apollo-era peak in 1965-1966 and began a speedy decline.

In August 1967, in the wake of the Apollo 1 fire, Congress killed Voyager and manned flyby mission studies and slashed funding for the Apollo Applications Program (AAP), as SAA had become known. The manned flyby program all but disappeared from NASA's collective memory and AAP shrank rapidly to become the Skylab Program. In October 1970, NASA permanently closed the Saturn V assembly line, which had been on standby since 1968. The last Saturn V to fly launched the Skylab Orbital Workshop in May 1973.

Voyager, for its part, rose again. In fact, one might argue that it rose again twice. In October 1967, NASA officials, citing Soviet planetary ambitions, met with Congressional leaders to propose a new NASA robotic program for the 1970s. In the new plan, which Congress first funded in 1968, Viking replaced Voyager. Like the Avco Voyager, Viking comprised a lander and a Mariner-derived orbiter; unlike Avco's Voyager, the Viking orbiter was meant to retain its lander until after it had captured into Mars orbit. The Viking Program's Titan IIIE-Centaur launch vehicle was approximately equivalent to Saturn IB-Centaur in capability.

Funding shortfalls pushed launch of the twin Vikings from 1973 to 1975. In July-August 1976, the Viking landers became the first and second spacecraft to land successfully on Mars.

Meanwhile, in 1972, Congress approved the Mariner Jupiter-Saturn (MJS) flyby mission. The twin MJS spacecraft were christened Voyager 1 and Voyager 2 and launched in 1977 (top image below). Voyager 1 flew past Jupiter (1979) and Saturn (1980); Voyager 2 flew past Jupiter (1979), Saturn (1981), Uranus (1986), and Neptune (1989). To date, Voyager 2 remains the only spacecraft from Earth to have visited Uranus and Neptune.

The Voyagers continue to operate more than 30 years after launch and more than 50 years after the Voyager name was first proposed. Voyager 1 is the most distant human-made object; at this writing it is about 119 Astronomical Units (AUs) out (one AU = the Earth-Sun distance of 93 million miles). Sunlight needs more than 16 hours to reach Voyager 1. Both Voyagers have entered a poorly understood borderland called the heliosheath; Voyager 1 is expected to cross the heliopause and enter interstellar space before 2015 (bottom image below).

Martian Landing Sites for the Voyager Mission, P. Swan and C. Sagan, Journal of Spacecraft and Rockets, Volume 2, Number 1, January-February 1965, pp. 18-25.

Combining LM Shelter delivery & lunar polar orbit mapping (1966)

2011-11-21T20:59:00.000-08:00

Long before NASA reached the moon, the civilian space agency's managers and engineers began to look at ways of using Apollo lunar hardware in non-lunar missions. In April 1963, for example, the Manned Spacecraft Center (MSC) in Houston awarded North American Aviation (NAA), prime contractor for the three-man Apollo Command and Service Module (CSM) spacecraft (top image above), with a contract to study modifying the CSM to serve as a crew transport and logistics resupply vehicle for a 24-man Earth-orbiting space station (top link below).

On February 18, 1965, George Mueller, NASA Associate Administrator for Manned Space Flight, told the U.S. House of Representatives Committee on Science and Astronautics that Apollo-derived hardware would enable NASA "to perform a number of useful missions. . .in an earlier time-frame than might otherwise be expected" and at a fraction of the cost of developing wholly new spacecraft. He explained that NASA's program for applying Apollo hardware to new missions "would follow the basic Apollo manned lunar landing program and would represent an intermediate step between this important national goal and future manned space flight programs." At the time he testified, the first manned lunar landing attempt was slated for late 1967 or early 1968.

Six months later, in August 1965, Mueller established the Saturn-Apollo Applications (SAA) Office at NASA Headquarters. The new organization quickly began efforts to define the SAA Program's hardware requirements and mission manifest. At about the same time, SAA began to be referred to as the Apollo Applications Program (AAP), the name by which it is best known today.

In late January 1966, Mueller wrote to the directors of MSC, the Marshall Spaceflight Center (MSFC), and Kennedy Space Center, the three main manned space centers, to sum up SAA's evolving objectives. He told them that, in addition to preparing NASA for its next Apollo-scale space goal - whatever that might be - SAA would provide immediate returns in areas as diverse as air pollution control, Earth-resources remote sensing, improved weather forecasting, materials science, and communications satellite repair.

By March 1966, the SAA Program Office had compiled a list of potential new missions for Apollo hardware. From MSC and NAA came proposals for CSM missions in low-Earth orbit (LEO), geosynchronous orbit, and lunar orbit, some of which would last for up to 45 days. MSFC, drawing on plans put forward by its director, Wernher von Braun, proposed that spent Saturn IB S-IVB second stages serve as pressurized "workshops" in LEO. Apollo Lunar Module (LM) (bottom image above) prime contractor Grumman suggested that LMs without legs or ascent engines serve as scientific instrument carriers and mini-laboratories. The company also proposed manned and unmanned LM variants for two-week lunar surface stays. All of these vehicles would reach space atop Apollo Saturn IB and Saturn V rockets, some of which might be uprated for increased payload capacity (middle link below).

In its early SAA planning, NASA referred to SAA missions by their launch vehicle designations. The second, third, and fourth Saturn V-launched SAA missions were called AS-511, AS-512, and AS-513 because they would use the 11th, 12th, and 13th Saturn V rockets purchased for Apollo. SAA planners assumed that, as soon as Apollo achieved its goal of a man on the moon, all remaining Apollo hardware would be released to the SAA Program.

AS-511 would be a CSM-LM lab mission to map the moon from lunar polar orbit. Its three-man crew would operate cameras and mapping sensors mounted on the LM lab.

AS-512 would see a manned CSM deliver an unmanned LM Shelter to near-equatorial lunar orbit. The LM Shelter would undock and descend automatically to a pre-selected landing site. The three astronauts would then ignite their CSM's Service Propulsion System (SPS) main engine to leave lunar orbit and return to Earth.

AS-513, the first SAA manned moon landing mission, would launch less than three months after AS-512. Two astronauts would land in an LM Taxi near the LM Shelter while a third astronaut remained in lunar orbit on board an Extended Capability CSM (XCSM). The surface astronauts would place the LM Taxi in "hibernation" and use the LM Shelter as their base of operations for 14 days of exploration (bottom link below).

The SAA Program Office solicited inputs from Bellcomm, the NASA Headquarters advance planning contractor. On April 4, 1966, Bellcomm engineer P. W. Conrad completed a brief memorandum in which he proposed merging the AS-511 and AS-512 missions.

Conrad wrote that AS-511 did not in fact need an LM lab; its CSM could carry the cameras, film, sensors, and magnetic tape it would need for lunar mapping. He noted also that, in the SAA Program plan, the AS-512 CSM would be a mere "escort" for the LM Shelter, leaving its crew with relatively few duties. A mission in which a CSM bearing mapping instrumentation carried the LM Shelter to the moon would keep its crew productively occupied, Conrad argued, and would free up a Saturn V, CSM, and LM lab for other SAA missions.

He examined two possible profiles for the combined mission. In the first, which Conrad called "direct descent," the CSM would release the unmanned LM Shelter en route to the moon immediately following its last SPS course-correction burn. The LM Shelter would fall toward the moon without entering orbit. Fifty thousand feet above its target landing area, it would automatically ignite its Descent Propulsion System (DPS) to decelerate, hover, and land.

The manned CSM, meanwhile, would pass over one of the lunar poles and fire its SPS behind the moon to perform Lunar Orbit Insertion (LOI); that is, to slow down so that the moon's gravity could capture it into polar orbit. If it were a Block II CSM with 14-day endurance, it would orbit the moon for from five to eight days. If an XCSM, it would orbit for up to 28 days.

As the CSM orbited, the moon would revolve beneath it, so that its ground track would not repeat for at least 14 days; that is, until half a lunar day-night period had passed. The mission would be timed so that the CSM and the terrain it mapped would remain in daylight throughout the lunar-orbital portion of the mission. At the planned end of its time in lunar polar orbit - or sooner, if some fault developed that required an early lunar departure - the CSM would ignite its SPS behind the moon to begin its journey back to Earth.

Conrad's second combined mission profile would see the LM Shelter remain docked to the CSM until some time after LOI. The CSM would ignite its SPS to slow itself and the LM Shelter so that the moon's gravity could capture the docked spacecraft into polar orbit, then its crew would turn its cameras and sensors toward the moon.

As the CSM and LM Shelter orbited, the moon would revolve beneath them, so that within a few days of LOI the LM Shelter's target site would move into position for a landing. The LM Shelter would then undock from the CSM over the moon's Farside hemisphere, automatically ignite its DPS roughly 180° of longitude from its Nearside landing site to begin descent, then fire it again close to the landing site to carry out powered descent, hover, and landing. The CSM astronauts, meanwhile, would continue their mapping mission.

Both scenarios had advantages and disadvantages, Conrad acknowledged. Direct descent would require that the LM Shelter carry extra landing propellants, which might limit the mass of exploration equipment and life support consumables it could place on the moon. In addition, the LM Shelter's DPS would not be available as a backup or supplement for the SPS if an abort were declared before LOI or in lunar orbit.

On the plus side, relieving the CSM of the LM Shelter's mass ahead of LOI would reduce the quantity of propellants the SPS would need to burn to accomplish LOI. The mass freed up by eliminating propellants could be applied to additional CSM cameras, film, sensors, magnetic tape, and life support consumables.

Retaining the LM Shelter until after LOI would maximize its payload mass, but would also demand more LOI propellants for the SPS. Thus, Conrad explained, the second combined mission profile might lead to a reduction in the CSM mass that could be devoted to cameras, film, sensors, tape, and life support. On the other hand, the DPS would remain available as a backup or supplement to the SPS at least through LOI and, in almost all cases, for several days thereafter.

The SAA Program evolved rapidly, and the many changes it underwent have never been fully documented. Conrad's proposal appears, however, not to have exerted much influence on SAA planners.

More consequential by far was the Apollo 1 fire (January 27, 1967), which undermined support in Congress for NASA and, along with LM development difficulties, delayed the first manned lunar landing until July 1969. All six manned moon landings took place within the Apollo Program, and no Apollo lunar polar orbit mission or surface stay longer than about three days occurred.

The Saturn V rocket designated AS-511 in Conrad's memo launched Apollo 16 in April 1972. By then, NASA had changed its designation to SA-511. The SA-512 Saturn V launched Apollo 17, the final lunar landing mission, in December 1972, and SA-513 launched the Skylab Orbital Workshop, the sole surviving remnant of the SAA Program, in May 1973 (image below).

Combining Lunar Polar Orbit Mission with and Unmanned Landing, Case 218, P. W. Conrad, Bellcomm, In.c, April 4, 1966.

http://beyondapollo.blogspot.com/2011/06/modap-1963.html

http://beyondapollo.blogspot.com/2011/11/saturn-apollo-applications-summary-1966.html

http://beyondapollo.blogspot.com/2009/11/early-aap-mission-plan-1966.html

Saturn-Apollo Applications Summary (1966)

2011-11-17T13:56:00.000-08:00

In early 1964, President Lyndon Baines Johnson called on NASA to declare its plans for U.S. spaceflight after Apollo reached the moon. In response to his request, NASA Administrator James Webb formed the internal ad hoc Future Programs Task Group. The Group sent Webb a report in January 1965 that favored a post-Apollo program based on Apollo hardware; specifically, Command and Service Module (CSM) and Lunar Module (LM) spacecraft and Saturn IB (bottom two images above) and Saturn V rockets.

Responding to the Task Group's recommendation, NASA established the Saturn-Apollo Applications (SAA) Program Office in August 1965. A month later, the SAA Program officially absorbed Apollo Extension Systems (also called Apollo Systems Extension) planning begun more than a year earlier (see link below). Ten months after that, in a June 1966 memorandum, the NASA Headquarters SAA Program Office described an SAA Program which it said was designed to "continue without hiatus an active and productive post Apollo Program of manned space flight and to exploit for useful purposes. . .the capabilities of the Saturn Apollo System." The memorandum explained that the plan it described was based on proposals that the space agency had submitted to President Johnson's Bureau of the Budget only a month earlier, in May 1966.

SAA Program objectives would fall into two basic areas, the memorandum explained. Long-Duration Flights would "measure the effects on men and on manned systems of space flights of increasing duration. . . [and] acquire operational experience with increasingly longer manned space flights" in order to "establish the basic capabilities required for any of the projected next generation of manned space flight goals (earth orbital space station, lunar station, or manned planetary exploration)." The second area, Spaceflight Experiments, would emphasize life sciences, astronomy/space physics, advanced lunar exploration, and space technology applications and development. SAA lunar exploration would, the memorandum explained, support objectives proposed at the July 1965 meeting of space and lunar scientists in Falmouth, Massachusetts.

At the time that the SAA Program Office prepared its memo, the first Apollo lunar landing attempt was expected in late 1967 or early 1968. NASA had ordered from its contractors 21 CSMs, 15 LMs, 12 Saturn IBs, and 15 Saturn Vs for delivery between 1966 and 1970. The memorandum assumed that four Saturn IBs (designated AS-209 through AS-212), six Saturn Vs (AS-510 through AS-515), and their associated CSM and LM spacecraft would remain unused after the first successful moon landing, and that these would immediately become available for SAA missions. Basic Apollo CSM and LM spacecraft would be quickly modified to achieve new goals by the installation of "overlay kits."

Building on these assumptions, the memorandum described two possible SAA Program schedules. The Case I SAA schedule assumed that no Saturn-Apollo hardware beyond that ordered for the moon program would become available before late 1968 and that only enough missions would be flown to accomplish minimal SAA goals. Case I would see 21 Saturn IB and 16 Saturn V launches.

The more ambitious Case II schedule would see "an early extensive utilization of Saturn Apollo capabilities, with an earlier focus on a post-Apollo national space objective (such as a prototype of a space station or a planetary mission module)." Case II, which would include 26 Saturn IB and 17 Saturn V launches, would begin in 1968 with the AS-209, AS-210, AS-211, and AS-212 missions.

AS-209 and AS-210, 14-day Earth-orbital life sciences/crew training missions launched on Saturn IB rockets, would kick off the Case II SAA Program. Their CSMs would dock for crew transfer and an orbital rescue test.

AS-211 would see the launch of the first spent-stage "Workshop" of the SAA Program. The crew would detach their CSM from the Saturn IB S-IVB second stage that inserted it into Earth orbit, then would turn and dock with a Spent Stage Experiment Support Module (SSESM) mounted on the front of the stage (top two images above). In addition to docking ports, the SSESM would provide gaseous oxygen for purging and filling the S-IVB's 20-foot-diameter hydrogen tank so that it could serve as a habitable volume, solar panels for making electricity, an airlock for spacewalks, and experiment equipment. The astronauts would conduct biomedical and astronomy/space physics experiments on board the CSM and the spent-stage Workshop for from 28 to 56 days.

The AS-212 astronauts would deliver fresh supplies to the AS-211 spent-stage Workshop. They would then rendezvous with the Pegasus 3 satellite launched on July 30, 1965, so that they could spacewalk to retrieve meteoroid-capture and thermal coating test panels.

The first of four SAA missions of 1969, AS-213, would be a near-duplicate of the AS-211 mission. On AS-214, a CSM and the first LM-based Apollo Telescope Mount (ATM) would carry out a 14-day solar astronomy mission. SAA flights in 1968-1970 would occur during solar maximum, so in general their astronomy programs would emphasize the Sun. The AS-214 CSM would also dock with the AS-213 spent-stage Workshop to provide resupply and crew rotation. AS-215, a meteorology-oriented mission dubbed "Applications-A," would possibly operate in a high-inclination Earth orbit and employ an experiment/sensor carrier based on the Apollo LM.

Before 1966 was out, the SAA Program would include in its planning ATM and other LEM-based lab & carrier dockings with spent-stage Workshops. These would form multi-modular space stations. In June 1966, however, the SAA ATMs, labs, and carriers were assumed to operate apart from the Workshops while docked with a piloted CSM.

The AS-510 mission, the first mission of the SAA Program to be launched on a Saturn V, would place a CSM into geosynchronous Earth orbit (GEO) for communications, biomedicine, and Earth observation experiments. The rocket's S-IVB third stage, only lightly modified for the mission, would ignite in low-Earth orbit to boost the CSM into an elliptical transfer orbit, then would fire again 5.5 hours later to circularize its orbit at the GEO altitude of 35,870 kilometers.

Five SAA Program Saturn IB missions would fly in 1970. These would include a 135-day stay on board a spent-stage Workshop in Earth orbit, two resupply visits to the spent stage Workshop, two solar ATM flights, a Biomed Lab mission, a fluids lab for studying weightless propellant behavior, the Applications-B Earth resource observation mission, and the introduction of an "Extended Capability CSM" capable of independent 45-day flights.

Extended Capability CSM modifications would include long-life, high-capacity fuel cells for making electricity and water, an oxygen-nitrogen breathing mixture to replace Apollo's pure oxygen atmosphere (this would be a concession to space physicians, who were concerned about the health effects of breathing pure oxygen for long periods), and a long-life C-1 rocket engine in place of the CSM Service Propulsion System main engine. The Biomed Lab would be based on the Apollo LM or a "refurbished Command Module" (a used Command Module converted into a small pressurized laboratory and launched a second time).

Four SAA Saturn V missions would fly in 1970. The AS-511 Saturn V would launch a mapping mission to lunar polar orbit. The AS-512 CSM would transport to lunar orbit an LM Shelter containing living quarters, supplies, and exploration gear (a small rover, a core drill, and an advanced sensor package). Once in orbit over the moon, the LM Shelter would undock from the CSM and land unmanned, then the CSM would return to Earth. Less than three months later, the AS-513 Saturn V would launch an Extended Capability CSM and an LM Taxi to the moon. The latter would land near the LM Shelter with two astronauts on board, including the first scientist-astronaut. They would explore their landing site for 14 days.

The year would end with the unmanned AS-514 launch, which would place the first modified ("Mod") S-IVB Workshop into Earth orbit. Mod S-IVB was a step up from a spent stage; it would launch with no propellants in its tanks and with its hydrogen tank outfitted with living quarters, supplies, and experiment gear.

The four Saturn IB-launched SAA missions of 1971 would, the memo explained, support a one-year stay by a single crew on board the AS-514 Mod S-IVB Workshop. The AS-515 Saturn V would launch an Extended Capability CSM and an ATM on a 45-day mission to GEO to conduct solar astronomy, relativity, and space physics experiments. AS-516 (the first Saturn V built specifically for the SAA Program) and AS-517 would launch an advanced lunar exploration mission similar to the AS-512/AS-513 pair, and AS-518 would launch a second unmanned Mod S-IVB Workshop.

The four Saturn IBs launched in 1972 (AS-225 through AS-228) would support stays on the second Mod S-IVB station. One of these missions would test Command Module modifications meant to replace Apollo ocean landings with cheaper land landings. Modifications would include steerable parachutes.

From 1972 through 1975, the memo explained, SAA missions would support a transition to an unspecified post-SAA manned "follow-on program." The space agency would increase its Saturn IB launch rate to six per year by 1973, and would continue to launch Saturn V rockets at a rate of four per year. The latter would launch four missions to GEO to conduct stellar astronomy, physics, and technology applications experiments (1972-1973), the automated Voyager Mars probes (1973), and a two-launch advanced lunar mission similar to the AS-512/AS-513 and AS-516/AS-517 pairs each year through 1975. Two of the GEO missions would include ATMs. AS-520 and AS-521 would launch the 1972 lunar mission pair and AS-525/AS-526 would launch the 1973 pair.

NASA began the SAA Program amid increasing government fiscal pressures brought on mainly by the cost of the escalating war in Indochina. NASA's annual budget peaked at $5.25 billion in Fiscal Year (FY) 1965. It declined to $5.18 billion in FY 1966. President Johnson submitted a $5.01 billion budget for FY 1967, of which Congress eventually appropriated $4.97 billion. Congress had slashed to $83 million the $270 million that the Johnson White House had requested for the Apollo Applications Program (AAP), as the SAA Program had by then become known.

By that time, the cost of the Vietnam War had soared to $25 billion per year (a hefty sum in the 1960s). Nevertheless, for FY 1968 Johnson requested that NASA's budget be increased to $5.1 billion, of which $455 million would be spent on AAP. The Apollo 1 fire (January 27, 1967) and ill-timed efforts to secure new-start funding for a piloted Mars flyby mission in 1975 induced Congress to cut the agency's FY 1968 appropriation to $4.59 billion, with AAP receiving only $122 million.

Under President Richard Nixon, NASA's budget slide accelerated. He permanently shut down the Saturn rocket production lines (January 1970), approved the Space Shuttle with inadequate funding support (January 1972), and indefinitely deferred a permanent Earth-orbiting Space Station and manned Mars missions. Work toward using Saturn-Apollo hardware in post-Apollo missions continued, however.

Apollo 17 (December 1972) was the last manned mission to the moon. NASA designated its Saturn V as SA-512. On May 14, 1973, SA-513, the last Saturn V to fly, launched Skylab, an S-IVB-based Orbital Workshop (OWS) resembling the SAA Program's Mod S-IVB Workshop. An ATM for solar studies, the design of which was not based on the LM, reached orbit permanently attached to the OWS, and the SSESM had been relabeled the Multiple Docking Adapter. Three Saturn IBs (SA-206 through SA-208) launched three-man crews to Skylab in Apollo CSMs. The final Skylab crew splashed down on February 8, 1974, after 84 days in space.

The SA-210 Saturn IB, the last Saturn rocket to fly, launched the last Apollo CSM to fly. Its July 1975 mission to dock with a Soviet spacecraft in low-Earth orbit brought the Apollo era to a close.

A second Skylab OWS, two complete Saturn V rockets (SA-514 and SA-515), and one complete Saturn IB rocket (SA-211) remained earthbound. The U.S. manned spaceflight endurance record set on the last Skylab mission remained unchallenged until astronaut Norman Thagard lived on board the Russian Mir space station for 115 days in 1995.

"Saturn/Apollo Applications Program Summary Description," memorandum with attachments, MLD/Deputy Director (Steven S. Levenson for John H. Disher), Saturn/Apollo Applications, NASA Headquarters, to George M. Low, Manned Spacecraft Center, Leland F. Belew, Marshall Space Flight Center, and Robert C. Hock, John F. Kennedy Space Center, June 13, 1966.

http://beyondapollo.blogspot.com/2010/02/ase-and-apollo-x-1964.html

Gemini Extravehicular Planning Group (1965)

2011-11-08T17:37:00.001-08:00

At 0700 UTC on March 18, 1965, the Soviet Union's Voskhod 2 spacecraft lifted off from Baikonur Cosmodrome in Soviet Central Asia bearing rookie cosmonauts Pavel Belyayev and Alexei Leonov. As soon as Voskhod 2 entered a 167-by-475-kilometer orbit inclined 64.8° relative to Earth's equator, Belyayev assisted Leonov with preparations for the mission's main objective: to accomplish history's first-ever spacewalk.

