Skylab

Before re-entry, NASA ground controllers tried to adjust Skylab's orbit to minimize the risk of debris landing in populated areas,[8] targeting the south Indian Ocean, which was partially successful.[10] The development of the transistor, the solar cell, and telemetry, led in the 1950s and early 1960s to uncrewed satellites that could take photographs of weather patterns or enemy nuclear weapons and send them to Earth.A large station was no longer necessary for such purposes, and the United States Apollo program to send men to the Moon chose a mission mode that would not need in-orbit assembly.Although concentrating on the Moon missions, von Braun also detailed an orbiting laboratory built out of a Horizon upper stage,[12] an idea used for Skylab.[24] A reason von Braun, head of NASA's Marshall Space Flight Center during the 1960s, advocated a smaller station after his large one was not built was that he wished to provide his employees with work beyond developing the Saturn rockets, which would be completed relatively early during Project Apollo.Apollo X would have replaced the LM carried on the top of the S-IVB stage with a small space station slightly larger than the CSM's service area, containing supplies and experiments for missions between 15 and 45 days' duration.On reaching orbit, the S-II second stage would be vented to remove any remaining hydrogen fuel, then the equipment section would be slid into it via a large inspection hatch.The station filled the entire interior of the S-II stage's hydrogen tank, with the equipment section forming a "spine" and living quarters located between it and the walls of the booster.Further work led to the idea of building a smaller "wet workshop" based on the S-IVB, launched as the second stage of a Saturn IB.[39] NASA sent a scientist on Jacques Piccard's Ben Franklin submarine in the Gulf Stream in July and August 1969 to learn how six people would live in an enclosed space for four weeks.[40] Astronauts were uninterested in watching movies on a proposed entertainment center or in playing games, but they did want books and individual music choices.Debris from the lost micrometeoroid shield further complicated matters by becoming tangled in the remaining solar panel, preventing its full deployment and thus leaving the station with a huge power deficit.After breakfast and preparation for lunch, experiments, tests and repairs of spacecraft systems and, if possible, 90 minutes of physical exercise followed; the station had a bicycle and other equipment, and astronauts could jog around the water tank.[66] Although it had a dart set,[67] playing cards, and other recreational equipment in addition to books and music players, the window with its view of Earth became the most popular way to relax in orbit.[71] As a technology demonstration, the crew practiced flying the Automatically Stabilized Maneuvering Unit (ASMU) inside the spacious dome of the Orbital Workshop.[80] The CMG helped provide the fine pointing needed by the Apollo Telescope Mount, and to resist various forces that can change the station's orientation.[84] Skylab had a zero-gravity shower system in the work and experiment section of the Orbital Workshop[85] designed and built at the Manned Spaceflight Center.[89] The procedure for operating the shower was as follows:[87] One of the big concerns with bathing in space was control of droplets of water so that they did not cause an electrical short by floating into the wrong area.[108] Calculations made during the mission, based on current values for solar activity and expected atmospheric density, gave the workshop just over nine years in orbit.[109] The studies cited several benefits from reusing Skylab, which one called a resource worth "hundreds of millions of dollars"[121] with "unique habitability provisions for long duration space flight".[122] Because no more operational Saturn V rockets were available after the Apollo program, four to five shuttle flights and extensive space architecture would have been needed to build another station as large as Skylab's 12,400 cubic feet (350 m3) volume.[143] British mathematician Desmond King-Hele of the Royal Aircraft Establishment (RAE) predicted in 1973 that Skylab would de-orbit and crash to Earth in 1979, sooner than NASA's forecast, because of increased solar activity.[146] The reentry of the USSR's nuclear powered Cosmos 954 in January 1978, and the resulting radioactive debris fall in northern Canada, drew more attention to Skylab's orbit.Publisher Reg Murphy was reluctant to pay the money, Jeff Jarvis recalled, but NASA assured Jarvis—Caen's counterpart at the Examiner—that the station would not hit land.[8] They aimed the station at a spot 810 miles (1,300 km) south-southeast of Cape Town, South Africa, and re-entry began at approximately 16:37 UTC, July 11, 1979.Residents and an airline pilot saw dozens of colorful flares as large pieces broke up in the atmosphere;[9] the debris landed in an almost unpopulated area, but the sightings still caused NASA to fear human injury or property damage.After waiting one week for Marshall Space Flight Center to authenticate the wreckage, he collected the Examiner prize and another US$1,000 from a Philadelphia businessman who had flown Thornton's family and girlfriend there.The first option's chance of mission success was considered uncertain at best, and the second's even worse given the expected dearth of food, water, and oxygen supplies and the degraded condition of Skylab's system after two years in orbit.William Pogue credits Pete Conrad with asking the Skylab program director which scheme should be used for the mission patches, and the astronauts were told to use 1–2–3, not 2–3–4.They and the scientific community hoped to have two on each Skylab mission, but Deke Slayton, director of flight crew operations, insisted that two trained pilots fly on each.