The 5682-kilogram spacecraft carried a 1.2-meter-diameter inflatable airlock called Volga mounted over the inward-opening crew hatch of its 2.3-meter-diameter spherical reentry module. The airlock was necessary because Voskhod 2's electronics were air-cooled, so would overheat if its cramped cabin were depressurized. Following inflation - a process that lasted seven minutes - Volga extended 2.5 meters out from Voskhod 2's silvery hull.

Steps in Leonov's spacewalk: 1 - inflate Volga airlock; 2 - pressurize Volga, don backpack; 3 - open Voskhod 2 hatch, enter Volga; 4 - close Voskhod 2 hatch, attach tether, depressurize Volga; 5 - open Volga hatch, begin egress; 6 - spacewalk; 7 - enter Volga feet first; 8 - close Volga hatch, pressurize Volga; 9 - detach tether, remove backpack, open Voskhod 2 hatch, enter Voskhod 2; 10 - close Voskhod 2 hatch; not shown - fire explosive bolts to discard Volga.

Technicians place Volga airlock over Voskhod 2 crew hatch.

Voskhod 2 spacecraft atop drum-shaped orbit insertion rocket stage.

At 0828 UTC, as the spacecraft neared the end of its first orbit, Leonov entered Volga and Belyayev sealed the Voskhod 2 hatch behind him. Belyayev then depressurized Volga, and Leonov opened its 65-centimeter-wide inward-opening outer hatch. At 0834 UTC, over northern Africa, the 30-year-old cosmonaut pulled himself through the hatch, kicked off the hatch rim, and floated away until he reached the end of his 5.35-meter-long safety tether and rebounded (top image above).

Leonov wore a white backpack containing enough oxygen for 45 minutes outside Voskhod 2. The oxygen entered his white Berkut space suit - a modified Vostok SK-1 intravehicular suit - then vented into space, carrying away exhaled carbon dioxide, heat, and moisture.

History's first spacewalker experimented with positioning himself using his tether, reporting after his flight that it gave him tight control over his movements. Then, at 0847 UTC, over Siberia, Leonov reentered Volga and closed the outer hatch behind him. Belyayev repressurized the airlock and opened the Voskhod 2 hatch so that Leonov could remove his backpack and return to his couch.

After the cosmonauts resealed the hatch, Belyayev fired explosive bolts that separated Volga from Voskhod 2. The spacecraft landed in the Soviet Union on March 19 after 17 Earth orbits. The Soviets declared that world's first spacewalk had been "easy."

NASA took notice. The U.S. civilian space agency had planned its first extravehicular activity (EVA) for Gemini IV, the second of 10 planned piloted Gemini missions. The Gemini IV EVA astronaut would not leave his spacecraft; instead, he would open his hatch (each Gemini astronaut had one) and stand up in the cockpit. This would test the G4C EVA suit and the life-support umbilical linking it to the Gemini spacecraft's life support system. The first full-exit EVA would take place on Gemini V, then EVAs would become progressively more complex with each new mission. After Leonov's easy spacewalk, however, NASA decided that Gemini IV spacewalker Ed White should try to out-do his Soviet predecessor.

Gemini spacecraft.
Gemini IV's two-stage Titan II launch vehicle boosted it into a 283-by-161-kilometer, 94-minute orbit on June 3, 1965. Gemini IV separated from the Titan II second stage, then command pilot James McDivitt sought to rendezvous with it. The flight plan called for him to pilot Gemini IV to within seven meters of the stage during the mission's first orbit. Near the end of the second orbit, about three hours after launch, White would leave the cockpit and, using a Hand-Held Maneuvering Unit (HHMU), attempt to reach the spent stage.

Unfortunately, rendezvous proved to be more difficult than anticipated. The spent stage vented propellants, causing it to tumble. This subjected it to increased atmospheric drag, causing it to move away from Gemini IV. McDivitt set out in pursuit, but found his efforts thwarted by poor visibility, inability to accurately judge distance (Gemini IV included no rendezvous radar), and an incomplete grasp of orbital mechanics. With Gemini IV's propellant supply dwindling, McDivitt called off the rendezvous.

EVA preparation needed more time than expected, then White's hatch refused to unlatch, so the first U.S. EVA did not begin until Gemini IV's third orbit. After shoving back the stiff hatch, White pushed out of the cockpit (bottom image above). He successfully tested the HHMU, which contained only enough compressed oxygen propellant for 20 seconds of maneuvering.

White then evaluated his umbilical. He found it to be useful for controlling his distance from Gemini IV and for pulling himself back to the spacecraft, but he was unable to demonstrate the precision maneuvering Leonov had reported. At one point, in fact, he accidentally collided with and smeared McDivitt's cockpit window.

White's life-support umbilical was covered in a thin layer of gold to protect it from the fierce sunlight of low-Earth orbit. If the umbilical had for any reason ceased to supply him with oxygen, his chest-mounted Ventilation Control Module (VCM) could have supplied him with enough to return safely to his seat. Much as with Leonov's Berkut, oxygen passing through White's 10.7-kilogram G4C suit flushed exhaled carbon dioxide, heat, and moisture into space. America's first spacewalker reported later that he was more comfortable during his EVA than at any other time during the Gemini IV flight.

With Gemini IV moving rapidly toward night, White reluctantly returned to the cockpit. There he found that internal pressure had caused his suit to balloon slightly. During the five-minute struggle to squeeze back into his narrow seat and close his balky hatch, heat from White's exertions overcame the G4C's cooling capacity. His visor fogged slightly and sweat blinded him until he could remove his helmet in the repressurized cockpit and wipe his eyes.

NASA judged White's 20-minute EVA to have been a resounding success. EVA, it seemed, presented few challenges. NASA management was, on the other hand, alarmed by McDivitt's inability to rendezvous with the Titan II second stage. Rendezvous was a critical part of NASA's Lunar Orbit Rendezvous plan for landing a man on the moon by 1970. By the end of June, NASA top brass were considering cancelling the progressively more challenging EVAs scheduled for Gemini missions V, VI, and VII so that engineers, flight controllers, and astronauts could concentrate on rendezvous.

In July 1965, NASA made decisions critical to Gemini EVA planning. On July 2, the Gemini Program Office (GPO) at the Manned Spacecraft Center (MSC) in Houston, Texas, formed the Gemini Extravehicular Planning Group (GEPG) to revise EVA objectives for Gemini missions VIII, IX, X, XI, and XII. On July 12, NASA Headquarters directed the GPO to postpone the next U.S. spacewalk until Gemini VIII. The GEPG submitted its recommendations to Gemini Program Manager Charles Mathews on July 19.

The GEPG based its recommendations on several assumptions. First, of course, was that the EVA objectives planned for Gemini VIII would be attainable without the gradual development of skills that would have occurred during the Gemini V, VI, and VII EVAs.

In addition, the GEPG assumed that NASA would beat the rendezvous and docking problem. Gemini missions VIII through XII would each include a docking with a Gemini Agena Target Vehicle (GATV), an Agena-D upper stage modified to serve as a Gemini docking target and auxiliary propulsion stage. The GATV, launched on an Atlas rocket, would include a latch-equipped docking adapter sized to accept the Gemini spacecraft's blunt nose. During the Gemini VIII, IX, X, XI, and XII EVAs, the Gemini would remain docked to the GATV.

Gemini Agena Target Vehicle.
The GEPG noted that oxygen flow through White's space suit had kept him cool and dry "except when [he] was working at a high exertion level." On Gemini VIII and subsequent missions, an Extravehicular Life Support System (ELSS) would replace the VCM. The ELSS could be used with a backpack-mounted oxygen supply that would permit hour-long EVAs without an umbilical. The GEPG recommended that the Gemini VIII EVA astronaut test the ELSS chest-pack to ensure that it could cool even a hard-working spacewalker adequately.

The GEPG also recommended that EVA equipment too large for cockpit storage be stowed on the aft-facing concave surface of the Adapter Section, the aft-most and widest part of the Gemini spacecraft, as well as on the GATV. On Gemini VIII, oversize equipment would include an HHMU with 10 times as much compressed oxygen as White's HHMU. The Gemini VIII EVA astronaut would evaluate the Adapter Section stowage concept, then test the HHMU.

Before returning to the cockpit, he would also "inspect the Agena for engineering analysis," test a space hand tool, and evaluate a lightweight safety tether and a backup "suit exhaust" EVA propulsion system. By clambering over the two spacecraft, he would evaluate transfer between two vehicles, a skill of potential use in the Apollo Program if astronauts found themselves compelled in the event of docking problems to move by EVA between the Apollo Command and Service Module (CSM) and Lunar Module (LM). The many EVA tasks planned for Gemini VIII through XII would require EVAs of greater duration than White's, so the Gemini VIII spacewalker would also evaluate EVA operations during orbital night, which would last for about half of each orbit.

Modular Maneuvering Unit (later called Astronaut Maneuvering Unit) and modified Gemini G4C space suit.
Gemini IX would see the first use of the U.S. Air Force Modular Maneuvering Unit (MMU), a hydrogen-peroxide-fueled "rocket pack" that would reach orbit stowed in the Adapter Section. The Gemini IX EVA astronaut would back up to the MMU, connect his ELSS to its integral oxygen supply, then grip t-shaped hand controllers and fly away from Gemini IX. The MMU's hot-gas thrusters would require that the astronaut's G4C suit be modified to include protective multilayer metal-fabric and foil leg coverings.

The GEPG noted that MMU development was proceeding to schedule, but added that NASA and the Air Force had yet to agree on the MMU's purpose or on whether it could fly without a safety tether linking it to the Gemini spacecraft. These questions were, it added, "beyond the scope of the present planning study."

The Gemini X EVA astronaut's tasks would focus on his spacecraft and the space environment. He would release "dense smoke" ahead of Gemini X and film its flow over the spacecraft's surfaces, photograph Gemini thrusters firing during day and night, gauge static charge on Gemini X and its GATV using a hand-held electroscope, measure hull temperature, and collect samples of contaminants (for example, the greasy contaminant that tended to cloud Gemini cockpit windows).

The GEPG also recommended two tether dynamics experiments for Gemini X. The spacewalker would simulate an untethered EVA using a "long slack tether," then would link his spacecraft and an inoperative Agena using a "towline." After the EVA, Gemini X would attempt to pull the Agena through space in an "evaluation of dynamics of orbital tow."

Gemini XI would see a dramatic increase in EVA complexity. The spacecraft would intercept the 10.5-ton Pegasus 3 satellite, which was due to be launched into low-Earth orbit on a Saturn I rocket soon after the GEPG submitted its report. Like its predecessors, Pegasus 3 was designed to assess the likelihood that spacecraft in low-Earth orbit would suffer meteoroid impact damage. To do this, it unfolded a pair of 4.3-meter-wide-by-29-meter-long "wings" containing a total of 400 meteoroid-detection panels.

Pegasus meteoroid detection spacecraft.
The GEPG reported that discussions with NASA Headquarters and NASA Marshall Space Flight Center had already led to Pegasus 3 modifications. Pegasus 1, launched February 16, 1965, had achieved an elliptical 510-by-726-kilometer orbit, while Pegasus 2, launched May 25, 1965, had entered a 502-by-740-kilometer orbit. When launched on July 30, 1965, Pegasus 3 entered a near-circular 535-by-567-kilometer orbit. This made it an easier rendezvous target.

In addition, 16 of Pegasus 3's meteoroid-detection panels had been replaced with removable aluminum meteoroid-capture panels and panels containing thermal control test surfaces. After rendezvous with the giant satellite, the Gemini XI spacewalker would use an HHMU to jet over and remove the panels for return to Earth. The GEPG stated that "[d]etermination of the method of accomplishing this task. . .must still be accomplished."

Gemini XII would see the second flight of the MMU rocket pack. If the Gemini IX MMU test was performed using a tether, then consideration would be given to untethered flight during Gemini XII. The mission would also rendezvous with the 2300-kilogram Missile Defense Alarm System (MIDAS) II satellite, which had been launched on May 24, 1960, and failed two days later. The EVA astronaut would inspect and photograph MIDAS II in an effort to determine the cause of its failure.

The GEPG suggested alternate missions for Gemini XI and XII that would see one or both meet up with Apollo spacecraft in orbit. A Gemini might, for example, rendezvous with the SA-204 Apollo CSM, which in July 1965 was scheduled to be launched in September 1966. SA-204 was planned to be the first manned Apollo CSM flight, but it would be flown unmanned if either of the two suborbital test flights scheduled to precede it failed. The EVA astronaut would transfer to and enter the unmanned CSM, check out its systems, and return to the Gemini.

If Gemini XII were postponed until February 1967, then it could rendezvous with the unmanned LM planned for launch on mission SA-206. The spacewalker would enter the spindly LM, check out its systems, and jet back to Gemini XII.

NASA accepted many of the GEPG's recommendations. As it began to implement them, it conducted Gemini missions V, VI, and VII. After a rough start, Gemini V (Gordon Cooper and Charles Conrad, August 21-29, 1965) successfully conducted an improvised "phantom rendezvous" with a point in space and remained in orbit for eight days. Gemini VII (Frank Borman and James Lovell, December 4-18, 1965) stayed aloft for 14 days, demonstrating that astronauts could survive in space for long enough to reach and return from the moon.

Gemini VI (Wally Schirra and Tom Stafford, December 15-16, 1965) had been scheduled to launch on October 25, 1965, but NASA postponed the mission after its GATV was destroyed during ascent to orbit. The agency decided that Gemini VI should instead pay a visit to the long-duration Gemini VII crew. On December 12, the Gemini VI Titan II booster ignited, then shut down before it could rise off its launch pad. Command Pilot Schirra opted not to trigger a perilous pad abort, saving the mission. On December 15, Gemini VI at last lifted off and performed rendezvous and proximity operations with Gemini VII. As 1965 ended, NASA looked ahead to dockings and spacewalks in 1966.

Gemini VII as viewed from Gemini VI. Note the concave gold foil-covered aft surface of the Adapter Section, where the AMU and other EVA equipment too large for the Gemini cockpit could be carried.
Gemini VIII (Neil Armstrong and David Scott, March 16-17, 1966) became the first manned spacecraft to perform a docking - and the first Gemini mission with a successful GATV - but then suffered a thruster malfunction that sent the docked vehicles spinning out of control. The astronauts made an emergency landing, so Scott was unable to perform the first spacewalk since Gemini IV.

Despite this, NASA proceeded with Gemini IX (Tom Stafford and Eugene Cernan, June 1-11, 1966) as if the Gemini VIII EVA had succeeded. Cernan, the agency announced, would move to the aft end of the Gemini IX Adapter Section, don the Astronaut Maneuvering Unit (AMU) - as the MMU had been renamed - and fly up to 45 meters from the spacecraft.

Cernan's spacewalk was a near-disaster. He quickly overheated, fogging his faceplate. He found that handholds, loop-shaped foot restraints, and velcro patches on Gemini IX's exterior gave him scant help in controlling his movements. He estimated after the flight that 50% of his energy had been devoted to fighting the internal pressure of his modified G4C suit so that he could hold position. Nearly blinded by sweat, he tore his suit's outer thermal layers as he moved over Gemini's IX's hull. Through heroic efforts, and with his pulse racing at 195 beats per minute, he managed to reach and don the AMU before Stafford ordered him back to the cockpit.

NASA began to revise its ambitious EVA plans. Gemini X (John Young and Michael Collins, July 18-21, 1966) started with a low-key EVA during which Collins performed astronomical ultraviolet photography while standing in the cockpit. During his second EVA, which began just 90 minutes after the first, he used an HHMU to move to the derelict Gemini VIII GATV. His clumsy movements caused the GATV to gyrate, making it difficult for Young to keep Gemini X close by. Young called off the EVA, which was to have lasted 90 minutes, just 39 minutes after Collins left the cockpit.

Gemini XI (Charles Conrad and Richard Gordon, September 12-15, 1966) was, if anything, even worse. Gordon quickly overheated as he fought to attach a tether to the Gemini XI GATV without adequate handholds. Conrad called off the scheduled 107-minute spacewalk after 38 minutes. In his post-flight debrief, Gordon reported that "a little simple task that I had done many times in training to the tune of about 30 seconds lasted about 30 minutes."

No Gemini performed a rendezvous with Pegasus 3. The meteoroid and thermal control test surface panels that the GEPG had hoped a spacewalker would recover during Gemini XI were destroyed when the satellite reentered Earth's atmosphere on August 4, 1969.

NASA kept the AMU on the manifest of Gemini XII (James Lovell and Edwin Aldrin, November 11-15, 1966), going so far as to install it on the spacecraft on September 17, 1966. On September 23, however, as the significance of Gordon's EVA troubles hit home, NASA Headquarters ordered the rocket pack removed.

Desperate for a successful EVA, the agency revised Aldrin's training regimen and EVA plan. His three EVAs had a relaxed pace and were spread out over three days. He had at his disposal a variety of new handholds, footholds, and other restraint devices. NASA also limited his EVAs to relatively simple tasks, such as testing space tools while firmly restrained.

The Soviet Union and Alexei Leonov maintained the fiction that his historic spacewalk had been easy until the late 1980s. After the fall of the Soviet Union in 1991, it was revealed that Leonov's Berkut suit had ballooned in the vacuum of space. He was unable to reach a camera switch on his thigh, so could not photograph Voskhod 2 as planned.

After about 10 minutes outside, Leonov began his return to Voskhod 2. He entered Volga head first (not feet first, as planned), so had to turn in the airlock to shut its hatch behind him. After becoming trapped sideways in the fabric airlock, he flirted with dysbarism ("the bends") by lowering his suit's internal pressure so that he could free himself and seal the hatch. His exertions overwhelmed Berkut's air-flow cooling system, causing his core body temperature to rise 1.8° Celsius in 20 minutes.

Leonov's EVA would be the last Soviet spacewalk until the Soyuz 4-Soyuz 5 docking mission of January 14-18, 1969. By the time Yevgeni Khrunov and Alexei Yeliseyev performed history's first two-person EVA on January 16, 1969, Soviet space suit designers and EVA planners had had time to benefit from NASA's Gemini EVA experience. Khrunov and Yeliseyev wore Yastreb space suits with cable-and-pulley systems and metal parts to prevent ballooning and improve mobility. Their 37-minute external transfer from Soyuz 5 to Soyuz 4 took place without significant incident.

Memorandum with attachment, GS/Chairman, Gemini Extravehicular Planning Group, to Manager, Gemini Program, Report of Gemini Extravehicular Planning Study, July 19, 1965.

"The First Egress of Man into Space," A. A. Leonov; paper presented at the 16th International Astronautics Congress in Athens, Greece, September 13-18, 1965.

Walking to Olympus: An EVA Chronology, Monographs in Aerospace History Series #7, David S. F. Portree and Robert C. Trevino, NASA History Office, October 1997 (http://history.nasa.gov/monograph7.pdf) (accessed 11/2/11).

McDonnell Douglas Phase B 12-Man Space Station (1970)

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In the autumn of 1966, NASA asked President Lyndon Johnson's Bureau of the Budget (BOB) for $100 million in Fiscal Year (FY) 1968 to begin Phase B contractor studies of Earth-orbital space stations. With the Apollo Program's culmination drawing near, the U.S. civilian space agency was eager to establish post-Apollo goals, and topping its wish-list was a space station - an Earth-orbiting laboratory for testing the effects on men and machines of long-term exposure to space conditions and for performing scientific and technological experiments and Earth and space observations.

NASA had performed internal Phase A space station studies almost since it opened its doors in October 1958. If NASA had had its way, a space station would have preceded Apollo's reach for the moon. President John F. Kennedy's May 1961 call for a man on the moon ahead of the Russians and before the end of the 1960s had, however, preempted space station development. The FY 1968 funding request was in some sense a plea to restore NASA's program to the traditional space station/moon/Mars progression described in Wernher von Braun's 1950s blueprint for spaceflight.

The BOB turned down NASA's request; then, in January 1967, the Apollo 1 fire profoundly altered the U.S. space policy environment. NASA came under increased scrutiny and funding for post-Apollo space goals became even more restricted. Congress dealt the only approved post-Apollo manned program - the Apollo Applications Program (AAP), which would reapply Apollo lunar mission hardware to new goals, including a series of Earth-orbiting laboratories based on spent S-IVB rocket stages - a half-billion-dollar funding cut in August 1967.

NASA recovered from the fire - in November 1967, the successful first flight test of the three-stage Saturn V moon rocket did much to restore confidence - but funding for post-Apollo programs was still not forthcoming. When NASA Administrator James Webb, who had led the agency from Apollo's beginning, announced in September 1968 that he would step down, he told journalists that NASA was "well prepared. . .to carry out the missions that have been approved." He added, however, that "[w]hat we have not been able to do under the pressures on the budget has been to fund new missions. . ."

Webb's deputy, Thomas Paine, became Acting NASA Administrator (middle image above). Webb, whose earliest Federal government experience dated to 1932, had deftly piloted NASA through Washington's political shoals; Paine, by contrast, had just seven months of experience in government service. Paine displayed his inexperience almost immediately by pressing President Johnson for a space station decision in the final weeks of his Administration. Johnson deferred the decision to the next President.

Soon after President Richard M. Nixon's January 1969 inauguration, Paine made another Space Station pitch. He apparently hoped that Apollo Program successes would induce the new President to give NASA a blank check for future projects. Though the Apollo 8 Command and Service Module (CSM) had triumphantly orbited the moon and returned its three-man crew safely to Earth less than a month before his inauguration, Nixon refused to commit to new NASA programs. Instead, he postponed any decision on NASA's future direction at least until after the newly appointed Space Task Group (STG) completed its report in September 1969. Paine was a voting member of the STG, which was chaired by Vice-President Spiro Agnew.

Paine chose not to await the outcome of the STG's deliberations. In January-February 1969, he oversaw creation within NASA of a Space Station Task Force, a Space Station Steering Group, and an independent Space Station Review Group. These bodies prepared a Phase B Space Station Study Statement of Work (SOW), which NASA released to industry on April 19, 1969.

The SOW solicited proposals to study a 12-man Space Station, the design of which could eventually serve as a building block for a 100-man Earth-orbital Space Base. The 12-man Space Station was to reach orbit on a Saturn V rocket in 1975 and remain in operation for 10 years. Sixty percent of Phase B study effort was to be devoted to the 12-man Space Station, 15% to its future role as part of the Space Base, 15% to an interim logistics spacecraft for delivering early crews and supplies to the 12-man Space Station, and 10% to 12-man Space Station interfaces with an advanced logistics system (namely, a reusable Space Shuttle).

Grumman, North American Rockwell (NAR), and McDonnell Douglas Astronautics Company (MDAC) submitted proposals. On July 22, 1969 - two days after the successful Apollo 11 moon landing - NASA awarded to NAR and MDAC Phase B Space Station study contracts worth $2.9 million each. This was a far cry from the $100 million Webb had sought in late 1966 to fund Phase B studies.

Phase B study work began formally in September 1969, though the contractors had begun to put together industry teams and spend their own money on the study even before NASA issued its SOW. The MDAC and NAR teams each included more than 30 subcontractors. NAR and MDAC were eager to move forward at their own expense because they expected that the eventual Phase C/D Space Station development contract would be extremely lucrative.

NASA's Manned Spacecraft Center (MSC) in Houston managed the NAR Phase B study, while Marshall Space Flight Center (MSFC) in Huntsville, Alabama, managed MDAC's work. This division of labor reflected pre-existing NASA center/contractor relationships. MSC managed NAR's contract to build the Apollo CSM, while MDAC was prime contractor for MSFC's S-IVB-based AAP Orbital Workshop (bottom image above). The AAP Workshop was renamed Skylab in February 1970.

In March 1969, the U.S. Department of State had come out cautiously in favor of NASA's proposed Space Station/Space Shuttle program because it expected that it might open up opportunities for international cooperation. With that in mind, NASA invited foreign representatives to participate in the Phase B study's quarterly reviews. In early June 1970, as the Phase B study neared its planned conclusion, the European Space Research Organization (ESRO) returned the favor by inviting NAR and MDAC to present briefings on their Phase B studies in Paris.

C. J. Dorrenbacher, MDAC's Vice President for Advance Systems and Technology, began his presentation by drawing links between his company's 12-man Space Station design (top image above) and Skylab, which he said was scheduled to launch during 1972. Skylab, he told the Paris meeting, would see NASA manned spaceflight evolve from "cockpit to space ship accommodations." He explained that Skylab would contain "many systems that are prototypes of those to be used on the Space Station," and added that "experience in the operation, maintenance, and habitability of [Skylab] will significantly extend our knowledge and, thus, our confidence in the Space Station Program."

Like Skylab, MDAC's Space Station would leave Earth on a two-stage Saturn V. Designated INT-21, the rocket would comprise S-IC and S-II stages measuring 9.2 meters in diameter. This would define the diameter of MDAC's Space Station. The S-II second stage would inject the bullet-shaped 34-meter-long Station into a 456-kilometer-high circular orbit inclined 55° relative to Earth's equator. Its labors completed, the stage would then detach and deorbit itself over a remote ocean area.

MDAC's Station would comprise two main modules: the two-deck, roughly conical artificial-gravity module at its front and the four-deck, drum-shaped core module. The 15-meter-long core module would be divided into two independent sections, each with a research deck and a living deck, while the artificial-gravity module would include a living deck and a research deck. Each of the three sections would have independent life-support systems and could house the entire crew in an emergency. The artificial-gravity and core modules would also each include an unpressurized equipment compartment.

Soon after reaching orbit, MDAC's Station would discard a streamlined nosecone covering its front docking port. A "telescoping spoke" linking the artifical-gravity and core modules would then extend to separate them by a few meters. This would expose the core module's equipment compartment, enabling four large radio dish antennas to deploy and exposing waste heat radiators for the Station's twin Isotope/Brayton (I/B) nuclear power units. The I/B units, which would each produce 10 kilowatts of electricity, would be designed to eject from the Station in an emergency and safely reenter Earth's atmosphere.

By the time of the Paris briefings, NASA had pushed back the planned launch of the 12-man Space Station to 1977. Though this move was inspired by increasingly disheartening budget projections, space agency officials hoped that the two-year slip would ensure that the Space Shuttle would be ready to deliver astronauts, supplies, equipmemt, and experiment modules to the orbiting Station, eliminating the need for an interim logistics vehicle. For its study, MDAC assumed a fully reusable Shuttle system with a piloted winged Booster and a piloted winged Orbiter with a 4.6-by-18.3-meter cargo bay.

Flight controllers on Earth would remotely check out the Station's vital systems. If it checked out as habitable, then 24 hours after it reached orbit its first 12 residents would lift off from Cape Kennedy. Eight hours later, their Orbiter would rendezvous with the Station and open its cargo bay doors. The crew would depart the cargo bay inside an 18,000-kilogram Crew/Cargo Module (CCM). MDAC's CCM, an Apollo-CSM-sized independent spacecraft, resembled designs for drum-shaped cargo spacecraft and small space station modules based on Gemini spacecraft hardware put forward by McDonnell Aircraft as early as 1962. The company probably viewed the CCM as a way of salvaging its interim logistics vehicle design in a Shuttle-based logistic supply system. Gemini, which carried 10 two-man crews into Earth orbit in 1965-1966, was manufactured by McDonnell before its April 1967 merger with Douglas Aircraft created MDAC.

The CCM would deploy four side-mounted engine modules and maneuver to a docking at the Station's aft port on the core module. The astronauts would then enter the Station and begin checking out its systems. If initial Station manning came off without a hitch, the Orbiter would commence its return to Earth twenty-five hours after the Station crew left its cargo bay.

CCMs would subsequently arrive at MDAC's Station every 90 days with fresh crews and supplies. Of the CCM's mass, about 13,000 kilograms would comprise cargo. After a new CCM docked carrying a new crew, the crew already on board the Station would board their CCM, undock, maneuver to the waiting Orbiter, and enter its cargo bay. The Orbiter would then close its cargo bay doors and return to Earth.

The 1.5-meter hatch through which the first astronauts would enter their new home would open into the core module's central "tunnel." Besides forming the main "artery" linking the core module's four pressurized decks, the three-meter-diameter cylinder would provide emergency living quarters for the entire crew, a passageway for ducts and conduits, radiation-shielded photographic film storage, a 180-day supply of emergency food, and space suit storage.

At the forward end of the core module tunnel, a 1.5-meter hatch would open into a cylindrical airlock. The airlock would occupy the center of the core module's unpressurized equipment compartment. A hatch in the airlock wall would open into the equipment compartment, which would contain liquid and gas tanks, the twin I/B units, their waste heat radiators and power conditioning and distribution subsystems, and unpressurized storage. A 1.5-meter hatch in the airlock ceiling would open into the telescoping spoke leading to the artificial-gravity module.

The telescoping spoke would link to the central tunnel connecting the artificial-gravity module's two decks. A 1.5-meter hatch at the end of the tunnel would open into a cylindrical airlock at the center of the artificial-gravity module's unpressurized equipment module. A hatch in the airlock's side would provide access to unpressurized storage, gas and liquid tanks, and small thrusters and propellant tanks. The equipment compartment would also include a place for the eventual installation of a third I/B power unit. A hatch in the airlock ceiling would connect to the Station's front docking port.

Dorrenbacher told his European audience that the Station's first crew would almost immediately begin a 30-day artificial-gravity experiment. This would entail extending the telescoping spoke to its maximum length. Six crew members would take up residence in the artificial-gravity module, while "some" would occupy a small "zero-gravity cab" inside the spoke at the Station's center of mass and rest the core module.

The astronauts would then ignite the small thrusters in the artificial-gravity module's equipment compartment to set the Station spinning at four rotations per minute about its center of mass. This would produce acceleration which the crew would feel as gravity. On deck 1 of the core module, 19.2 meters from the center of mass, the astronauts would feel acceleration equivalent to 0.35 Earth gravities. On the artificial-gravity module's living deck (deck 6), 39.3 meters from the center of mass, the astronauts would feel 0.7 Earth gravities.

After a month of artificial-gravity experimentation, the astronauts would halt the Station's rotation using the small thrusters, restoring it to a zero-gravity condition. The artificial-gravity module would carry enough propellants to permit up to five similar experiments.

Dorrenbacher described the 12-man Space Station as "a research facility to accommodate all experiment disciplines. . .a general-purpose laboratory." At launch, it would include three experiment decks. Deck 2, dedicated to the study of living things in zero gravity, would include the Station's medical dispensary and isolation ward. Deck 4 would constitute the general purpose laboratory, which would serve both scientific support and engineering roles. It would include a drum-shaped experiment & test isolation facility, a mechanical lab, an electronics/electrical lab, a hard-data processing facility, an optics facility, and a small experiment airlock. Deck 5 would include a pair of centrifuge cabs large enough to accommodate men and experiments.

Based on NASA input, MDAC defined eight experiment disciplines for its Station. These were astronomy, space physics, space biology, Earth survey, aerospace medicine, space manufacturing, engineering/operations, and advanced technology. Not all disciplines could be accommodated simultaneously; for example, the artificial-gravity experiment series would preclude experiments which needed a stable platform and zero gravity.

Dorrenbacher then provided a rough schedule of the Station's experiment programs. Biomedical experimentation would begin with the arrival of the first crew and continue without pause throughout the Station's planned 10-year operational lifetime, as would "man-system integration" experiments. In general, early research not associated with the artificial-gravity experiment series would focus on Station operations and habitability. "Component test" experiments would end in early 1978, "maintenance and logistic" experiments would conclude in late 1978, and "occupancy and space living," "contamination," and "exposure" research would end in mid-1979.

CCMs would deliver new experiment apparatus to replace and augment that launched with the Station, Dorrenbacher told the Paris meeting. Disused experiment hardware and other equipment and furnishings would be packed into CCMs for return to Earth. He suggested that, following the conclusion of the artificial-gravity experiment series in late 1978, furnishings on deck 6 be returned to Earth so that it could be converted into a physics & chemistry laboratory using apparatus delivered by CCMs.

By then, the first Attached Modules (AMs) and Free-Flying Modules (FFMs) would arrive at MDAC's Station in Shuttle Orbiter cargo bays. One AM, devoted to Ultraviolet (UV) Stellar Astronomy, would dock with a port on the core module's side linking it to the deck 4 general-purpose lab. Another AM, devoted to Earth Surveys, would dock either at deck 4's second port or at a port on deck 2. Two FFMs, devoted respectively to Solar Astronomy and High-Energy Stellar Astronomy, would dock with the Station's front port when they needed servicing; for example, after they expended their supplies of photographic film. AMs would rely on the Station for electrical power, while FFMs would each sport a pair of electricity-generating solar array wings.

CCMs, meanwhile, would deliver experiment subjects: in addition to a steady supply of new astronauts, beginning in early 1979 they would transport small vertebrates such as rats and invertebrates such as fruit flies to the Station. Plants would first reach the Station in late 1979.

Also in late 1979, the general Stellar Astronomy FFM would arrive near the Station. MDAC envisioned that UV Stellar Astronomy and High-Energy Stellar Astronomy would conclude at the beginning of 1981, while Solar Astronomy, general Stellar Astronomy, small vertebrate, invertebrate, and plant studies would continue until the Station reached its planned end-of-life in 1987. Biomedical centrifuge and fluid physics AMs would arrive in late 1981, with the former remaining with the Station until end-of-life and the latter departing in late 1985. Small Vertebrates Centrifuge and Infrared Stellar Survey AMs would arrive in late 1982 and remain docked until Station end-of-life.

Late 1983 would see arrival of the Remote Maneuvering Satellite (RMS), which would take up residence in a "hangar" in the airlock linked to the Station's front port. Dorrenbacher called the RMS a "subsatellite," but did not otherwise describe its role. At about the same time, the X-Ray Telescope FFM and advanced particle & plasma physics experiment apparatus would arrive. The X-Ray Telescope FFM would operate through Station end-of-life. Some advanced physics experiments would cease in early 1985, and RMS operations and the remaining advanced physics experiments would cease in late 1986. Late 1985 would see the arrival of materials science experiment apparatus and the Cosmic-Ray Physics FFM, both of which would remain in operation through Station end-of-life.

Dorrenbacher described how the vast quantity of data generated by Station experiments could reach Earth. MDAC estimated that 9070 kilograms of magnetic tape, microfilm, exposed photographic and X-ray film, and photographic plates would need to be returned to Earth each year. The Station's four large dish antennas would enable continuous two-way television communication direct through ground stations or through relay satellites so that Station and Earth researchers could work together continuously in real time. The antennas would be capable of transmitting up to a trillion bits (one terabyte) of data to Earth each day.

The Station's impressive experiment capability would demand careful management of crew time. MDAC assumed that the astronauts would work around the clock, with six men on duty and six men off duty at any one time. Each 12-man crew would include eight scientist/engineers and four Station flight-crew. Four scientist/engineers and two flight-crew would work during each 12-hour shift. One scientist/engineer would serve as principal scientist interfacing with the flight-crew commander, who would have responsibility for the safety of the entire crew. Two scientist/engineers would serve as principal investigator representatives interfacing with scientists on Earth.

Off-duty crewmembers would spend most of their time on the living decks (decks 1, 3, and - during the artificial-gravity experiment - 6). There, Dorrenbacher explained, they would have at their disposal private staterooms with 4.6 meters of floor space for "relaxation, recreation, study, and meditation." Each living deck would include six staterooms, which together would take up about half the deck's floor space. Staterooms would each include a small viewport, a folding bunk, a desk, and storage cabinets.

When not in their staterooms, off-duty crewmembers could hang out in the multi-purpose wardroom, which would include portable dining tables with zero-gravity restraints in place of conventional seats. Dorrenbacher explained that the wardroom could be "quickly and easily" converted into a gym, a theater, a meeting room, or a recreation room.

Cabinets in the galley, adjacent to the wardroom, would be kept stocked with enough food for 90 days. Crewmembers could choose to serve themselves or could take it in turns to prepare meal trays for their colleagues. Dorrenbacher told his audience that meals would be "selected for maximum palatability with various degrees of wet and even fresh foods," but provided few details about how the food would be handled in zero gravity.

The three living decks would each include a hygiene facility. Apparently configured for men only, these would each include a toilet, two urinals, two handwashing units, a shower, a clothes-washing machine, and a clothes dryer. Hygiene facilities would be located next to the water-recycling life-support machinery on each living deck.

MDAC proposed a novel approach to Station orbit maintenance. Some processed waste water would be electrolyzed (split into oxygen and hydrogen using electricity) and the hydrogen used to fuel low-thrust orbit-reboost resistojets on the Station's hull. MDAC calculated that water delivered to the Station in food would be sufficient to maintain its orbital altitude.

MDAC placed the core module control consoles on the living decks adjacent to the wardrooms. The artificial-gravity module would include an identical control console on deck 5. The primary control console - the Station's "bridge" - would be located on deck 3. Consoles on decks 1 and 5 would be considered secondary. They would serve as backups for the deck 3 primary console, and would also support experiments: they might, for example, be used to monitor data arriving from the FFMs.

Dorrenbacher then described an arbitrarily selected moment in the MDAC Station's 10-year career to illustrate possible activities of on-duty and off-duty crewmembers. At 2030 hours Greenwich Mean Time on March 26, 1985, the flight-crew commander would be at work conducting safety checks on space suits on level 3 of the core module tunnel. The shift's other on-duty flight-crew member would, meanwhile, sample the deck 1 water system to ensure that it contained no harmful bacteria.

Two of the scientist/engineers would be at work in the deck 2 labs and two elsewhere. The physician would analyze crew blood and urine samples in the biomedical lab, while the psychologist would analyze data on "crew skill retention in extended zero gravity" in the man/system integration lab. The geologist/photo-optical engineer, meanwhile, would install and align sensors in the Earth Survey AM docked to deck 2, and the astronomer/systems engineer would monitor data from the X-Ray Telescope FFM at the secondary control console on deck 5.

The off-duty crewmembers, having just finished their late meal, would all be found on deck 3. The operations director, a flight-crew member, would take a shower in the hygiene facility, while the physician, a scientist/engineer, would watch a video-taped television program in his stateroom before going to sleep. The other off-duty crewmembers would be in the wardroom. The station controller, a flight-crew member, would compete against the astrophysicist, a scientist/engineer, in a simulated time-distance race on stationary exercise bikes. Nearby, the biologist and the electro-mechanical engineer, both scientist/engineers, would compete at "computer football."

Dorrenbacher concluded his presentation by assuring his audience that MDAC's 12-man Space Station would be a "low-cost, flexible, international research facility" built using known technology (that is, mostly adaptations and upgrades of Skylab hardware). Furthermore, its modules would be readily adaptable to future NASA/ESRO missions: specifically, to serving as building blocks in NASA Administrator Thomas Paine's 100-man Space Base.

As noted earlier, NASA had instructed MDAC to design its 12-man Space Station to be launched on a Saturn V. Dorrenbacher failed to mention to his European hosts, however, that Paine had announced on January 13, 1970, six months before the Paris briefing, that Saturn V production, already on standby, would be permanently ended, and that the last Saturn V, previously assigned to the Apollo 20 moon mission, would be reassigned to launch Skylab. He also neglected to mention that NASA had directed NAR and MDAC in early May to begin considering designs for Space Stations that could be assembled solely from modules launched in the Shuttle Orbiter's cargo bay.

On June 30, 1970, NASA issued Phase B extension contracts to MDAC and NAR. The following month, Paine stepped down as NASA Administrator, and NASA moved rapidly to come into line with the Nixon Administration's developing space policy. That policy gave lukewarm support to the Space Shuttle and left the Space Station it was meant to serve in limbo. Less than two months after the Paris meeting (July 29, 1970), NASA directed MDAC and NAR to study only Shuttle-launched modular stations.

On January 5, 1972, NASA Administrator James Fletcher announced that President Nixon's FY 1973 NASA budget request included modest funds to begin development of a partially reusable Space Shuttle. Though little mention was made of a Space Station, Phase B studies lingered on until late in the year. On November 29, 1972, Fletcher formally abolished NASA's Space Station Task Force and established the Sortie Lab Task Force. The sortie lab was intended to ride in the Shuttle Orbiter's cargo bay, providing an interim Space Station-type research capability during Shuttle missions ("sorties") lasting up to 30 days. In August 1973, NASA and ESRO agreed that the latter should develop the sortie lab, which became known subsequently as Spacelab.

Development and Use of a 12-Man Space Station, MDC G0583, C. Dorrenbacher, McDonnell Douglas Astronautics Company; Briefing to the European Space Research Organization on Space Station Plans and Programs in Paris, France, June 3-5, 1970.

ASTP Shuttle manipulator demo (1971-1972)

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Caldwell Johnson, co-holder with Maxime Faget of the Mercury capsule patent, was chief of the Spacecraft Design Division at NASA's Manned Spacecraft Center (MSC) in Houston when he proposed that astronauts test prototype Space Shuttle manipulators during Apollo Command and Service Module (CSM) missions in Earth orbit. In a February 1971 memorandum to Faget, MSC's director of Engineering and Development, Johnson described the manipulator test mission as a worthwhile alternative to the Earth survey, space rescue, and joint US/Soviet docking CSM missions then under study.

At the time, the Apollo 18, 19, and 20 lunar missions had been cancelled and the second Skylab space station (Skylab B) appeared increasingly unlikely to reach orbit. NASA managers foresaw that the mission cancellations would leave them with a stock of surplus Apollo spacecraft and Saturn rockets after the last mission to Skylab A. They sought low-cost Earth-orbital missions that would put the surplus hardware to good use and fill the expected multi-year gap in U.S. piloted missions between Skylab and the first Space Shuttle launch.

Johnson envisioned Shuttle manipulators capable of bending and gripping much as do human arms and hands, thus enabling them to hold onto virtually anything. He suggested that a pair of prototype arms be mounted in a CSM Scientific Instrument Module (SIM) Bay (bottom image above), and that the CSM "pretend to be a Shuttle" in operations with the derelict Skylab space station. The CSM's three-man crew could, he told Faget, could use the manipulators to grip and move Skylab. They might also use them to demonstrate a space rescue, capture an "errant satellite," or remove film from SIM Bay cameras and pass it to the astronauts through a special airlock installed in place of the docking unit in the CSM's nose.

Faget enthusiastically received Johnson's proposal (he penned "Yes! This is great" on his copy of the February 1971 memo). The proposal generated less enthusiasm elsewhere, however.

Undaunted, Johnson proposed in May 1972 that Shuttle manipulator hardware replace Earth resources instruments that had been dropped for lack of funds from the planned U.S.-Soviet Apollo-Soyuz Test Project (ASTP) mission (top image above). He asked Faget for permission to perform "a brief technical and programmatic feasibility study" of the concept. Faget gave Johnson leave to prepare a presentation for Aaron Cohen, the manager of the newly created Space Shuttle Program Office at MSC.

In his June 1972 presentation to Cohen, Johnson declared that "[c]argo handling by manipulators is a key element of the Shuttle concept." He noted that CSM-111, the spacecraft tagged for the ASTP mission, would have no SIM Bay, and suggested that a single 28-foot-long Shuttle manipulator could be mounted near the Service Propulsion System (SPS) main engine. During ascent to orbit, the manipulator would ride folded beneath the CSM near the ASTP Docking Module (DM) within the Spacecraft Launch Adapter. During SPS burns, the astronauts in the CSM would stabilize the manipulator by commanding it to grip a handle near the base of the conical Command Module (CM). Johnson had apparently dropped the concept of an all-purpose hand-like "end effector" for the manipulator; he informed Cohen that the end effector design was "undetermined."

The Shuttle manipulator demonstration would take place after CSM-111 undocked from the Soviet Soyuz spacecraft. The astronauts in the CSM would first use a wrist-mounted TV camera to inspect the CSM and DM, then would use the end effector to manipulate "some device" on the DM. They would then command the end effector to grip a handle on the DM, undock the DM from the CSM, and use the manipulator to redock the DM to the CSM. Finally, they would undock the DM and repeatedly capture it with the manipulator.

Johnson estimated that new hardware and modifications to exisitng hardware for the Shuttle manipulator demonstration would add 168 pounds to the CM and 553 pounds to the drum-shaped Service Module. He expected that concept studies and pre-design would be completed in January 1973. Detail design would commence in October 1972 and be completed by July 1, 1973, at which time CSM-111 would undergo modification for the manipulator demonstration.

MSC would build two manipulators in house. The first, for testing and training, would be completed in January 1974. The flight unit would be completed in May 1974, tested and checked out by August 1974, and launched into orbit attached to CSM-111 in July 1975. Johnson optimistically placed the cost of the demonstration at just $25 million.

CSM-111, the last Apollo spacecraft to fly, reached orbit on schedule on July 15, 1975. By then, Caldwell Johnson had retired from NASA. The Shuttle manipulator, the Canada-built Remote Manipulator System, first reached orbit on board the Space Shuttle Columbia during STS-2, the second flight of the Shuttle program, on November 12, 1981 (image below).

Memorandum with attachment, EW/Chief, Spacecraft Design Division, to EA/Director of Engineering and Development, Flight Demonstration of Shuttle docking and cargo handling techniques and equipment using CSM/Saturn 1-B, NASA Manned Spacecraft Center, February 1, 1971.

Memorandum with attachment, EW/Chief, Spacecraft Design Division, to PA/Special Assistant to the Manager, Demonstration of Shuttle manipulators aboard CSM/Soyuz rendezvous and docking mission, NASA Manned Spacecraft Center, May 25, 1972.

Memorandum with attachment, EW/Chief, Spacecraft Design Division, to LA/Manager, Space Shuttle Program Office, Proposal to Demonstrate Shuttle-type Manipulator During Apollo/Soyuz Test Project, NASA Manned Spacecraft Center, June 28, 1972.

Mars Airplane (1978)

2011-10-27T08:36:00.001-07:00

In the 1970s, as U.S. piloted spaceflight retreated to low-Earth orbit, planning for advanced robotic Mars exploration missions came into its own. New information on the martian environment from Mariner 9 and the twin Vikings fueled engineers' imaginations. Many concepts that became actual missions in the 1990s and 2000s first received detailed study in the 1970s. Planners also looked at concepts that have yet to yield missions: Mars sample return, large rovers for very long traverses, small lander networks, and Mars aircraft.

The Ad Hoc Mars Airplane Science Working Group met at NASA's Jet Propulsion Laboratory (JPL) on May 8-9, 1978, to review mission objectives and propose a possible instrument payload weighing between 40 and 100 kilograms. In its report, the Group noted that a Mars Airplane designed for landings and takeoffs would be able to collect samples in places other types of vehicles might find hard to reach. The plane might also be used to deploy small payloads at scattered locations by airdrop or landing. The Group, however, limited its deliberations to using the plane as an aerial survey platform. The Ad Hoc Science Working Group based its planning on a Mars airplane design derived from NASA Dryden Flight Research Center's "MiniSniffer" pilotless plane for sampling Earth's stratosphere.

The 300-kilogram Mars airplane, which would arrive at Mars folded in an lozenge-shaped Viking-type aeroshell, would deploy to a wingspan of 21 meters. It would normally cruise one kilometer above the martian surface, though it would be capable of flying as high as 7.5 kilometers. The 4.5-meter-diameter propeller at the front of its 6.35-meter-long fuselage would pull it through the thin (less than 1% of Earth atmosphere density) martian atmosphere at a cruise speed of between 216 and 324 kilometers per hour.

Mars airplane endurance would depend on payload weight and choice of powerplant. A plane with a 13-kilogram, 15-horsepower hydrazine piston motor, 187 kilograms of hydrazine fuel, and a 100-kilogram payload could fly up to 3000 kilometers in 7.5 hours, while one with a 20-kilogram electric motor, 180 kilograms of advanced batteries and a 40-kilogram payload could fly up to 10,000 kilometers in 31 hours. The Group noted that the plane's short operational lifetime would dictate that its position after Mars atmosphere entry be determined rapidly so that it could be directed quickly to its surface targets.

The Ad Hoc Group assumed that the Mars airplane would carry an inertial guidance system, radar and atmospheric-pressure altimeters, and terrain-following sensors (laser or radar) for navigation, and that these would serve double-duty as science instruments. The Group's selected science payload was intended to characterize possible landing sites for a follow-on Mars sample return mission and also to perform "topical" studies. The latter would address specific questions about Mars: for example, "Is Valles Marineris [Mars's great equatorial canyon system] a rift valley?"

Visual imaging would be "fundamental" to the Mars airplane mission, so would receive top priority in the instrument suite. The Group determined that the airplane would be well-suited to serve as a camera platform because it would offer image resolution intermediate between orbiter and lander cameras and would obtain valuable "oblique" (to the side) images of the surface. A Mars airplane might fly down a sinuous martian outflow channel, for example, collecting high-resolution images of layers exposed in its walls. The Mars airplane camera might be mounted on a movable platform inside a transparent dome on the plane's belly.

Other high-priority investigations would include wind speed, air pressure, and temperature measurements at various altitudes, infrared and gamma-ray spectroscopy and multispectral imaging to determine surface composition, and measurements of local magnetic fields. For magnetic field studies, the plane would fly a grid pattern over a selected region. The magnetometer, which might be mounted on a boom or a wingtip to minimize interference from airplane electrical sources, would detect iron-rich surface materials and buried iron-rich volcanic structures.

Final Report of the Ad Hoc Mars Airplane Science Working Group, JPL Publication 78-89, NASA Jet Propulsion Laboratory, November 1, 1978.

Mars Airplane Presentation Material Presented at NASA Headquarters, JPL 760-198, Part II, Jet Propulsion Laboratory, March 9, 1978.

An expanded robotic program (1963)

2011-10-25T20:40:00.000-07:00

The Apollo Program dominated NASA in the 1960s. Its chief aim was to place a man on the moon ahead of the Soviet Union and before 1970. In December 1963, three of NASA's four approved robotic exploration programs - Ranger, Surveyor, and Lunar Orbiter - focused on the moon. The fourth, Mariner, aimed at Mars and Venus. Apollo requirements - the need to find safe landing sites and to understand lunar conditions well enough to design the Apollo Lunar Excursion Module lander - dominated the moon programs. Beating the Communists to Venus and Mars was a major motivator for Mariner. In short, Cold War geopolitics ruled, not scientific exploration.

On December 2, 1963, NASA Lunar and Planetary Program staffers briefed NASA top brass (Administrator James Webb, Deputy Administrator Hugh Dryden, and Associate Administrator Robert Seamans) with the aim of shifting NASA's robotic program priorities toward science. In his introductory presentation, Lunar and Planetary Program Director Oran Nicks solicited funding to enhance the four extant programs with new science-focused missions. He also sought funding to initiate the new Voyager Mars/Venus program.

Nicks reminded Webb, Dryden, and Seamans that Mariner II had scored an impressive first by flying past Venus in December 1962. He then noted that, one year on, NASA's entire approved planetary program consisted of just two Mars flybys (Mariners III and IV, set for launch in November 1964). He blamed funding cuts and problems with the Centaur upper stage for this surprising dearth of new missions. Mariners planned after 1964 were, he added, "not firm." Nicks then turned the briefing over to his Lunar and Planetary Program managers.

By the time Ranger Program Manager N. William Cunningham stood before Webb, Dryden, and Seamans, Rangers 1 through 5 had failed. Ranger 1 (launched August 23, 1961) and Ranger 2 (launched November 18, 1961), "Block I" vehicles meant to gather data on micrometeoroids, radiation, solar plasma, and magnetic fields in high elliptical Earth orbit, had fallen victim to Atlas-Agena B malfunctions, as had Ranger 3 (launched January 26, 1962), a Block II spacecraft meant to rough-land a seismometer on the moon. Ranger 4 (launched April 23, 1962) and Ranger 5 (launched October 18, 1962), also Block IIs, had suffered electrical failures.

Cunningham began his presentation by telling Webb and his deputies that Ranger 6, a Block III spacecraft designed to snap photos of the moon while plummeting toward destructive impact, would launch in January 1964. He assured them that his engineers had made "many changes in. . . the spacecraft. . . in an effort to improve its chances for success."

Four Block IIIs (Rangers 6 through 9) were expected to photograph the moon by August 1964, then six Block Vs (Rangers 10 through 15) would fly in 1965-1967. Cunningham noted that NASA planned to spend $92.5 million on Block V Rangers. Like the Block IIs, Block V Rangers would attempt to rough-land capsules containing instruments, including possibly a TV system for returning to Earth images of the moon's stark surface. Cunningham called the Block Vs "the only backup" the U.S. had in place for the Surveyor Program, then urged Webb and his lieutenants to add $50 million to the Block V Ranger development budget.

Surveyor Program Manager Benjamin Milwitzky told Webb, Dryden, and Seamans that his program's main purpose was to gather "essential data about the lunar surface. . . needed for manned landings." An Atlas-Centaur rocket would launch the first Surveyor soft-lander in 1965. Milwitzky reported that Surveyor had been intended to carry 300 pounds of science instruments, but that Centaur upper stage problems had forced a cut to between 70 and 100 pounds. He told them that, while the reduced payload would be adequate for scouting Apollo landing sites, many lunar science opportunies would have to be abandoned.

Milwitzky proposed restoring Surveyor's science payload by adding fluorine to the Atlas rocket's liquid oxygen propellant. He urged Webb, Dryden, and Seamans to spend $40 million in 1964-1966 to develop this energetic oxidizer mix for the Atlas.

The first advanced science-focused Surveyor would fly in 1967. A typical advanced Surveyor lander might include a Radioisotope Thermoelectric Generator for providing its instruments with long-term electricity, a drill for subsurface sample collection, sample analysis gear, a geophysical probe that could be lowered down the drill bore hole, a seismometer, a mast-mounted TV system for imaging a large area around the lander in stereo, and a small rover for exploring the landing site and emplacing explosive seismic packages.

Milwitzky ended his presentation by proposing that NASA increase the number of planned Surveyor missions from 17 to 29. He estimated that the 17-mission program would cost $425.5 million; adding 12 more missions would cost an additional $352 million.

Milwitzky then handed off to Lee Scherer, Lunar Orbiter Program Manager. Scherer began his presentation by reminding Webb and his deputies that Lunar Orbiter missions 1 through 5 had been approved for 1966-1967, and that Lunar Orbiters 6 through 10, while not yet formally approved, were planned for 1967-1968. Lunar Orbiter spacecraft would, he said, aim "to obtain, initially, scientific data about the moon and its environment of special importance to the Apollo mission." The approved Lunar Orbiters were intended mainly to photograph areas of the lunar surface accessible to Apollo spacecraft (that is, close to the equator on the nearside, the lunar hemisphere facing Earth).

Scherer proposed that NASA fly five science-oriented Lunar Orbiters in 1968-1969. These might enter orbits inclined to the lunar equator, enabling them to pass over scientifically interesting surface features beyond the equatorial Apollo landing zone. They might also enter lunar polar orbit for whole-moon mapping. Gamma-ray spectrometers and infrared sensors might be used to map lunar mineralogy. Scherer also proposed a mission dedicated to exploring moon/Sun plasma interactions and any lunar magnetic field that might exist. Lunar Orbiters 1 through 10 would cost $198 million; Scherer estimated that adding Lunar Orbiters 11 through 15 would boost the program's cost by $95 million.

The Jet Propulsion Laboratory (JPL) in Pasadena, California, first proposed the ambitious Voyager Mars/Venus series in 1960. In December 1963, Voyager was not yet an approved NASA program, though studies continued at JPL and NASA Headquarters. According to Donald Hearth, the Lunar and Planetary Program Office staffer responsible for Voyager, NASA had allotted $7.1 million for Voyager studies in 1962-1963. Of this, all but $1.3 million had been shifted to cover funding shortfalls in other programs.

Assuming that NASA approved its development, the Voyager spacecraft would comprise three parts: a 2000-pound orbiter with a 2000-pound retro stage and a 2500-pound lander. These would leave Earth together on a Saturn IB with a Centaur third stage. For Mars missions, the Voyager lander would separate from its orbiter during approach to the planet, enter the atmosphere directly from its interplanetary trajectory, and land within 500 kilometers of a target site. It would explore its landing site for six months. After lander separation, the Voyager orbiter would fire the retro stage to slow down so that martian gravity could capture it into Mars orbit.

Hearth told Webb, Dryden, and Seamans that the Voyager 1969 Mars lander would carry an impressive suite of 38 science instruments, including two TV cameras, a sample-collection drill, biology detectors, a microscope, a seismometer, a microphone, and meteorology sensors. Voyager 1969 orbiter instruments would include multicolor stereo TV cameras, an infrared spectrometer for determining surface composition over wide areas, a magnetometer for charting the martian magnetic field, a cosmic dust detector, and a solar X-ray detector.

Though more capable than any other U.S. lunar or planetary spacecraft, the Saturn IB-Centaur-launched Voyagers would pale next to planned Saturn V-launched Advanced Voyagers. Hearth reported that the Saturn V rocket could launch to Mars a 3100-pound orbiter and one or more direct-entry landers weighing a total of 33,000 pounds. These "large lander laboratories" might carry rovers, balloons, and hovercraft for exploration beyond their landing sites. Alternately, the Advanced Voyager orbiter might carry a large retro stage that would enable it to retain its lander until after it achieved Mars orbit. Lander descent from Mars orbit would improve landing accuracy, Hearth stated.

Hearth estimated that the Voyager Program would cost $2.9 billion over 11 years. Assuming timely approval, NASA could launch Voyager test flights in 1967 and 1968, Voyager Mars missions in 1969, 1971, and 1973, Voyager Venus missions in 1970 and 1972, and Advanced Voyager Mars missions in 1973 and 1975.

Within a week of the December 2 briefing, James Webb informed Oran Nicks that NASA could not afford to expand its robotic lunar and planetary programs. Though Ranger 6 was an embarrassing failure, Rangers 7 and 8 succeeded, and the program concluded with the successful science-focused Ranger 9 mission to Alphonsus crater in March 1965. All were Block III spacecraft; no Block V Ranger ever flew. Five Lunar Orbiters mapped the moon between August 1966 and January 1968. Lunar Orbiters 4 and 5 were science-focused missions in a near-polar orbits. Surveyor ended with its seventh flight, a science-focused mission to the young crater Tycho in January 1968.

The 1960s and early 1970s saw a total of seven successful Mariners. In July 1965, Mariner IV became the first spacecraft to fly past Mars. No Mariner ever carried an atmosphere probe, but Mariner 9 (May 1971-October 1972) became the first Mars orbiter. Mariner 10, the last of the series, became the first spacecraft to fly past Mercury (in fact, it flew past the planet three times, in March 1974, September 1974, and March 1975).

Voyager lingered on until August 1967, when Congress refused to fund its development. NASA then proposed a Mariner-based Mars landing program called Viking, which received Congressional approval in 1968. Two Viking orbiter-lander pairs explored Mars beginning in 1976. The name Voyager was subsequently resurrected for the Mariner-derived outer planets probes which explored Jupiter, Saturn, Uranus, and Neptune between 1979 and 1989.

The images above display the Mars/Venus Voyager, Ranger, and Surveyor launch vehicles. At the top is the Apollo 7 Saturn IB rocket. Saturn IB was never used with a Centaur upper stage. The middle image depicts the Ranger 4 Atlas-Agena B, and the Surveyor 5 Atlas-Centaur rocket is at bottom.

Briefing for the Administrator on Possible Expansion of Lunar and Planetary Programs, NASA Headquarters, December 2, 1963.

Progressive Mars landing capsule program (1966)

2011-10-22T18:07:00.000-07:00

In May 1966, Carlos de Moraes and Robert Scarborough, engineers with The Martin Company, described a program of increasingly capable automated Mars missions for the 1970s. Although they did not mention the name "Voyager," they had developed their proposed program in support of NASA's automated Voyager Mars/Venus program (top link below). De Moraes was Martin's Voyager Program Director and Scarborough was Martin's Voyager Engineering Technical Director.

Their apparent reluctance to tie their plan overtly to Voyager might have stemmed from controversy surrounding the program following the Mariner IV mission. In July 1965, the 574-pound Mariner IV spacecraft became the first to return data from Mars. As it flew by Mars, it captured 21 grainy black-and-white images of the southern hemisphere showing discouragingly moon-like craters and confirmed that the planet has a carbon dioxide atmosphere less than 1% as dense as Earth's. It detected no obvious signs of water.

Mariner IV's findings cast doubt on Voyager's primary mission, which was to seek out martian life, and forced costly design changes, such as substitution of heavy landing rockets for lightweight parachutes. The required design changes pushed Voyager's estimated pricetag past $1 billion. In 1966, this was an unheard-of sum for a robotic space program.

De Moraes and Scarborough's "progressive" Mars landing capsule program was based on several key assumptions. The first was that it would proceed in the manner of any scientific venture; that is, that it would begin by answering "fundamental" questions and move toward "more sophisticated experimentation." Early missions would better define martian atmosphere and surface characteristics, making easier the job of the engineer when time came to design more complex and capable Mars capsules.

Their second assumption was based on the fact that Mars missions launched in 1975, 1977, and 1979 would need more energy (hence propellants) to reach Mars than those launched in 1969, 1971, and 1973. The authors calculated that launching a spacecraft toward Mars in 1975 (the least favorable Earth-Mars transfer opportunity) would need nearly twice as much energy as launching the same spacecraft in 1971 (the most favorable Earth-Mars transfer opportunity).

Third, de Moraes and Scarborough assumed that new Mars missions would leave Earth every 26 months; that is, during every minimum-energy Earth-Mars transfer opportunity. This would, they wrote, place missions too close together to permit data from one to be used in planning and developing the next. The 1973 mission, for example, could not be planned on the basis of data from the 1971 mission, though the 1975 mission could.

Their fourth and last assumption was that the three-stage Saturn V would be their program's main launch vehicle. This was because it could place up to 30 tons on course for Mars. They noted, however, that the giant rocket was unlikely to become available for use in the 1969 Earth-Mars transfer opportunity because of Apollo moon program needs.

Based on these four assumptions, the Martin engineers developed a program plan spanning six Earth-Mars transfer opportunities between 1969 and 1979. It would not actually bear their stamp until 1971, however; this was because they recommended that NASA should stick with its pre-existing plan to launch an 850-pound Mariner on a Mars flyby mission in 1969. The 1969 Mariner, an upgrade of the Mariner IV design, would launch on an Atlas rocket with a Centaur upper stage.

Scarborough and de Moraes proposed two alternatives for 1971. If Saturn V availability remained a problem, then NASA would launch on an Atlas-Centaur a Mariner flyby spacecraft carrying a 150-pound direct-entry capsule with 38 pounds of science instruments. The capsule would separate from the flyby Mariner, enter Mars's atmosphere without first capturing into Mars orbit, radio atmospheric data to Earth during descent, and be destroyed upon impact with Mars's surface.

Alternately, 1971 might see a single Saturn V launch two 2500-pound orbiters, each carrying up to five 600-pound weather station capsules. Upon reaching Mars, a 6.5-ton liquid-propellant propulsion module would ignite to place the twin spacecraft into elliptical Mars orbit, then would separate.

Each spherical, 16-inch-diameter capsule would have strapped to it an 8.3-foot-diameter conical heat shield and a solid-propellant deorbit rocket motor. The capsules would separate from the orbiters one by one over several orbits to enable them to land at sites widely scattered over the planet. Following the deorbit burn and a fiery atmosphere entry, each would eject its heat shield and lower to Mars's surface using solid-propellant rocket motors and a ballute ("balloon-parachute") or a conventional parachute. The capsules would be capable of compensating for lateral velocity imparted by martian winds, which would help to protect them from damage during landing.

After touchdown, each capsule would tumble to a stop and right itself by extending petal-shaped legs. It would then deploy a radio antenna/weather sensor mast. The battery-powered capsules would transmit weather data to Earth for up to 58 hours.

The 1973 opportunity would see a Saturn V launch two 2500-pound orbiters and four 3000-pound capsules (two per orbiter). Because capsule mass would be double that of the 1971 spacecraft, a 7.7-ton propulsion module would be needed to slow the spacecraft so that Mars's gravity could capture them into orbit. The capsule heat shields would measure 11.9 feet in diameter. Radioisotope Thermal Generators (RTGs) would permit the 1973 capsules to operate on Mars for at least one martian year (about two Earth years), during which time they would employ 290 pounds of science instruments to return data on martian biology, geology, meteorology, and atmospheric composition.

In the unfavorable 1975 Mars-Earth transfer opportunity, a Saturn V would launch toward Mars two 2500-pound orbiters, two 3000-pound capsules (one per orbiter), and, because Mars approach speed would be greater than in 1971 or 1973, a 10.1-ton Mars orbit insertion propulsion module. Apart from the reduced number of capsules and enhanced propulsion module, the mission would resemble its predecessor in 1973.

In 1977, a Saturn V would launch two 3500-pound flyby spacecraft based on the 1971/1973/1975 orbiter design. Each would carry one 6500-pound direct-entry landing capsule. Science payload would account for more than 1000 pounds of each capsule's mass. After Mars atmosphere entry, the capsules would discard their 18-foot-diameter heatshields and land on "soft landing leg type gear" similar to that planned for the Surveyor automated moon landers and the manned Apollo Lunar Module.

The flyby spacecraft would play no further role in the 1977 mission after they released their capsules. Scarborough and de Moraes proposed that, if previous orbiters had achieved their orbital science objectives, then beginning in 1977 the orbiter and flyby spacecraft should be stripped down so that they would include only those systems essential for delivering a lander to Mars's vicinity. The mass saved by simplifying the orbiter/flyby spacecraft would enable more massive landing capsules, some of which might deploy automated rovers on Mars.

The final mission of de Moraes and Scarborough's program (though probably not the final U.S. mission to Mars) would be a repeat of the 1977 mission, but with one important difference. Prior to 1979, capsules would enter Mars's atmosphere on ballistic paths. The Martin engineers proposed that, beginning in 1979, lifting-body heat shields should be adopted to enable heavier capsules and more precise landings.

Congress canceled Voyager in August 1967, leaving NASA with no planetary exploration program for the 1970s. Little came of de Moraes and Scarborough's progressive capsule plan, though their company would play a key role in robotic Mars exploration in the 1970s and beyond. In 1968, Congress approved Viking, which would launch twin orbiter/lander combinations to Mars in 1973 on Titan IIIE/Centaur rockets (images above). Martin Marietta, as The Martin Company was by then known, became prime contractor for the lander component of the NASA Langley Research Center-managed program. The Jet Propulsion Laboratory in Pasadena, California, which had built the Mariners, became Viking orbiter contractor.

In July-August 1969, Mariners 6 and 7 flew past Mars, returning images of its south pole ice cap, ancient southern hemisphere crater fields, and inner moon Phobos. Mariner 9 then explored Mars from orbit for 11 months starting in November 1971, returning more than 7300 images. These revealed giant volcanoes and canyons, Mars's lightly cratered, geologically young northern plains, and abundant signs of past liquid water, including huge outflow channels. Mariner 9 images were used for preliminary Viking landing site selection.

Mariner 9 data reinvigorated the quest for life on Mars. Despite new enthusiasm for the planet, however, Nixon-era NASA budget cuts slowed development of the Viking spacecraft, causing their launches to slip to the unfavorable 1975 Earth-Mars transfer opportunity. This forced mass-reduction measures, including removal of one of the suite of four biology experiments planned for each of the Viking landers.

On July 20, 1976, the 1346-pound Viking 1 lander separated from its Mariner-derived orbiter and became the first spacecraft to successfully land on Mars. It set down in Chryse Planitia, at a site north of the confluence of several large outflow channels. The Viking 2 lander (images below) touched down on September 3, 1976, on the seasonally frosty northern plain of Utopia Planitia.

The three Viking biology experiments returned equivocal results at both landing sites that were generally interpreted as negative, damping enthusiasm for Mars exploration and helping to ensure that proposals for follow-on Mars missions, some based on Viking technology, would not gain support (middle and bottom links below). The U.S. would not launch another Mars spacecraft until the ill-fated Mars Observer in 1992, and would not launch a successful Mars spacecraft until Mars Pathfinder in 1996.

"Progressive Mars Capsule Mission Capability," Carlos de Moraes and Robert Scarborough, The Search for Extraterrestrial Life, Vol. 22, Advances in the Astronautical Sciences, James Stephen Hanrahan, editor, pp. 55-84; paper presented at the Twelfth Annual Meeting of the American Astronautical Society in Anaheim, California, May 23-25, 1966.

http://beyondapollo.blogspot.com/2010/05/first-voyager-1967.html

http://beyondapollo.blogspot.com/2010/04/phobos-viking-1972.html

http://beyondapollo.blogspot.com/2009/10/advanced-viking-based-missions-1975.html

Galileo: Uncontrolled STS Orbiter Reentry (1988)

2011-10-16T17:29:00.000-07:00

The U.S. Congress authorized new-start funding for the Jupiter Orbiter and Probe (JOP) on July 19, 1977. When JOP development began officially on October 1, 1977, NASA planned to launch it in January 1982 on STS-23, the 23rd operational flight of the Space Transportation System (STS).

Until 1986, the STS was intended to replace all U.S. expendable launch vehicles. The Space Shuttle was the centerpiece of the STS. At liftoff, the Shuttle stack comprised twin reusable solid-propellant Solid Rocket Boosters (SRBs), a reusable manned Orbiter with a 15-by-60-foot payload bay and three Space Shuttle Main Engines (SSMEs), and an expendable External Tank (ET) containing liquid hydrogen and liquid oxygen propellants for the SSMEs.

The STS also included upper stages for launching satellites carried into space in the payload bay beyond the Shuttle's maximum orbital altitude. Until the mid-1980s, many in NASA hoped that a reusable Space Tug would eventually replace the expendable upper stages.

At the start of STS-23 (and, indeed, all Space Shuttle missions), the three SSMEs and twin SRBs would ignite to push the Shuttle stack off the launch pad. SRB separation would occur 128 seconds after liftoff at an altitude of about 155,900 feet and a speed of about 4417 feet per second. The three SSMEs would operate until 510 seconds after liftoff, by which time the Orbiter and ET would be 362,600 feet above the Earth traveling at about 24,310 feet per second. The SSMEs would then shut down and the ET would separate, tumble, and reenter the atmosphere over the Indian Ocean. The Orbiter, meanwhile, would ignite its twin Orbital Maneuvering System engines to circularize its orbit above the atmosphere.

After the STS-23 Shuttle Orbiter reached 150-nautical-mile-high low-Earth orbit (LEO), its crew would open its payload bay doors and release JOP and its three-stage solid-propellant Interim Upper Stage (IUS). After the Orbiter moved a safe distance away, the IUS would ignite to begin JOP's two-year direct voyage to Jupiter.

In February 1978, NASA gave JOP the name Galileo. Largely because of its reliance on the STS, Galileo suffered a series of costly delays, redesigns, and Earth-Jupiter trajectory changes. The first of these was, however, not the fault of the STS. As Galileo's design firmed up, it put on weight, and was soon too heavy for the three-stage IUS to launch directly to Jupiter.

In January 1980, NASA decided to split Galileo into two spacecraft. The first, the Jupiter Orbiter, would leave Earth in February 1984. The second, an interplanetary bus carrying Galileo's Jupiter atmosphere probe, would launch the following month. They would each depart LEO on a three-stage IUS and arrive at Jupiter in late 1986 and early 1987, respectively.

In late 1980, under pressure from Congress, NASA opted to launch the Galileo Orbiter and Probe out of LEO together on a liquid hydrogen/liquid oxygen-fueled Centaur upper stage. Centaur, a mainstay of robotic lunar and planetary programs since the 1960s, was expected to provide 50% more thrust than the three-stage IUS. Modifying it so that it could fly safely in the Shuttle Orbiter's payload bay would, however, delay Galileo's Earth departure until April 1985. The spacecraft would arrive at Jupiter in 1987.

Another delay resulted when David Stockman, director of President Ronald Reagan's Office of Management and Budget, put Galileo on his "hit list" of Federal government projects to be scrapped in Fiscal Year 1982. The planetary science community campaigned successfully to save Galileo, but NASA lost the Centaur and three-stage IUS. The latter had been plagued by development delays.

In January 1982, NASA announced that Galileo would depart Earth orbit in April 1985 on a two-stage IUS with a solid-propellant kick stage. The spacecraft would then circle the Sun and fly past Earth for a gravity-assist that would place it on course for Jupiter. The new plan would add three years to Galileo's flight time, postponing its arrival at Jupiter until 1990.

In July 1982, Congress overruled the Reagan White House when it mandated that NASA launch Galileo from LEO on a Centaur. The move would postpone its launch to May 20, 1986; however, because the Centaur could boost Galileo directly to Jupiter, it would reach its goal in 1988, not 1990. NASA designated the STS mission meant to launch Galileo STS-61-G.

There matters rested until January 28, 1986, when, 73 seconds into mission STS-51-L, the Orbiter Challenger was destroyed. A joint between two of the cylindrical segments making up the Shuttle stack's right SRB leaked hot gases that rapidly eroded O-ring seals. A torch-like plume formed and impinged on the ET and the lower strut linking the ET to the SRB. The plume breached and weakened the ET's liquid hydrogen tank, causing the strut to separate. Still firing - for a solid-rocket motor cannot be turned off once ignited - the right SRB pivoted on its upper attachment and crushed the ET's liquid oxygen tank. Hydrogen and oxygen mixed and ignited in a giant fireball.

Despite appearances, Challenger did not explode. Instead, the Orbiter began a tumble while moving at about twice the speed of sound in a relatively dense part of Earth's atmosphere. This subjected it to severe aerodynamic loads, causing it to break into several large pieces. The pieces, which included the crew compartment and the tail section with its three SSMEs, emerged from the fireball more or less intact. The mission's main payload, the TDRS-B data relay satellite, remained attached to its two-stage IUS as Challenger's payload bay disintegrated around it.

The pieces arced upward for a time, reaching a maximum altitude of about 50,000 feet, then fell, tumbling, to crash into the Atlantic Ocean within view of the Shuttle launch pads at Kennedy Space Center, Florida. The crew compartment impacted 165 seconds after Challenger broke apart and sank in water about 100 feet deep.

NASA grounded the STS for 32 months. During that period, it put in place new flight rules, abandoned potentially hazardous systems and missions, and, where possible, modified STS systems to help improve crew safety. On June 19, 1986, NASA canceled the Shuttle-launched Centaur. On November 26, 1986, it announced that a two-stage IUS would launch Galileo out of LEO. The Jupiter spacecraft would then perform gravity-assist flybys of Venus and Earth. On March 15, 1988, NASA scheduled Galileo's launch for October 1989, with arrival at Jupiter in December 1995.

One month after NASA unveiled Galileo's newest flight plan, Angus McRonald, an engineer at the Jet Propulsion Laboratory (JPL) in Pasadena, California, completed a brief report on the possible effects on Galileo and its IUS of a Shuttle accident during the 382-second period between SRB separation and SSME cutoff. McRonald was not specific about the nature of the "fault" that would produce such an accident, though he assumed that the Shuttle Orbiter would be separated from the ET and tumbling out of control. He based his analysis on data provided by NASA Johnson Space Center in Houston, Texas, where the Space Shuttle Program was managed.

McRonald also examined the effects of aerodynamic heating on Galileo's twin electricity-generating Radioisotope Thermoelectric Generators (RTGs). The RTGs would each carry 18 General Purpose Heat Source (GPHS) modules containing four iridium-clad plutonium dioxide pellets each. The GPHS modules were encased in graphite and housed in protective aeroshells, making them unlikely to melt following an accident during Shuttle ascent. In all, Galileo would carry 34.4 pounds of plutonium.

McRonald assumed that both the Shuttle Orbiter and the Galileo/IUS combination would break up when subjected to atmospheric drag deceleration equal to 3.5 times the pull of gravity at Earth's surface. Based on this, he determined that the Orbiter and its Galileo/IUS payload would always break up if a fault leading to "loss of control" occurred following SRB separation.

The Shuttle Orbiter would not break up as soon as loss of control occurred, however. At SRB separation altitude, atmospheric density is low enough that the spacecraft would be subjected to only about 1% of the drag that tore apart Challenger. McRonald determined that the Shuttle Orbiter would ascend unpowered and tumbling, attain a maximum altitude, and fall back into the atmosphere, where drag would rip it apart.

He calculated that, for a fault that occurred 128 seconds after liftoff - that is, at the time the SRBs separated - the Shuttle Orbiter would break up as it fell back to 101,000 feet of altitude. The Galileo/IUS combination would fall free of the disintegrating Orbiter and break up at 90,000 feet, then the RTGs would fall to Earth without melting. Impact would take place in the Atlantic about 150 miles off the Florida coast.

For an intermediate case - for example, if a fault leading to loss of control occurred 260 seconds after launch at 323,800 feet of altitude and a speed of 7957 feet per second - then the Shuttle Orbiter would break up when it fell back to 123,000 feet. Galileo and its IUS would break up at 116,000 feet, and the RTG cases would melt and release the GPHS modules between 84,000 and 62,000 feet. Impact would occur in the Atlantic about 400 miles from Florida.

A fault that took place within 100 seconds of planned SSME cutoff - for example, one that caused loss of control 420 seconds after launch at 353,700 feet of altitude and at a speed of 20,100 feet per second - would result in an impact far downrange because the Shuttle Orbiter would be accelerating almost parallel to Earth's surface when it occurred. McRonald calculated that Orbiter breakup would take place at 165,000 feet and the Galileo/IUS combination would break up at 155,000 feet.

McRonald found, surprisingly, that Galileo's RTG cases might already have melted and released their GPHS modules by the time Galileo and the IUS disintegrated. He estimated that the RTGs would melt between 160,000 and 151,000 feet of altitude. Impact would occur about 1500 miles from Kennedy Space Center in the Atlantic west of Africa.

Impact points for accidents between 460 seconds and SSME cutoff at 510 seconds would be difficult to predict, McRonald noted. He estimated, however, that loss of control 510 seconds after liftoff would lead to wreckage falling in Africa, about 4600 miles downrange.

McRonald determined that Galileo's RTG cases would always reach Earth's surface intact if an accident leading to loss of control occurred between 128 and 155 seconds after liftoff. If the accident occurred between 155 and 210 seconds after launch, then Galileo's RTG cases "probably" would not melt. If it occurred 210 seconds after launch or later, then the RTG cases would always melt and release the GPHS modules.

STS flights resumed in September 1988 with the launch of the Orbiter Discovery on mission STS-26. On October 18, 1989, during mission STS-34, the Galileo/two-stage IUS combination was raised out of Shuttle Orbiter Atlantis's payload bay on an IUS tilt table and released (middle and bottom images above). The IUS ignited a short time later to propel Galileo toward Venus.

Galileo passed Venus on February 10, 1990, adding nearly 13,000 miles per hour to its speed. It then flew past Earth on December 8, 1990, gaining enough speed to enter the Main Belt of asteroids between Mars and Jupiter, where it encountered the asteroid Gaspra on October 29, 1991.

Galileo's second Earth flyby on December 8, 1992 placed it on course for Jupiter. The spacecraft flew past the Main Belt asteroid Ida on August 28, 1993 and had a front-row seat for the Comet Shoemaker-Levy 9 Jupiter impacts in July 1994.

Flight controllers commanded Galileo to release its Jupiter atmosphere probe on July 13, 1995. The spacecraft relayed data from the probe as it plunged into Jupiter's atmosphere on December 7, 1995. Galileo fired its main engine the next day to slow down so that Jupiter's gravity could capture it into orbit.

Galileo spent the next eight years touring the Jupiter system. Despite difficulties with its main antenna and its tape recorder, it returned invaluable data on Jupiter, its magnetosphere, and its moons over the course of 34 orbits of the giant planet.

As Galileo neared the end of its propellant supply, NASA decided to dispose of it to prevent it from accidentally crashing on and possibly contaminating Europa, the ice-encrusted, tidally warmed ocean moon judged by some to be of high biological potential. On September 21, 2003, the venerable spacecraft dove into Jupiter's banded clouds and disintegrated.

Galileo: Uncontrolled STS Orbiter Reentry, JPL D-4896, Angus D. McRonald, Jet Propulsion Laboratory, April 15, 1988.

http://beyondapollo.blogspot.com/2011/01/sts-flight-assignments-1977.html

OASIS modules (2001, 2002)

2011-10-09T20:36:00.001-07:00

As a general rule, electric (ion) propulsion uses little propellant and accelerates spacecraft slowly, while chemical propulsion uses much propellant and accelerates spacecraft rapidly. This means that electric propulsion requires weeks or months to reach speeds chemical propulsion can attain in minutes or hours. As Ernst Stuhlinger noted in 1959, this suggests that spacefarers should use chemical propulsion for astronaut transport and electric propulsion for most cargoes.

In October 2001, at the 52nd International Astronautical Federation Congress in Toulouse, John Mankins of the Advanced Projects Office at NASA Headquarters and Daniel Manzanek of NASA Langley Research Center (LaRC) described an advanced-technology automated Hybrid Propellant Module (HPM) that would form the centerpiece of a multi-modular space transportation architecture. The HPM, they explained, would integrate "the best features of both chemical and electric transportation architectures."

The HPM concept originated in 2000 as part of LaRC's Orbital Aggregation and Space Infrastructure Systems (OASIS) "framework." OASIS, a component of LaRC's Revolutionary Aerospace Systems Concepts program, emphasized a stable of reusable modules (images above) that could be combined in different ways to carry out a range of missions. These would occur mainly in the region of space bounded by the moon's orbit - Low-Earth orbit (LEO), geosynchronous orbit, cislunar space, the Earth-moon Lagrange-1 (L1) point, lunar orbit, and the moon's surface - but would also include the Earth-moon Lagrange-2 (L2), Earth-Sun L1, and Earth-Sun L2 points, which lie well beyond the moon.

OASIS work complemented that of the NASA-wide Decadal Planning Team (DPT)/NASA Exploration Team (NExT), which dubbed the Earth-moon-L points region "Earth's Neighborhood." The DPT, initiated in May-June 1999 by President William Clinton's Office of Management and Budget (OMB), was a high-level attempt to blueprint realistic yet innovative and flexible space architectures for the 21st century. It evolved into the NeXT by late 1999.

One may speculate that DPT/NeXT was begun late in President Clinton's second term with the aim of bearing fruit during the Administration of Al Gore. A precedent existed: President Ronald Reagan dropped his opposition to the revival of the National Space Council in the final months of his Administration at the request of his Vice-President, George H. W. Bush, who subsequently won the 1988 election and succeeded him as President.

As a U.S. Senator, Gore was critical on fiscal grounds of the Space Exploration Initiative President Bush unveiled in July 1989, but he showed considerable interest in space after he was sworn in as Clinton's Vice President in January 1993. After the disputed 2000 election, in which Gore won the popular vote but did not become President because voting irregularities in Florida awarded its electoral votes to George W. Bush, Gore's interest in space persisted; he was, for example, present at the Jet Propulsion Laboratory for the landing of the Mars Exploration Rover Spirit in January 2004.

Because it began without a dramatic presidential speech, the DPT has been portrayed as secretive. In fact, it was not unusual; most in-house NASA advance planning exercises have begun without a lofty rhetorical preamble. The DPT exercise recognized that, if NASA is to be forward-looking, it must perform advance planning as part of its normal business. High-profile speeches proclaiming grand space goals, while gratifying, serve mainly to rally opposition to such advance planning.

The HPM would have an empty mass of 3,940 kilograms and would measure 14.2 meters long. It would hold up to 15,070 kilograms of xenon (Xe) and 31,140 kilograms of cryogenic liquid oxygen (LOX) and liquid hydrogen (LH2). The Xe would serve as propellant for solar-electric propulsion (SEP) thrusters and the LOX/LH2 would supply chemical rocket engines. The HPM's docking units, located at fore and aft, would include ducts for piping propellants to docked propulsion modules. The HPM could be refilled in space and reused many times.

Twin solar arrays would provide the module with the 3.1 kilowatts of electricity required to operate its systems. Lacking any propulsion or reaction control system (RCS) of its own, the HPM would rely on electrically powered spinning momentum wheels for attitude control.

A typical HPM-based piloted mission to the moon and back would begin with launch of an HPM with full Xe, LH2, and LOX tanks. It would reach 400-kilometer-high circular low-Earth orbit (LEO) on board either a new-design reusable piloted shuttle or an expendable launch vehicle (ELV). After separating from its launcher, the HPM would extend its solar arrays and spin up its momentum wheels.

Another shuttle or ELV would place into LEO an automated SEP module. The drum-shaped module would extend twin triangular solar arrays, then would use chemical-propellant RCS jets to rendezvous and dock automatically with the waiting HPM. The SEP module would then activate its thrusters to begin a voyage to Earth-moon L1 that would last up to 270 days. Ducts in the SEP module docking unit would accept Xe pumped from the HPM docking unit ducts.

The slow trip to L1 would mean that the HPM/SEP module combination would linger within the Earth-girdling Van Allen Radiation Belts. Radiation trapped in the belts would degrade solar arrays, reducing the amount of electricity they could supply. Mankins and Manzanek estimated that high-efficiency radiation-resistant arrays would become available within 15 years.

In common with the DPT, Mankins and Manzanek assumed that NASA would establish a small inflatable "Gateway" space station in halo orbit about the Earth-moon L1 point, five-sixths of the way to the moon (link below). Beginning in about 2016, the L1 Gateway would serve as a jumping-off place for astronaut excursions to the moon and other destinations in Earth's Neighborhood.

Upon arrival at L1, the HPM's Xe tanks would be nearly empty while its LOX and LH2 tanks would remain full. The SEP module would turn off its electric thrusters and use its RCS jets to rendezvous and dock itself and the HPM with the L1 Gateway station using the HPM's free docking unit.

A future shuttle would then transport a Crew Transfer Vehicle (CTV) and Chemical Transfer Module (CTM) to the International Space Station (ISS) in LEO. The CTV would include a pair of solar arrays and an inflatable crew module. The CTM, also fitted with twin solar arrays, could operate alone as a "space tug" or docked to an HPM as a propulsion module. Robot arms on the ISS and future shuttle would berth the CTV/CTM combination to one of the station's nadir-facing docking ports, then ISS astronauts would inflate and outfit the CTV crew module (top image below).

A second HPM with full Xe, LOX, and LH2 tanks would then reach LEO on a future shuttle or ELV. The CTM would undock from the CTV attached to the ISS and rendezvous and dock with the second HPM. The CTM/HPM combination would then return automatically to the ISS and dock with the CTV using the HPM's free docking unit.

After astronauts boarded the CTV, the CTV/HPM/CTM combination would undock from the ISS and move away from the station using the CTM's RCS jets. Upon reaching a safe distance, the twin CTM engines would ignite and burn until they had nearly emptied the HPM's LH2 and LOX tanks. Propellant ducts in the CTM docking unit would accept LH2 and LOX pumped from the HPM docking unit ducts.

As was the case during the Apollo Program, passage through the Van Allen Belts would be rapid, limiting astronaut radiation exposure. After a trip of only a few days, the CTV/HPM/CTM combination would dock at a vacant port on the L1 Gateway station. The combination's HPM would reach Earth-moon L1 bearing a full load of Xe.

Before the astronauts could board a reusable chemical-propellant moon lander docked at the L1 Gateway and complete the last leg of their journey to the moon, the HPMs and other modules would need to be shuffled to ensure that the crew could return to LEO quickly in the event of an emergency. First, the CTM/HPM with full Xe tanks combination would undock from the CTV and back away from the L1 Gateway, then the SEP module/HPM module with full LOX/LH2 tanks combination would undock from the L1 Gateway and dock with the CTV.

The CTM/HPM combination would dock at the L1 Gateway port the SEP module/HPM combination had vacated. The SEP module would then undock from the CTV/HPM combination. The CTM would undock and take the SEP module's place, forming a CTV/HPM with full LOX and LH2 tanks/CTM combination. Finally, the SEP module would dock with the HPM with full Xe tanks.

Mankins and Manzanek envisioned that this complex module-shuffling "choreography" would be entirely automated. This would free the astronauts to conduct other activities, such as preparing for their excursion to the lunar surface.

Following their lunar surface visit, the astronauts would return in the reusable moon lander to the L1 Gateway and transfer to the CTV/HPM/CTM combination. They would undock, move a safe distance away from the L1 Gateway station, and ignite the twin CTM engines for a speedy return to the ISS. The SEP module/HPM combination would, meanwhile, depart the L1 Gateway and begin a slow return to LEO.

Mankins and Manzanek estimated that the technologies needed to build their HPM would become available within 15 years. In addition to the radiation-resistant solar arrays mentioned earlier, these would include zero-boil-off systems for containing LOX and LH2 propellants without loss for up to a decade; autonomous rendezvous and docking, propellant transfer, navigation, and vehicle health monitoring systems; long-life electric and chemical propulsion systems with parts easily replaceable in space; and low-mass spacecraft structures and micrometeoroid/orbital debris/radiation shields.

In a report published one year after Mankins and Manzanek presented their paper, six advanced propulsion engineers at NASA Glenn Research Center (GRC) described a refined OASIS SEP module design (bottom image below). Their 11,300-kilogram SEP module, a gossamer assemblage of trusses, solar arrays, and pallets, was designed to transfer an HPM containing 36,300 kilograms of LOX/LH2 from the ISS to Earth-moon L1 in less than 270 days.

The GRC SEP module would comprise two lightweight thin-film solar arrays with a combined area of 2685 square meters, a "base pallet" mounted near the junction of the solar array booms for holding an HPM, a 96-kilogram, 20-meter-long boom arm modeled on the coilable mast deployed during the Shuttle Radar Topography Mission (STS-99, February 2000), a pallet bearing eight or nine electric-propulsion thrusters, and a tank holding 2000 kilograms of Xe for minor maneuvers and station-keeping (this last would replace the chemical-propellant RCS of the LaRC SEP module design).

The GRC SEP module's square solar arrays would generate 448 kilowatts of electricity for its electric thrusters. The thruster pallet would be mounted at the end of the boom arm to prevent Xe ions from inadvertently colliding with and damaging the arrays.

The SEP module thrusters would use 12,200 kilograms of Xe propellant drawn from the HPM during the slow transfer from LEO to the L1 Gateway. The authors noted that the thrusters would operate only while the arrays were in direct sunlight (that is, not while the SEP module passed through the shadow of the Earth or the moon). This would eliminate the need for bulky energy storage systems, such as batteries.

They envisioned that, after the two modules arrived at the L1 Gateway, the SEP module would undock from the HPM and move away using its Xe maneuvering propellant to await a new mission. The GRC engineers calculated that their SEP module could perform two ISS-L1 Gateway round trips before radiation degraded its solar arrays to the point where they could not energize its thrusters.

"The Hybrid Propellant Module (HPM): A New Concept for Space Transfer in the Earth's Neighborhood and Beyond," IAF-01-V3.03, John C. Mankins and Daniel D. Mazanek; paper presented at the 52nd Congress of the International Astronautical Federation in Toulouse, France, October 1-5, 2001.

Solar Electric Propulsion Vehicle Design Study for Cargo Transfer to Earth-Moon L1, NASA/TM-2002-211970 (also AIAA-2002-3971), Timothy R. Sarver-Verhey, Thomas W. Kerslake, Vincent K. Rawlin, Robert D. Falck, Leonard J. Dudzinski, and Stephen R. Oleson, October 2002.

http://beyondapollo.blogspot.com/2011/07/100-day-mission-to-sun-earth-l2-1999.html

Stuhlinger's Cosmic Butterfly (1954)

2011-10-06T20:55:00.001-07:00

Ernst Stuhlinger (bottom image above) owed his place in the Guided Missile Development Division at Redstone Arsenal in Huntsville, Alabama, to Operation Paperclip, the U.S. Army's effort to retrieve rocket engineers and V-2 missiles and assembly hardware from the smoking ruins of the Nazi German empire. The U.S. military was (of course) mainly interested in tapping their talents to build missiles, but the Germans did their energetic best to cultivate other aspects of rocketry in the United States. For example, the most famous of the German rocketeers, Wernher von Braun, set out in the 1950s with help from Collier's magazine and Walt Disney to "sell" space stations and moon and Mars expeditions to the American citizenry.

In a paper presented at the Fifth International Astronautical Federation Congress in 1954, Stuhlinger pitched interplanetary travel using low-thrust ion (electric) propulsion. The spacecraft design he proposed comprised three major parts: the crew/payload compartment at the ship's center; a 146.4-ton multi-unit solar-electric power system; and a multi-chamber low-thrust ion drive system.

Stuhlinger provided no details about the layout of his ship's crew/payload compartment, other than that it would carry up to 50 tons of crew and cargo. He did, however, offer abundant details on his solar-electric power and ion drive systems.

The former would include two 350-meter-wide "wings," each comprising 19 independent electricity-generating "sub-units." A dish-shaped mirror 50 meters wide would form the largest component of each 4400-kilogram sub-unit. Stuhlinger wrote that his spacecraft would gain speed very slowly, accelerating at a rate equal only to about 1/1000th of Earth's surface gravity. At such a low rate of acceleration, a fork dropped in the ship's messroom would need more than five minutes to strike the floor. The low acceleration would mean that the mirrors would have no need of robust construction; they might comprise "thin aluminum foil with a very light supporting frame."

Each 450-kilogram, 2000-square-meter mirror would concentrate sunlight onto a boiler, causing a working fluid within it to turn to steam. The steam would drive a turbine, which would in turn drive a generator capable of producing 200 kilowatts of electricity. The steam, meanwhile, would enter a disk-shaped radiator cooler and condense back into fluid. Boiler, turbine/generator, and cooler would revolve together as a unit, completing one revolution every 10 seconds. This would generate acceleration that would cause the working fluid to flow to the cooler's outer rim, from which it would be pumped back to the boiler.

The multi-unit solar-electric power system would have built-in redundancy, Stuhlinger noted. Even if a large "meteor" hit the ship, he wrote, "the total loss of one or two sub-units would mean only a minor reduction of the capacity of the power plant."

Stuhlinger rejected an "atomic pile" as a heat source; in addition to having a mass of "hundreds of tons," a reactor would emit harmful radiation that would demand heavy shielding and make in-flight repair difficult. He added, however, that "an atomic pile will be a very promising power source for an electrically propelled space ship as soon as the mass problem, the shielding problem, and the maintenance problem have been solved satisfactorily."

The third major part of Stuhlinger's ship, the ion drive, would consist of many clustered thrust chambers. Within each, electricity from the solar-electric power system would ionize cesium or rubidium vapor using heated platinum grids and paired positive and negative electrodes. The cesium or rubidium ions would then depart the chamber through an opening at a large fraction of the speed of light to push the ship through space.

Stuhlinger wrote that cesium would be a more efficient propellant than rubidium. A cesium-fueled ship would need only 1833 thrust chambers to produce as much thrust as a rubidium-fueled ship with 2200 chambers. He noted, however, that cesium is "a rare element which might not be available in quantities as required for space ships."

Despite its large number of thrust chambers, Stuhlinger's ion drive would generate at most nine kilograms of thrust. This would, however, be applied continuously for long periods. Assuming no interference from planetary or solar gravity, Stuhlinger's ship could in a year travel 183 million kilometers in a straight line and reach a velocity of 12 kilometers per second.

Stuhlinger calculated that his ship would need just 18.6 tons of rubidium to accelerate continuously for one year. Even with its elaborate solar-electric power and ion drive systems, his ship's mass would total just 280 tons. To reach the same 12-kilometer-per-second velocity, a chemical-propulsion Mars spaceship would need a mass of about 820 tons, most of which would comprise propellants. For his calculations, Stuhlinger assumed that the chemical ship's rocket motors would burn nitric acid oxidizer and hydrazine fuel. He also assumed that both the ion and chemical Mars ships would be assembled in Earth orbit from components launched atop chemical-propulsion cargo rockets; his ship's lesser mass meant that it would need about a third as many cargo launches for assembly as would its chemical counterpart.

An ion drive spaceship would, of course, not travel between Earth and Mars in a straight line; it would instead gradually spiral out of Earth orbit into solar orbit, follow a curved course around the Sun to Mars, capture into a distant Mars orbit, spiral gradually down to a low Mars parking orbit, spiral out of Mars orbit, follow a curved course around the Sun back to Earth, capture into distant Earth orbit, and gradually spiral down to low Earth parking orbit. Halfway to Mars and again halfway to Earth the ship would turn end for end to face its thrust chambers forward and begin a slow deceleration. Stuhlinger determined, nonetheless, that his low-thrust solar-electric ion drive spaceship could travel from Earth orbit to Mars orbit and back in just two or three years; that is, in approximately the same period of time that a high-thrust chemical spaceship would need.

Stuhlinger did not call his spaceship the Cosmic Butterfly; that name originated with Frank Tinsley (1899-1965), an artist, cartoonist, and author famed for his futuristic technical illustrations. Tinsley used the term "gigantic butterfly" in reference to Stuhlinger's design in a 1956 article in Modern Mechanix magazine. The illustration at the top of this blog post, which Tinsley painted in 1959 for an American Bosch Arma Corporation advertisement titled "Cosmic Butterfly," depicts a ship little different from Stuhlinger's 1954 design.

"Possibilities of Electrical Space Ship Propulsion," E. Stuhlinger, Bericht über den V Internationalen Astronautischen Kongreß, Frederich Hecht, editor, 1955, pp. 100-119; paper presented at the Fifth International Astronautical Congress in Innsbruck, Austria, August 5-7, 1954.

http://beyondapollo.blogspot.com/2009/09/twirling-ion-mars-ships-1963.html

http://beyondapollo.blogspot.com/2011/06/nerva-electric-mars-ship-1966.html

http://blog.modernmechanix.com/2007/12/04/flight-to-the-stars-on-sun-power/ (accessed 10/5/11).

Lunar Oasis (1989)

2011-10-03T21:18:00.000-07:00

Settlements on other worlds are a staple of science fiction and of speculative space planning. To date, however, serious work to develop the technologies and techniques that might make this dream a reality has been extremely limited in scope.

In a paper presented in October 1989 at the 40th Congress of the International Astronautical Federation, two veteran space scientists proposed to change that. Michael Duke, Chief of the Solar System Exploration Division at NASA's Johnson Space Center (JSC) in Houston, and John Niehoff of Science Applications International Corporation (SAIC) outlined a 10-year program aimed at establishing a self-sufficient science outpost that would serve as testbed for space settlements. Self-sufficiency would also reduce the logistics burden of building and maintaining the outpost.

Their Lunar Oasis plan drew upon hardware and mission design approaches developed in the 1987-1988 Lunar Base System Study (LBSS), which Eagle Engineering performed on contract to JSC (images above), as well as SAIC-supported lunar and Mars studies performed in the NASA Headquarters Office of Exploration (link below).

Duke and Niehoff estimated that Lunar Oasis would have about four times the "magnitude" of the Apollo lunar program. They chose the moon over Mars as the site of their pioneering outpost because the former is relatively close at hand, permitting rescue of crews by spacecraft sent from Earth in the event of calamity.

Establishing a permanent outpost on the moon would, they wrote, involve technologies that were "not traditional in the space program" and were "better understood by. . .construction, chemical processing, agriculture, and other industries." They called for studies that would allow "experienced aerospace engineers and technical experts in a broad range of process industries to work together toward benchtop and pilot-scale plants. . ." They added that "[m]ost of this [work] can be carried out on Earth in a one-g[ravity] environment, which means that highly relevant research and development can be initiated soon."

In Duke and Niehoff's program, three missions would reach the moon every year for a decade. Every third mission would carry astronauts. Piloted landers would deliver 14 tons of cargo to the lunar surface while automated cargo landers would deliver 20 tons. Over the course of its first decade, 594 tons of equipment and supplies would reach Lunar Oasis.

Science equipment, which would generally be small and of relatively low mass, would be included as secondary payloads on most flights. Duke and Niehoff envisioned that, by the end of its first decade, Lunar Oasis would include a stock of geological field tools, an astrophysical/solar/terrestrial observatory, petrological and biological analysis laboratories, animal and plant experiment facilities, and surface-emplaced geological and geophysical experiment devices. In addition to serving the research needs of scientists, these science facilities would support self-sufficiency and long-term lunar occupancy. The animal and plant experiment facilities would, for example, generate data on the effects of reduced gravity on Earth life, while geological tools would enable Lunar Oasis crews to prospect for useful minerals.

Lunar Oasis development would proceed through three phases, though the program might be truncated if necessary; for example, if biomedical data indicated that astronauts could not survive for long periods in lunar gravity. The first phase, the Oasis Phase, would last about three years. Mission 1 would see an automated lander deliver a Space Station-derived construction module with a self-contained life support system. Four months later, a second automated lander would deliver construction machinery, a temporary power system, navigational aids, and supplies. Mission 3, the first piloted flight of Duke and Niehoff's program, would see a four-person sortie crew arrive for a four-month stay. The astronauts would inspect the Lunar Oasis site and position and activate the construction module.

The second year of the Oasis Phase would begin with Mission 4, an automated flight that would deliver supplies for the second Lunar Oasis crew. Mission 5 would deliver a nuclear power system and a facility for extracting volatiles (oxygen, carbon dioxide, and hydrogen) from lunar materials. Mission 6, the third flight of Year 2, would see six astronauts arrive for a one-year stay at the Lunar Oasis site, along with a cargo of tools, communications equipment, and a repair/maintenance system ("shop").

Mission 7 would kick off the third and final year of the Oasis Phase by delivering a 10-person inflatable habitat, which the Mission 6 crew would then assemble and pressurize. The hard-walled construction module delivered during Mission 1 would become a "safe haven" in the event of inflatable habitat failure. This approach was taken directly from LBSS. A closed-loop life support system capable of producing 95% of the food needed by a 10-person crew would then arrive on the Mission 8 cargo lander. The third piloted flight of the Lunar Oasis program, Mission 9, would deliver a 10-person crew for a one-year stay and a pressurized rover. The six-person crew would then return to Earth.

The second phase of the Lunar Oasis program, the Consolidation Phase, would last about seven years and include 22 flights. The first flight of the new phase, Mission 10 at the start of Year 4, would deliver a second nuclear power/volatiles extraction module. Mission 11 would deliver supplies and space suit systems. Mission 12 would see 10 more astronauts arrive, spelling the crew delivered on Mission 9 a year earlier. Barring catastrophe, they would remain on the moon for two years.

The Year 5 cargo missions would lay the groundwork for a lunar population explosion. Mission 13 would deliver a second inflatable habitat, providing additional redundant living space, and Mission 14 would add a second closed-loop life support system, providing additional redundant life support. On Mission 15, 10 more astronauts would arrive for a two-year stay, bringing the Lunar Oasis population to 20.

Lunar Oasis cargo deliveries in Years 6 through 11 would emphasize industrial development and extended stay times. Mission 16 would deliver augmentation equipment for the volatiles extraction facility, doubling its output, while Mission 17 would deliver a one-megawatt nuclear power plant, ensuring adequate electricity for industrial expansion. Mission 18 would see 10 astronauts arrive for a two-year stay. They would replace the Mission 12 crew. Year 7's two cargo missions would deliver an industrial module and a metal manufacturing facility, and its crew mission would deliver 10 astronauts for a three-year stay. They would replace the Mission 15 crew.

A concrete production facility would arrive on the Mission 22 cargo lander at the start of Year 8, followed by a third inflatable habitat on Mission 23 and 10 astronauts slated for a three-year stay on Mission 24. The latter would replace the Mission 18 crew. A second one-megawatt nuclear power system would arrive on Mission 25 at the start of Year 9, followed by a third closed-loop life support system. Ten more astronauts would arrive on Mission 27 for a three-year stay, boosting the moon's population to 30. Year 10 of the Lunar Oasis program would see the arrival of a second industrial module, solar cell production equipment, and (on Mission 30) 10 astronauts to replace the Mission 21 crew at the end of their pioneering three-year stay.

At the start of Year 11, Mission 31 would deliver a cargo of solar cell production equipment, moving the Lunar Oasis program into its open-ended third phase. In the Utilization Phase, Lunar Oasis would be capable of using lunar materials to spawn daughter habitats. The outpost would be equipped so that lunar resources could provide all life support needs and crew stays could last many years. "[I]f necessary," Duke and Niehoff wrote, Lunar Oasis "could survive for long periods of time with no resupply from Earth." It might also become a supplier of liquid oxygen and liquid hydrogen chemical propellants to spacecraft operating throughout cislunar space.

Duke and Niehoff proposed that Lunar Oasis be established at the Apollo 17 site at Taurus-Littrow, though they acknowledged that "any mare site would appear to be a reasonable choice." They also suggested an alternate course following the Oasis phase, with "no additional facilities. . .emplaced, as the crew reactions are studied and their capabilities in the lunar environment are tested." This could, they wrote, "be consistent with a program that changes emphasis at an early stage to the exploration of Mars."

"Lunar Oasis," IAF-89-717, Michael Duke and John Niehoff; paper presented at the 40th Congress of the International Astronautical Federation, October 7-12, 1989, Malaga, Spain.

http://beyondapollo.blogspot.com/2010/10/beyoind-earths-boundaries-1988.html

Harold Urey's lunar landing sites (1961)

2011-09-30T10:45:00.000-07:00

Harold Clayton Urey (bottom image above) was born in the small town of Walkerton, Indiana, on April 29, 1893. He taught school in Indiana and Montana, then earned Bachelor's degrees in Biology and Chemistry from the University of Montana. After a stint at a chemical plant in Philadelphia, he earned a PhD in Chemistry at the University of California at Berkeley in 1923. Following a fellowship in theoretical physics at the Bohr Institute in Copenhagen, he joined the Chemistry faculty at Johns Hopkins University in Baltimore, then moved to Columbia University in New York. On Thanksgiving Day in 1931, Urey discovered the hydrogen isotope deuterium, a feat which earned him the Nobel Prize in Chemistry in 1934.

Urey left Columbia for the University of Chicago in 1945. While in Chicago, he read Ralph Baldwin's 1949 book The Face of the Moon, which made the case for the impact hypothesis; that is, that the moon's many craters are not volcanic calderas, as was widely believed, but are instead scars left by asteroid impacts. The book changed Urey's professional life.

In 1952, Urey published The Planets, which launched modern lunar and planetary studies and the science of geochemistry as applied to extraterrestrial bodies. He christened this new discipline "cosmochemistry."

In his book, Urey espoused the "cold moon" theory; that is, that the moon is a primitive body that never became hot enough internally for its rocks to melt. Earth's natural satellite, he argued, was little changed from the time it formed. If humans one day could collect a piece of the moon, it followed, then they would have in hand a "Rosetta Stone" for deciphering the Solar System's early history.

What turned out to be the first steps toward lunar sample return occurred shortly after Urey's book saw print. In late July 1955, the U.S. announced that it would launch a civilian scientific Earth satellite during the International Geophysical Year (IGY), an 18-month world-wide science campaign that would begin on July 1, 1957. A little more than a month later, in early September 1955, the Soviet Union announced that it, too, would launch a satellite into Earth orbit.

President Dwight Eisenhower had little enthusiasm for rockets and satellites except insofar as they had defense applications. The U.S. IGY satellite, though civilian in nature, received his support because it had a hidden military agenda. It was intended to assert the international legal principle of the "Freedom of Space," which was meant to be analogous to the long-established principle of the Freedom of the Seas. The new principle would, Eisenhower hoped, quell Soviet protests when the U.S. began to launch surveillance satellites into orbits that would carry them over Soviet territory.

The Eisenhower Administration believed at first that the Soviet Union did the U.S. a "good turn" by launching Sputnik 1, the first Earth satellite, on October 4, 1957. The Soviet satellite, which passed over U.S. territory several times each day, made unnecessary American assertion of the Freedom of Space principle.

Sputnik 1 soon turned into a liability for the Eisenhower Administration, however. Eisenhower tried to downplay its significance, but neither an American public fearful of apparent Soviet technological superiority nor Democratic Senate Majority Leader Lyndon B. Johnson would stand for it.

One result of Sputnik 1 was the creation of the civilian National Aeronautics and Space Administration (NASA), which opened its doors on October 1, 1958. By then, both U.S. and Soviet rocketeers had begun to launch small probes toward the moon.

By all accounts, Urey was a generous man. He had, for example, shared credit for his deuterium discovery with the scientist who manufactured the five liters of liquid hydrogen he had used in his analysis.

He was also humble, and thus open to the possibility that his theories might be proven wrong. At the Lunar and Planetary Exploration Colloquium held at the Jet Propulsion Laboratory on October 29, 1958, he predicted that new lunar discoveries would give him a "very red face" in only a few years; that is, that spacecraft would soon collect data that would disprove many of his lunar theories. "Nature can always be more complicated than we imagine," he added.

During 1958, Urey retired from the University of Chicago and went to work at the University of California-San Diego. It was there, in November 1958, that Urey met with newly hired NASA scientist Robert Jastrow, whom he quickly converted to the cause of lunar exploration.

The following month, Urey and Jastrow met with NASA Deputy Director for Space Flight Programs Homer Newell at NASA Headquarters in Washington, DC. At the time, scientists interested in space physics - the study of particles and fields in space - dominated NASA space science. Urey and Jastrow sought to convince Newell that the NASA should apply its scientific energies to the exploration of the moon.

On February 5, 1959, the NASA Working Group on Lunar Exploration, chaired by Jastrow, met for the first time. Urey was an enthusiastic member. He also became a founding member of the influential National Academy of Science Space Science Board, which displayed its enthusiasm for lunar exploration by forming a "Lunar Committee." The group strongly supported President John F. Kennedy's May 25, 1961 call for a man on the moon by 1970.

Three weeks after Kennedy's "moon speech," Urey responded to an informal request from Newell that he recommend landing sites on the moon. In a June 19, 1961 letter, the polymath Nobel Laureate told Newell that "we should attempt to. . .get as great a variety of objectives as possible in as few landings as possible." He then listed six classes of sites which he felt should be explored.

The first took in sites at high latitudes (that is, close to the lunar poles) (1 on the top image above). Urey explained that Harrison Brown, a fellow member of the Working Group on Lunar Exploration, had "presented evidence that water may exist close to the surface in certain high latitude areas." This was, of course, in keeping with Urey's "cold moon" hypothesis.

Urey then called for landings on two of the lunar maria ("seas"), the smooth, relatively dark-hued plains that mottle the moon's Earth-facing Nearside hemisphere. One of these, he explained, should be "of the deep type" - that is, it should be an obvious giant impact basin such as "the great collision area just before Sinus Iridium in Mare Imbrium" (2) or Mare Serenitatis (3). Seismic instruments emplaced on a deep mare would, Urey believed, enable determination of the depth to which the giant impactors that formed them had penetrated the moon's crust.

The other mare landing should occur on a "shallow" mare, Urey wrote. In the shallow category he listed Oceanus Procellarum (4) and Mare Tranquillitatis (5), neither of which displays the distinctive round outline of Imbrium and Serenitatis. Urey told Newell that NASA would probably land first in Oceanus Procellarum in any case because it was a wide plain with few mountains or other obstructions to imperil descending spacecraft.

Next on Urey's wish list was the interior of a large impact crater. He suggested Alphonsus (6), an old crater partly filled with "gray material," in which Soviet scientist Nikolai Kozyrev claimed to have observed a short-lived white cloud in 1958. Urey also noted that geologist Eugene Shoemaker, founder and first chief of the U.S. Geological Survey's Branch of Astrogeology in Menlo Park, California, was busy studying the young crater Copernicus (7) in "very great detail," and that his work might pave the way for a landing there.

Fourth on Urey's list was one of the "great wrinkles in the maria." He told Newell that the wrinkle ridges, as they are known, might be places where water had escaped from the moon's cold interior. He added that Gerard Kuiper, founder of the Lunar and Planetary Laboratory in Tucson, Arizona, had observed deposits of white material atop the ridges. Urey interpreted these to be salts left behind as water boiled away in the lunar vacuum.

A moon lander dispatched to Mare Imbrium near Sinus Iridium could, Urey added, explore both a deep mare and prominent wrinkle ridges (8). Similarly, a landing near Copernicus could explore both the great crater and nearby "little volcano-like things" (9) that Urey felt were related to the wrinkle ridges.

Number five on Urey's list was a mountainous area. His chief candidate was the Haemus Mountains on the south edge of Mare Serenitatis (10), which he believed constituted a mass of material blasted out during the formation of Mare Imbrium.

Finally, Urey listed features that were of interest to him personally. These included an unusual dark gray line in Mare Serenitatis, which he had theorized in the early 1950s was a streak of carbon-rich material similar to that found in primitive carbonaceous chondrite meteorites (11). He also suggested the Aristarchus-Herodotus region (12), which Kozyrev had found to be "luminous," and Lacus Mortis (13), which Urey believed was a graben; that is, a sunken block of lunar crust.

Urey ended his letter by asking Newell to share with him any landing site suggestions he received from other scientists. He argued that site selection was an important matter that "should be considered by many of us."

In his reply of June 29, 1961, Newell told Urey that he had forwarded his suggestions to NASA's Office of Lunar and Planetary Programs and to "the special study groups who have been working out plans for the manned lunar landing" (bottom link below). Newell also urged Urey to share with him "any ideas that the Lunar Committee of the Academy's Space Science Board might have."

Urey remained active in lunar exploration throughout the 1960s. He participated in Ranger (1961-1965) and Surveyor (1966-1968) automated missions, as well as the manned Apollo 11 (July 1969) and Apollo 12 (November 1969) missions, which sampled Mare Tranquillitatis and Oceanus Procellarum, respectively. As he predicted, he had occasion to become red in the face: the moon, the Apollo samples and surface experiments showed, was molten during its first 1.5 billion years of existence, probably experienced surface volcanism as recently as 1 billion years ago, and today has a molten inner mantle and outer core.

Urey continued his lunar studies until well into his 80s. Among his last scientific papers was one on lunar iron chemistry published in 1977. He died in La Jolla, California, on January 5, 1981.

Letter, Harold C. Urey to Dr. Homer E. Newell, Deputy Director, Space Flight Programs, NASA Headquarters, June 19, 1961.

Letter, Homer E. Newell to Dr. Harold C. Urey, School of Science and Engineering, University of California-San Diego, June 29, 1961.

"The Chemistry of the Moon," Harold C. Urey, Proceedings of the Lunar and Planetary Exploration Colloquium, October 29, 1958, Publication 513W3, Vol. 1, No. 3, Missile Division, North American Aviation, 1958.

"Harold Urey and the Moon," Homer E. Newell, The Moon, Volume 7, pp. 1-5, 1973 (http://adsabs.harvard.edu/abs/1973Moon....7....1N) (accessed 10/1/2011).

NASA's Origins and the Dawn of the Space Age, Monographs in Aerospace History #10, David S. F. Portree, NASA History Division, September 1998 (http://history.nasa.gov/monograph10/) (accessed 10/1/2011).

http://beyondapollo.blogspot.com/2011/05/apollo-science-sites-1963.html

Engineer Special Study of the Surface of the Moon (1960, 1961)

2011-09-26T17:51:00.000-07:00

The race to the moon began on August 17, 1958, and the Soviet Union won. This isn't the opening line of an alternate history story; rather, it is an acknowledgment that more than one moon race took place. The first, with the goal of launching a small automated spacecraft to the moon, began with the liftoff of the Able 1 lunar orbiter, a 38-kilogram U.S. Air Force (USAF) probe. (It was later redesignated Pioneer 0.) Just 77 seconds after launch from Cape Canaveral, Florida, Able 1's first-stage Thor rocket exploded, ending the world's first attempted lunar mission.

A month later, on September 23, 1958, the Soviet Union joined the race. A spherical Luna probe intended to impact the moon fell victim to the failure of its upgraded R-7 booster rocket just 93 seconds after liftoff from Baikonur Cosmodrome in central Asia.

On October 11, 1958, USAF launched Able 2, a near-copy of Able 1. It was the first lunar launch conducted under NASA auspices. The civilian space agency had opened its doors on October 1, 1958. NASA absorbed most Department of Defense space projects, though in practice the USAF and Army continued to carry out missions while interagency relations and lines of command became defined. Able 2, later redesignated Pioneer 1, burned up in Earth's atmosphere on October 13, after its Able second stage shut down early, placing it on an elliptical path that took it about a third of the way to the moon. The Soviets launched their second Luna moon impactor just 16 hours after the U.S. launched Able 2. The Luna's upgraded R-7 launch vehicle exploded 104 seconds after liftoff.

And so it went, with launches from Florida and Kazakhstan alternating and failing. The Pioneer 2 lunar orbiter (November 8, 1958) and another Luna impactor (December 4, 1958) fell victim to premature launch vehicle shutdowns. Pioneer 3 (December 6-7, 1958), the first NASA/Army moon probe, was launched on an Army Juno II, not a USAF Thor-Able, but performed much as had Pioneer 1.

On January 3, 1959, the Soviet Union snatched victory from the jaws of defeat. Their Luna 1 impactor missed the moon by 6400 kilometers, and so failed to accomplish its mission. It sailed on, however, becoming the first human-made object to orbit the Sun. The Soviets nicknamed it Mechta ("dream"). The Army launched the Pioneer 4 lunar flyby spacecraft two months later (March 3, 1959). It failed to return images of the moon, but repeated Mechta's feat.

Another unnumbered Luna impactor fell victim to an R-7 failure on June 18, 1959. Then, on September 14, 1959, on their sixth attempt, Soviet rocketeers succeeded in striking the moon with the Luna 2 impactor. The probe struck near the center of the moon's Nearside, the hemisphere that faces the Earth. Three weeks later (October 6, 1959), Luna 3 flew 7900 kilometers over the moon's south pole and imaged the hidden Farside hemisphere.

In a last-ditch effort to steal the Soviet Union's thunder, the USAF and NASA decided to give a planned Pioneer Venus orbiter a new mission: orbit and photograph the moon at close range. Its mission ended 104 seconds after liftoff on November 26, 1959, when its Atlas-Able launcher lost its streamlined launch shroud and tumbled out of control.

As the first moon race ended in Soviet victory, pressure built in the U.S. for a rematch. Though President Dwight Eisenhower had made it clear that the Department of Defense branch services should concentrate on space and rocket projects with immediate military applications, the moon still beckoned to Army and USAF rocketeers.

Even after the creation of NASA, the Army and USAF studied lunar surface bases. The Army Ballistic Missile Agency studied Project Horizon, a lunar fort, while the USAF worked with contractors on the SR-183 Lunar Observatory project. LUNEX was a USAF study of an early manned lunar expedition. The USAF also began lunar mapping using Earth-based telescopes.

The first attempt to map lunar features for scientific and engineering purposes did not, however, originate within the Defense Department. It was begun instead by Arnold Mason of the U.S. Geological Survey (USGS) Military Geology Branch in Washington, DC. According to Don Wilhelms, writing in his 1993 memoir To a Rocky Moon, the peripatetic Mason became interested in lunar geology after the October 4, 1957 launch of Sputnik 1. Mason's boss, Frank Whitmore, soon got caught up in his enthusiasm. Whitmore, incidentally, served as Secretary of the Geological Society of Washington.

Early in 1959 - soon after Luna 1 - Mason proposed to carry out an analysis of the moon's terrains to determine their suitability for spacecraft landings, travel on foot and by rover, and base construction. With Whitmore's blessing, he enlisted Robert Hackman and Annabel Brown Olson of the USGS Photogeology Branch in his project. Mason became project chief, Hackman became Mason's co-author, and Olson (who, according to Wilhelms, received insufficient credit for her labors) assisted Hackman. At first, they had available only meager USGS funds. Soon after Luna 2 and Luna 3, however, the Army Corps of Engineers funded their study.

Mason and Hackman's assessment took in only the Nearside. They based their analysis on photographic plates from large telescopes on Earth, which under the best viewing conditions could (they estimated) reveal features on the moon no smaller than about a mile across. In fact, features 10 miles wide were barely discernable in most of the photographic images they used.

Their work soon drew in as consultants lunar experts Gerard Kuiper (McDonald Observatory), Eugene Shoemaker (USGS Menlo Park), and Robert Dietz (Naval Electronics Laboratory). All three supported the impact hypothesis, which stated that most of the moon's craters are asteroid impact scars; not, as some believed, volcanic calderas. At the time, planetary astronomer Kuiper was hard at work on a USAF-funded lunar photographic atlas; Mason and Hackman would use it near the end of their study. Shoemaker, meanwhile, was busy refining a prototype lunar geologic map of the region containing the large, relatively young crater Copernicus; Hackman would later assist him with identification of lineaments in the Copernicus region.

The Army Corps of Engineers published the first edition of Mason and Hackman's four-sheet "Engineer Special Study of the Surface of the Moon" map set in July 1960. The USGS published a second edition with "minor revisions" the following year.

The "Engineer Special Study" was significant in part because its Sheet 1, titled "Generalized Photogeologic Map" (top image above), was the first major lunar map to show stratigraphic relationships: that is, it attempted to display the chronological order of the formation of the moon's surface features. Mason and Hackman's stratigraphic system centered on the formation of the maria (Latin for "seas"), the relatively smooth, dark-hued plains that mottle the Nearside. They make up about 20% of the moon's surface.

Mason and Hackman colored orange the heavily cratered, light-colored "pre-maria" terrain; that is, landforms that they believed were already in place when the maria formed. They colored maria yellow, while green indicated "post-maria" features; mainly young asteroid impact craters, but also features that they interpreted as being of recent volcanic origin. They used black dots to mark what they identified as volcanic cones and domes and thin black lines to mark what they thought were tectonic faults.

As might be expected, given the quality of the data they had available and the primitive state of lunar science, many of Mason and Hackman's geologic interpretations are known now to be incorrect. Nearly all of the features they identified as volcanic in origin, for example, turned out to be products of impact processes.

Their stratigraphic map, though pioneering, was too simplistic to accurately portray the moon's history. The maria basins formed at different times during the first few hundred million years of lunar history, so features associated with them often overlap. An impact crater blasted into an older mare would, for example, become a pre-maria landform by Mason and Hackman's reckoning if it became engulfed in ejecta and lava from a later basin-forming giant impact. In addition, some prominent lunar features identified as pre-maria (the Apennine Mountains, for example) should have been represented by a fourth color to signify that they are non-maria features created by the same giant asteroid impacts that excavated the maria basins.

By contrast, Shoemaker's nearly contemporaneous prototype Copernicus geology map, printed in small quantity by the USAF Aeronautical Chart and Information Center in April 1961, identified five stratigraphic "systems." From oldest to youngest, these were the Pre-Imbrian, Imbrian, Procellarian, Erastothenian, and Copernican systems. Even this would turn out to be simplistic, however, once robot and human explorers began to provide lunar geologists with close-up images of the moon's complex terrain.

On Sheet 2 of the "Engineer Special Study," titled "Lunar Rays," Mason and Hackman plotted the source craters and extent of the moon's most prominent ray systems (middle image above). They correctly identified the light-hued rays as ejecta blasted out from young asteroid impact craters.

Mason and Hackman's Sheet 3, titled "Physiographic Divisions of the Moon," was their most ambitious (bottom image above). In it, they applied photogeologic principles pioneered on Earth to identify more than 70 different lunar terrain units.

Details of the three "Engineer Special Study" map sheets. All three closeups take in an area of near-equatorial western Oceanus Procellarum centered just east of Copernicus crater.

Sheets 1 through 3 laid the groundwork (literally) for Sheet 4, on which Mason assessed in writing the landing, travel, and construction conditions in each of the physiographic regions on Sheet 3. What follows are summaries of his assessments for several regions that have been visited by spacecraft.

Luna 2 struck the southern flank of Autolycus crater in the northern part of Mason and Hackman's Apennines Region. According to Mason and Hackman's analysis, Autolycus is a post-maria impact crater, only lightly rayed, on the western edge of Mare Imbrium, in the extensive Mid Lunar Lowlands. Mason wrote that the surface in the Apennines Region is rough and blocky, so landings there would be very difficult. Movement in the region would, he judged, be the "most difficult on the moon's surface, and possible only by carefully selected routes." Construction would be "very difficult because of blocky material and steep slopes."

Luna 2 was not designed to return images as it plunged toward the moon; however, the Apollo 15 Lunar Module Falcon landed west of the Luna 2 impact site on July 30, 1971. Astronauts David Scott and James Irwin found the area to be cratered and rolling, but difficult neither to land on nor to navigate on foot and by rover. The surface material was loose to a depth of many meters. The nearby Apennine Mountains, which Mason and Hackman had envisioned as steep and jagged, turned out to have been rounded and partly leveled by micrometeoroid impacts over the nearly four billion years since their formation.

Apollo 15 Lunar Module Falcon and the Apennine Mountains.

NASA's Ranger 7 probe was designed to return images of the lunar surface as it fell toward destructive impact. On July 31, 1964, Ranger 7 returned more than 4300 photos of the area between Oceanus Procellarum and Mare Nubium. Mason and Hackman called the area containing Ranger 7's impact site the Riphaeus Section. It was a lowland maria divided by the highland Riphaeus Mountains. Mason judged that landing and movement would be "generally easy" if blocky isolated pre-maria highland areas and post-maria craters could be avoided.

Construction, on the other hand, would be a challenge in the Riphaeus Section. Mason expected that, under a thin layer of loose debris, lunar base builders would find basaltic rock hard enough to prevent boring and excavation. Whereas in the Apennines Region he advised lunar base builders to avoid craters and their blocky surroundings, in the Riphaeus Section such asteroid-shattered areas would probably be the only places where digging could occur. This applied to other maria lowlands as well.

Scientists examining Ranger 7 images found that its impact area was cratered down to the scale of inches; however, the craters were almost all eroded, with smooth floors and rims and few large rocks. Micrometeoroids had been whittling away at the terrain in the Riphaeus Section for a very long time. In tribute to Ranger 7, lunar mappers named the area where it impacted Mare Cognitum, which means "Known Sea."

Surveyor 7, the last of its series of soft landers, alighted gently on the northern flank of Tycho crater (image below) on January 10, 1968. Mason and Hackman identified the area containing post-maria Tycho as the pre-maria Macrocrater Province. Tycho, they wrote, spanned 54 miles from rim to rim. The crater's floor was 12,000 feet below its rim, which stood 7900 feet above the surrounding terrain. They noted that Tycho was the moon's most prominent ray crater, with bright streaks extending up to 500 miles plainly visible to the unaided eye at full moon.

Mason judged that landing and movement would be difficult near Tycho. The latter would be possible, however, if a safe route could be selected in advance. Construction would be difficult because of the many large blocks embedded throughout the area.

Surveyor 7 landed blind on Tycho's flank; that is, it included no hazard-avoidance system. Through its scanning camera scientists saw that the area was indeed rougher than those that previous Surveyors had explored. They saw loose rocks, boulders, relatively steep slopes, apparent bedrock outcrops, and odd "lakes" of dark gray material, possibly cinders laid down by recent volcanism or rock melted by the colossal energies of the Tycho impact. Some of these features could have destroyed Surveyor 7 had it landed on them.

Panorama of Tycho crater's north rim from Surveyor 7.

In general, however, Tycho, like the Riphaeus Section and the Apennines Region, was not as rugged as Mason had predicted. In fact, after Surveyor 7, some felt that Tycho's flank was smooth and level enough for Apollo astronauts to visit. A 1969 study based on Surveyor 7 images determined that it was too rough for a manned rover, however.

In early December 1960, Mason and Hackman attended the International Astronomical Union's First Lunar Symposium at Pulkovo Observatory in Leningrad. The meeting was held in the Soviet Union in deference to that country's demonstrated lead in lunar exploration. They displayed the Army Corps of Engineers edition of the "Engineer Special Study." Upon his return from the historic symposium, Mason presented an informal report on the trip to the January 1961 meeting of the Geological Society of Washington. Mason's boss Whitmore briefly summarized his report in the meeting minutes.

Hackman appeared as co-author on Shoemaker's April 1961 prototype Copernicus geologic map. Copernicus mapping then stalled for several years because Shoemaker had new responsibilities. He had succeeded in launching the NASA-supported Astrogeology Studies Project at USGS Menlo Park, near San Francisco, in August 1960; this became the NASA-supported USGS Branch of Astrogeology in September 1961. In addition, he was busy publishing ground-breaking papers on lunar cratering dynamics and lunar and terrestrial geologic timescales.

In July 1961, Hackman submitted for review what became after the "Engineer Special Study" the second published USGS lunar map: a geologic study of the Kepler region based on Shoemaker's lunar geologic mapping conventions and five-system lunar stratigraphic column. The Kepler map, published in 1962 under the auspices of the Branch of Astrogeology, was the first NASA-funded USGS lunar map to be published.

Eleven months after the Pulkovo symposium, in November 1961, Whitmore had the sad duty of informing the Geological Society of Washington of Mason's untimely death. The pioneering lunar mapper had taken his own life on October 31, 1961. He was 54 years old.

In his memoir, Wilhelms wrote that Mason committed suicide "for reasons that are not entirely clear and are undoubtedly complex, but which seem to have included non-recognition for his original and ardent pioneering of lunar studies for the U.S. Geological Survey." Pulkovo had marked the high point of Mason's lunar career: after that, Shoemaker's new astrogeology program increasingly sidelined USGS lunar studies in Washington, DC.

Hackman's involvement in lunar geologic mapping was by then also drawing to a close. His steadfast refusal to leave the Washington area proved to be career limiting. Shoemaker transplanted the Branch of Astrogeology from Menlo Park to the small town of Flagstaff, Arizona, during 1963, and soon the name "Flagstaff" became synonymous with lunar and planetary mapping. Hackman completed one more map for the Branch of Astrogeology - a geologic map of the moon's Apennines region, which was published in 1966 - but his pioneering contributions to lunar geologic mapping ceased with publication of the Kepler map.

Although the "Engineer Special Study" remained relatively obscure - and became even more so after data from lunar spacecraft rendered much of it obsolete - it did manage to earn a small place in popular culture. Chapter 12 of Arthur C. Clarke's 1968 novel 2001: A Space Odyssey, titled "Journey by Earthlight," begins with a description of the Macrocrater Province and the crater Tycho extracted from Mason's Sheet 4 of the "Engineer Special Study."

Engineer Special Study of the Surface of the Moon, Robert J. Hackman and Arnold C. Mason, Army Map Service, Corps of Engineers, July 1960.

Engineer Special Study of the Surface of the Moon, Miscellaneous Geologic Investigations Map I-351, Robert J. Hackman and Arnold C. Mason, U.S. Geological Survey, Washington, DC, 1961.

Memorial to Arnold Caverly Mason (1906-1961), H. Foster, Geological Society of America Bulletin, Vol. 73, August 1962, pp. 87-90.

To A Rocky Moon: A Geologist's History of Lunar Exploration, Don E. Wilhems, The University of Arizona Press, 1993, pp. 37-42 (http://www.lpi.usra.edu/publications/books/rockyMoon/) (accessed 9/26/11).

http://www.lpi.usra.edu/resources/mapcatalog/ESS/ (accessed 9/26/11)

http://www.gswweb.org/minutes/GSW1961.htm (accessed 9/26/11)

http://beyondapollo.blogspot.com/2010/04/mission-to-tycho-1969.html

http://beyondapollo.blogspot.com/2011/08/lunex-1961.html

Blueprint for 1970s planetary exploration (1968)

2011-09-21T20:14:00.002-07:00

In August 1967, Congress refused to support NASA's plans for the 1970s. Citing fiscal restraint, it rejected piloted Mars/Venus flyby missions in 1975 and 1977 and canceled the Voyager Mars/Venus program, NASA's only robotic program planned for the decade. The Apollo Applications Program, which had been tapped as the agency's main 1970s piloted program, suffered a cut of half a billion dollars.

This assault on NASA's future was partly the result of the deadly Apollo 1 fire (January 1967), which undermined confidence in the U.S. civilian space agency. A growing Federal budget deficit fueled by the escalating war in Indochina also played a role.

NASA's detractors argued that piloted flybys, Voyager, and AAP were stealthy steps toward an early commitment to costly piloted Mars landing missions. Others complained that NASA's program lacked "balance." This criticism meant different things coming from different people. For some, it meant that NASA gave to astronauts tasks that robots could perform more cheaply and with less risk; for others, it meant that NASA placed too much emphasis on the moon and Mars and not enough on the rest of the Solar System.

NASA officials met with Congressional leaders in late September 1967 to try to negotiate a replacement for Voyager. NASA Administrator James Webb and others reminded them that, with Voyager gone, the U.S. would have no robotic planetary program after the Mariner 1969 Mars flyby missions, leaving to the Soviet Union the prestige benefits of Solar System exploration. Congress relented partially, agreeing to initiate funding in Fiscal Year 1969 for a pair of Mariner 1971 Mars orbiters and a pair of Mariner-based Mars orbiter/lander missions in 1973.

This concession, combined with the successful first unmanned flight of the Apollo Saturn V rocket (Apollo 4) in early November 1967, encouraged some within NASA to look for ways of accommodating the detractors while continuing planning for piloted Mars missions. In late November-early December 1967, NASA's Office of Manned Space Flight asked J. Downs and W. Thompson of Bellcomm, NASA's Apollo planning contractor, to develop a plan for a feasible "balanced manned and unmanned planetary program through 1980." Their blueprint, completed in late February 1968, included Mariner-based robotic Mars and Venus spacecraft as precursors to piloted Mars and Venus flybys and robotic pure science missions to Mercury, Jupiter, Saturn, and beyond.

Downs and Thompson kicked off their program with a Mariner Venus flyby in 1970. The spacecraft, which would be built from "spare parts" left over from Mariner Mars 1969, might use Venus's gravity to speed it toward a flyby of the planet Mercury. The next year, NASA would launch the Mariner Mars orbiters it had discussed with Congress. The Bellcomm engineers called for them to be launched on Titan III-C rockets so that they could each carry to Mars a 350-pound rough-landing probe bearing 13 pounds of instrumentation. The probes would begin the in-situ search for life on Mars.

Titan III-C rocket launch.

Next up, in 1972, a Titan III-C would launch a Venus orbiter with an atmosphere probe. In keeping with NASA's agreement with Congress, two more Titan III-C rockets would launch one Mars orbiter with probe each in 1973. Downs and Thompson expected that the 1971 landing probe would have found life on Mars, so the instruments on the twin 1973 probes could focus on learning about that life. In addition to Mars, the orbiters would image Phobos and Deimos, the two small martian moons.

The year 1973 would also see a Mariner spacecraft fly past Venus and release a 600-pound probe designed to survive landing on the cloudy planet's harsh surface. With help from Venus's gravity, the Mariner would then fly past Mercury. Downs and Thompson noted that placing a spacecraft into orbit around Mercury would demand a great deal of energy (hence propellant), and advised that the decision about whether to fly a Mercury orbiter should be postponed until after the 1973 flyby. They also noted that the next Venus-Mercury flyby opportunity would not occur until 1982.

In 1974, NASA would expand its horizons to the stars by launching a 600-pound "Galactic Jupiter Probe" on an Atlas rocket with a Centaur upper stage. As envisioned by engineers at NASA's Goddard Space Flight Center in Maryland, the Galactic Jupiter probe would explore Jupiter and use a gravity assist from that giant planet to gain speed and bend its course. The spacecraft would climb above the plane of the ecliptic to explore interplanetary particles and fields and, ultimately, escape the Solar System entirely to wander derelict among the stars.

In the Downs-Thompson blueprint, 1975 was a busy year. A Mars orbiter more sophisticated than any launched before would dispatch a heavy probe to a site scientists had identified as exobiologically interesting based on Mariner Mars 1971 and 1973 data. A second Galactic Jupiter Probe would begin its journey to Jupiter and beyond, and NASA would launch two Venus orbiters, each bearing two rough-landing probes.

The year 1976 would see the first of four NASA missions to non-planetary Solar System bodies: an Atlas-Centaur would launch a Mariner past short-period Comet d'Arrest. In 1978, a Mariner would fly past the asteroid Icarus, and asteroid Eros would receive a Mariner in 1979. Finally, a Mariner launched on a Titan III-C/Centaur would fly past Comet Encke in 1980.

In 1977, NASA would launch a Venus orbiter with a high-resolution cloud-piercing radar and multiple atmosphere probes. The new-design Venus orbiter used in 1975 and 1977 would need a launch vehicle more powerful than the Titan III-C - possibly a reduced-capability Saturn V, Downs and Thompson wrote. The 1975 and 1977 Mars missions would also need this powerful rocket.

The 1977 Mars flight would serve as a dedicated precursor for the piloted Mars/Venus flyby mission scheduled for launch in 1978. Its landing probe would, for example, provide data on the topography of a landing site chosen for one of the piloted flyby spacecraft's large Mars Surface Sample Return (MSSR) probes.

The year 1977 would also see the first "Grand Tour" spacecraft leave Earth on a Titan III-C with a Centaur upper stage. The new-design 1000-pound spacecraft would fly past Jupiter and receive a gravity-assist "kick" to Saturn. The gravity-assist it would receive while exploring Saturn would speed it onward to mysterious Uranus, where a third gravity-assist would send it on to Neptune. The spacecraft would fly past the Solar System's most distant gas giant planet nine years after departing Earth. A second Grand Tour spacecraft would leave Earth in 1978.

Piloted Mars/Venus flyby spacecraft departs Earth orbit.
Also in 1978, NASA would launch the first of two piloted Mars/Venus flyby missions. Downs and Thompson wrote that the two piloted flyby missions would serve as precursors for a piloted Mars landing mission in 1984. The 1978 mission would fly past Venus in 1979, where the crew would release weather balloons and surface impactors. Later in the year, it would fly past Mars, releasing a small swarm of MSSR probes. These would land, collect Mars samples, and return them to the astronauts on the flyby spacecraft for immediate analysis. In 1981, the astronauts would fly past Venus a second time and return to Earth. The second piloted Venus/Mars/Venus flyby mission would depart Earth in 1981 and return home in 1983.

Minimum-energy launch opportunities are what they are, so it is not too surprising that NASA carried out missions resembling those in the Downs-Thompson blueprint. The 1971 Mariner Mars orbiters, for example, corresponded to the Mariner 9 mission, though the latter included no landing probe. (Mariner 8, the first of the intended pair of 1971 Mars orbiters, crashed in the Atlantic after its Atlas-Centaur launch vehicle failed.) The 1973 Mariner-based Mars orbiters and landers were named Viking, then funding cuts pushed their launch to 1975. NASA missed the 1970 Venus-Mercury opportunity, but launched Mariner 10 in 1973 (middle image above). It flew past Venus in February 1974, then past Mercury in March 1974, September 1974, and March 1975.

NASA launched its first Galactic Jupiter Probe two years early; Pioneer 10 left Earth in March 1972 and flew past Jupiter in December 1973 (bottom image above). Its twin, Pioneer 11, left Earth in April 1973, flew past Jupiter in December 1974, and flew past Saturn in September 1979. NASA cancelled the Grand Tour in 1972, but launched the Mariner-based Voyager 1 and 2 spacecraft in September 1977 and August 1977, respectively. Voyager 1 flew past Jupiter in March 1979 and Saturn in November 1979 (top image above). Voyager 2 flew past Jupiter in July 1979, Saturn in August 1981, Uranus in January 1986, and Neptune in August 1989.

NASA launched no piloted flyby in 1978; in fact, when that launch opportunity came and went no American astronauts had reached space since July 1975 (and none would again until April 1981). Instead, it launched the first U.S. Venus orbiter, Pioneer Venus 1 (May 1978), and Pioneer Venus 2 (August 1978), which carried a cluster of four Venus atmosphere entry probes (image below). Budget cuts and Space Shuttle problems meant that Pioneer Venus 2 was the last U.S. planetary probe to leave Earth for nearly 11 years.

A Feasible Planetary Exploration Program Through 1980 - Case 710, J. P. Downs and W. B. Thompson, Bellcomm, February 29, 1968.

Giotto II (1985)

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On the overcast morning of July 2, 1985, the eleventh Ariane 1 rocket launch took place at the Centre Spatial Guyanais in Kourou, French Guiana, an outpost of the European Community located a few degrees north of the equator on the northeast coast of South America (top image above). The last Ariane 1 to fly, it bore aloft Giotto, the first European Space Agency (ESA) interplanetary spacecraft (middle image above). Giotto's destination was Comet Halley.

A "dirty snowball" containing materials left over from the birth of the Solar System 4.6 billion years ago, Halley needs about 76 years to revolve around the Sun once. Its elongated orbit takes it as near to the Sun as the space between the orbits of Venus and Mercury and as far from the Sun as the cold emptiness beyond the orbit of Uranus.

Comet Halley has passed through the inner Solar System 42 times since its first recorded apparition. In 837, it passed just 5.1 million kilometers from Earth; during that apparition, its dust tail must have spanned nearly half the sky, and its bright coma - the roughly spherical dust and gas cloud surrounding its icy nucleus - may have been as large as the full moon. During its apparition of 1301, Italian artist Giotto di Bondone painted Comet Halley. The Giotto spacecraft was named for him.

The Ariane 1's third stage injected 980-kilogram Giotto into a 198.5-by-36,000-kilometer orbit about the Earth. Thirty-two hours after launch, as it completed its third orbit, flight controllers in Darmstadt in the Federal Republic of Germany commanded Giotto to ignite its French-built Mage solid-propellant rocket motor. The aft-pointing motor burned 374 kilograms of propellant in 55 seconds to inject the spinning 2.85-meter-tall, 1.85-meter-diameter spacecraft into orbit about the Sun.

Two months before Giotto's launch, Americans P. Tsou (Jet Propulsion Laboratory), D. Brownlee (University of Washington), and A. Albee (Caltech) proposed in a paper in the Journal of the British Interplanetary Society that a second Giotto mission be dispatched to fly close by one of 13 candidate comets between 1988 and 1994. The spacecraft, which they dubbed Giotto II, might launch on an Ariane 3 or in the payload bay of a Space Shuttle. Giotto II's "free-return" trajectory would take it as close as 80 kilometers from the target comet's nucleus, then would return it to Earth. Near the comet, Giotto II would expose sample collectors to the dusty cometary environment. Near Earth, it would eject a sample-return capsule based on the proven General Electric (GE) Satellite Recovery Vehicle (SRV) design. The capsule would enter Earth's atmosphere to deliver its precious cargo of comet dust to eager scientists.

Tsou, Brownlee, and Albee pointed out that the Mage solid-propellant motor was not required to boost Giotto into interplanetary space; that is, that the Ariane 1 could do the job itself. Giotto was, however, based on a British Aerospace-built Geos magnetospheric satellite design, which included the Mage motor. Re-testing the design without the motor would have cost time and money, so ESA elected to retain it for Giotto. After noting that the GE SRV could fit comfortably in the space reserved for the Mage, they proposed that the reentry capsule replace the motor in Giotto II.

Giotto included a "whipple bumper" on its aft end to protect it from hypervelocity dust impacts. During approach to Comet Halley, the spacecraft would turn the bumper in its direction of flight. The bumper comprised a one-millimeter-thick aluminum shield plate designed to break up, vaporize, and slow impactors, a 25-centimeter empty space, and a 12-millimeter-thick Kevlar sheet to halt the partially vaporized, partially fragmented impactors that penetrated the aluminum shield.

In the case of Comet Halley, dust would impact the bumper at up to 68 kilometers per second. Tsou, Brownlee, and Albee noted that the 13 candidate Giotto II comets were all less dusty and would have lower dust impact velocities than Halley. Because of this, Giotto II would need less shielding than Giotto.

Impacting dust would nonetheless create challenges for Giotto II. Tsou, Brownlee, and Albee devoted much attention in their paper to how the spacecraft might successfully capture dust for return to Earth. One capture system, a variant of the whipple bumper, would use a shield made from ultrapure material to vaporize and slow impacting dust particles. The vapor from the impactor and the impacted part of the bumper would then be captured as it condensed. Scientists would disregard the bumper material when they analyzed the condensate.

Tsou, Brownlee, and Albee then noted that thermal blankets returned from the Earth-orbiting Solar Maximum Mission satellite had shown that intact capture of high-velocity particles was possible. The multilayer Kapton/Mylar blankets collected hundreds of intact meteoroids and human-made orbital debris particles. They described preliminary experiments in which "underdense materials" (polymer foams and fiber felts) were subjected to high-velocity impacts by meteoroid and glass fragments fired from gas guns. The experiments suggested that such materials could indeed capture at least partially intact dust particles.

Giotto flew past the Comet Halley nucleus (top image below) at a distance of 596 kilometers on March 13-14, 1986. The comet's 15-by-eight-kilometer heart was extremely dark, with powerful jets of dust and gas blasting into space.

The intrepid probe suffered damage from dust impacts - for example, one large particle sheered off more than half a kilogram of its structure - but most of its instruments continued to operate. ESA thus decided to steer it toward another comet. On July 2, 1990, five years to the day after its launch, Giotto flew past Earth at a distance of 16,300 kilometers, becoming the first interplanetary spacecraft to receive a gravity-assist boost from its homeworld. The gravity assist put it on course for Comet Grigg-Skjellurup, which it flew past at a distance of 200 kilometers on July 10, 1992. After determining that Giotto had less than seven kilograms of hydrazine propellant left on board, ESA turned it off on July 23, 1992. The inert spacecraft flew past Earth a second time at a distance of 219,000 kilometers on July 1, 1999.

By that time, a comet coma sample return mission was under way with two of the Giotto II proposers playing central roles. In late 1995, Stardust became the fourth mission selected for NASA's Discovery Program. Brownlee was Stardust Principal Investigator and Tsou, Stardust Deputy Principal Investigator, designed the mission's sample capture system. The 380-kilogram Stardust spacecraft (top image below) left Earth on a free-return trajectory on February 7, 1999 and flew past Comet Wild 2 (one of the 13 Giotto II candidates) at a distance of about 200 kilometers on January 2, 2004. Stardust captured dust particles in aerogel, a silica-based material of extremely low density that was not available when Tsou, Brownlee, and Albee proposed Giotto II.

Stardust returned to Earth on January 15, 2006. Its sample capsule streaked through the pre-dawn sky over the U.S. West Coast before parachuting to a landing on a salt pan in Utah (bottom image below). When opened on January 17, 2006 at NASA's Johnson Space Center, Stardust's 132 aerogel capture cells contained thousands of intact dust grains captured from Wild 2. Subsequent analysis indicated that some probably formed close to other stars before the Solar System was born.

"Comet Coma Sample Return via Giotto II," P. Tsou, D. Brownlee, and A. Albee, Journal of the British Interplanetary Society, Volume 38, May 1985, pp. 232-239.

Mars Sample Return quarantine & recovery (1985)

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Beginning in late 1983, a team of engineers and scientists from NASA's Johnson Space Center (JSC), the Jet Propulsion Laboratory, and Science Applications Incorporated jointly defined a Mars Sample Return (MSR) spacecraft and mission plan (top link below). Among their proposed follow-on study objectives for Fiscal Year 1985 was to better define Mars sample quarantine protocols and associated risks. In addition, the team recognized the need to rapidly recover the Mars sample after its arrival at Earth.

JSC's Solar System Exploration Division contracted with Houston-based Eagle Engineering to examine these issues and provide "rough" cost estimates. In its study, performed between May and September 1985, Eagle explored 10 options for retrieving a Mars sample following its return to Earth.

Eagle found that Direct Entry into Earth's atmosphere, with an estimated price tag of from $5.2 million to $9.8 million, would be the simplest and cheapest Mars sample recovery option, but would also carry the greatest risk (one chance in 600,000) of contaminating the terrestrial environment with potentially "malignant" martian microbes. Eagle acknowledged, however, that its contamination risk estimates (which, it explained, were based on "limited data") were arbitrary.

In Direct Entry, a reentry capsule carrying the sealed Mars sample canister would intersect Earth's atmosphere over the Pacific Ocean near Hawaii traveling at upwards of 11 kilometers per second. An ablative coating would protect the capsule from reentry heating. Eagle noted that a shallow atmosphere-entry angle would subject the sample canister to a long heat pulse, a low deceleration load, and imprecise landing site targeting (and, therefore, possible delayed recovery), while a steep angle would yield a short heat pulse, a high deceleration load, and more precise targeting.

After slowing to subsonic speed, the capsule would deploy a 5.5-meter-diameter parachute. A Defense Department transport aircraft - probably a C-130 - would snatch the descending capsule by the parachute in midair and winch it into its cargo hold, then would fly directly to the Centers for Disease Control (CDC) in Atlanta, Georgia, or to a newly constructed Planetary Sample Receiving Laboratory (PSRL) in a remote location (bottom link below). Eagle did not include the $14-million cost of the new lab in its cost estimates. The company assumed that the C-130 would be one of three similarly configured air-snatch planes in the recovery area, each of which would carry 11 aircrew on board.

Eagle's second option was Shuttle Recovery, which, the company estimated, would have only one chance in 100 million of releasing potentially harmful martian microbes into the terrestrial environment. A delta-winged Space Shuttle Orbiter would be prepositioned in Earth orbit in anticipation of the arrival of an Earth Return Vehicle (ERV) bearing the sample canister. The ERV would skim through Earth's upper atmosphere to use drag to slow down (that is, it would aerobrake) and enter an elliptical Earth orbit. It would then discard its protective aeroshell and fire a rocket motor at the apoapsis (high point) of its orbit to raise the periapsis (low point) of its orbit above the atmosphere and circularize its path around the Earth.

Eagle noted that the Shuttle Orbiter was incapable of climbing higher than about 500 kilometers above the Earth (in fact, it reached about 610 kilometers during STS-31, the Hubble Space Telescope deployment mission, in April 1990). If the ERV's orbit following the apoapsis burn was above the Shuttle altitude limit, then the Orbiter would need to deploy a teleoperated Orbital Maneuvering Vehicle (OMV). The OMV would match orbits with the ERV, dock with it, lower its orbit, and then separate.

After the Shuttle Orbiter rendezvoused with the ERV, the astronauts would capture it using their spacecraft's robot arm and place it inside a seven-ton biological containment/sample cooling container in the Orbiter's payload bay for return to Earth. The container would, Eagle wrote, be designed to survive intact a Shuttle accident during reentry and landing. A slightly cheaper but "significantly" more risk-fraught alternative would be for a spacewalking astronaut to extract the sample canister from the ERV and carry it into the two-deck Orbiter crew cabin for return to Earth.

Eagle placed the cost of the Shuttle return option at between $150 million and $173 million, of which $120 million would, in theory, pay for the Space Shuttle flight (in practice, Space Shuttle flights were considerable more expensive than this). The company also examined recovery of the sample from a high elliptical Earth orbit (the 1984 JSC/JPL/SAI design study proposed that the ERV capture into such an orbit). Eagle found that the Orbital Transfer Vehicle (OTV) required to reach such an orbit would boost their estimated cost by from $50 million to $100 million.

Eagle's third recovery option was Recovery to Space Station Structure. The company estimated that for this and all subsequent recovery options, the likelihood that harmful martian microbes could escape into Earth's environment would be less than one chance in 100 million. A Shuttle Orbiter would deliver to NASA's Space Station in 500-kilometer-high Earth orbit a biological containment/sample cooling container and three tons of propellants for a Station-based OMV. This would, the company noted, make use of about half the Shuttle's payload capacity, leaving the other half for additional Station-bound cargo unrelated to the sample recovery operation.

Spacewalking astronauts would attach the containment/cooling container to the Station's exterior. Some time after that, the ERV would aerobrake and maneuver into a circular orbit. The Station crew would then dispatch an OMV to recover it and bring it to the Station.

The Station's robot arm would transfer the ERV from the OMV to the containment/cooling container. A Shuttle mission to the Station would then collect the container for return to Earth, along with about half a payload bay of Earth-bound cargo unrelated to the sample recovery operation. Eagle placed the cost of this option at between $167 million and $193 million.

Option 4, Space Station Sample Repackaging, would see a Shuttle Orbiter deliver parts for modifying the Life Sciences Module (LSM) airlock that was expected to be part of the Space Station along with propellants for a Station-based OMV. Alternately, a Shuttle mission would detach the LSM from the Station and transport it to Earth for modification, after which a second Shuttle mission would return it to the Station.

The OMV would capture the ERV and deliver it to the LSM airlock, where astronauts would extract the sample canister and repackage it within a small biological containment/sample cooling container. The container would then be returned to Earth inside a Shuttle Orbiter crew cabin. The ERV would remain in quarantine inside the LSM airlock until scientists in the PRSL on Earth had analyzed the returned Mars sample and determined that it posed no threat. Eagle estimated that this option would cost between $302 million and $714 million.

Option 5, for which Eagle had little enthusiasm, was dubbed Minimal Sample Analysis at Space Station. It would closely resemble Option 4, except that a small sub-sample would removed from the sample canister in the LSM for "minimal" biological analysis. "There is some question," the company noted, "as to how much use a minimal analysis would be." Eagle placed the cost of this option at between $316 million and $749 million.

Eagle's Option 6, Small Sample Sterilized at Station and Sent to Earth, was also derived from its Option 4. Astronauts would remove a sub-sample and heat it enough to kill martian microbes while preserving evidence of their existence. A Shuttle Orbiter would then transport the sub-sample to Earth. The remainder of the sample (and, possibly, the Station crew) would remain in quarantine until scientists in the PSRL had checked out the sub-sample. Eagle placed this option's cost at between $316 million and $927 million.

After Option 6, Eagle's proposed sample-handling options became much more complex and expensive, adding significantly to the cost of returning a sample from Mars. Option 7, Separate Quarantine Module Attached to Station, would see a Shuttle Orbiter dock a specialized LSM-derived Quarantine Module (QM) to the Station. Eagle noted that the cost of "[d]edicated facilities. . .will seem more reasonable if a number of sample return missions are envisioned," and added that "[m]anned Mars missions might. . .use the [QM]" for quarantine of astronauts returning from Mars.

No pressurized passageway would link the Station to the QM while it held a Mars sample. If the QM were considered to be a permanent module of the Space Station, then it might be connected to it by a pressurized tunnel when no Mars sample was present and put to non-sample-related uses.

Alternately, the QM might be attached to the Station only when a sample was due to arrive from Mars. After the sample was placed in the QM, a Shuttle Orbiter would detach the module and transport it to Earth. Another Orbiter would return the empty QM to the Station when the next Mars sample was due to arrive in Earth orbit. Eagle estimated that Option 7 would cost between $605 million and $1.04 billion.

Antaeus Lab Module Attached to Station, Eagle's Option 8, took its name from the 1981 Antaeus report (middle link below), which described a purpose-built Orbital Quarantine Facility (OQF) space station. The Antaeus module, which would be capable of supporting long-term detailed sample analysis on much the same scale as the Earth-based PRSL, would replace or augment the Station's LSM.

If researchers working in the Antaeus module found that the Mars sample was safe, then it would be transported to Earth. If, on the other hand, the sample were found to contain harmful martian microbes, then the Antaeus module would be detached and boosted into a 1270-kilometer-high long-term orbit using an OMV. In the event that harmful microbes escaped from the Antaeus module and contaminated the Space Station, then an OMV could boost the entire Station into a 650-kilometer-high orbit. Eagle estimated that orbit-raising maneuvers could extend the orbital lifetime of the Antaeus module or Station for long enough to permit NASA to develop a large rocket stage that could boost the contaminated Antaeus module or Station into interplanetary space.

Augmenting the Space Station with the Antaeus module would require perhaps eight Shuttle flights at an estimated cost of $120 million each, for a total of $960 million. The company placed the total cost of Option 8 at between $1.863 billion and $2.456 billion.

Eagle's Option 9, the 1/2 Quarantined Space Station, would be nearly identical to its Option 8, except that the Station modules that would support the scientists analyzing the sample in the Antaeus module would be isolated from the rest of the Station. This would be achieved by closing pressure hatches between the two halves of the Station and slightly reducing air pressure in the quarantined modules. Eagle expected that this option would cost the same as Option 8, though it added that "detailed study may show this option to have a somewhat higher cost."

Option 10, a Dedicated Antaeus Space Station identical to that described in the Antaeus report, would constitute a new (albeit small) independent space station in Earth orbit, making it the costliest of the 10 options. Eagle estimated that the Antaeus station would cost between $5.101 billion and $7.107 billion. This option would make unnecessary the PSRL on Earth since all quarantine and analysis would take place in Earth orbit. The company declared that Option 10 was "without a doubt the safest, biologically, of all the options," but added that "the price paid for this additional safety seems unreasonably high."

Having examined the 10 options, each more complex than the last, Eagle judged that Options 1, 2, and 3 would be adequate for Mars sample quarantine. The probability of a biological accident involving a Mars sample was simply too minute to justify the greater cost of Options 4 through 10.

The company then examined methods of Earth-orbital sample recovery. It assumed that, during Mars-Earth transfer, the sample would be preserved at cold Mars-like temperatures to maintain its scientific integrity. Earth orbit is, however, warmer than interplanetary space because Earth radiates heat. This would make difficult keeping the Mars sample cold for long periods in Earth orbit, so rapid recovery would be desirable.

Eagle also assumed that an ERV that employed rocket motors to slow itself so that Earth's gravity could capture it would end up in a high elliptical Earth orbit (700 kilometers by 40,000 kilometers or 700 kilometers by 70,000 kilometers, with orbital periods of 12 or 24 hours, respectively). This would have the advantage of placing it well away from the Earth's radiated heat through most of its orbit, but would also delay sample recovery.

For recovery from elliptical orbit, the planned OMV design would be inadequate, so Eagle invoked a new-design Orbital Transfer Vehicle (OTV) based on the Centaur upper stage. Recovery using an OTV based at the Station would be problematic because the Station's orbital plane would shift 6° per day relative to the ERV, forcing the OTV to burn a considerable quantity of propellant to match orbits with the ERV and return with it to the Station. Eagle found that the best-case recovery time for a sample in elliptical orbit would be equal to one orbital period (12 or 24 hours) plus about four hours, leading to totals of 16 or 28 hours.

A sample in a 500-kilometer circular orbit, on the other hand, would be subjected to more Earth-radiated heat, but could be recovered by a Shuttle Orbiter or an Orbiter- or Station-based OMV in as little as six hours. Providing the ERV with enough propellant to circularize its orbit at 500-kilometer altitude would, however, increase its mass by 2.5 times over the elliptical-orbit ERV. This would constitute "an unacceptable penalty," Eagle judged.

Planetary Sample Rapid Recovery and Handling, Report No. 85-105, Eagle Engineering, September 20, 1985.

http://beyondapollo.blogspot.com/2010/09/jpljsc-mars-sample-return-study-i-1984.html

http://beyondapollo.blogspot.com/2009/09/antaeus-report-1978.html

http://beyondapollo.blogspot.com/2010/11/mars-sample-receiving-facility-1990.html