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Background The Apollo Program was originally conceived late in the Eisenhower administration as a follow-on to the Mercury program, doing advanced manned earth-orbital missions. In fact, it became the third program, following Gemini. The Apollo Program was dramatically reoriented to an aggressive lunar landing goal by President Kennedy with his announcement at a special joint session of Congress on May 25, 1961: "...I believe that this nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to the Earth. No single space project in this period will be more impressive to mankind, or more important in the long-range exploration of space; and none will be so difficult or expensive to accomplish..." The Apollo program was at least partly motivated by geopolitical considerations, in the context of the Cold War and the Space Race. Choosing a mission mode Having settled upon the Moon as a target, the Apollo mission planners were faced with the challenge of designing a set of flights that would meet Kennedy's stated goal while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible plans were considered. In contrast with the other plans, the LOR plan required only a small part of the spacecraft to land on the Moon, thereby minimizing the mass to be launched from the Moon's surface for the return trip. The mass to be launched was further minimized by leaving part of the LM (that with the descent engine) behind on the Moon. The Lunar Module itself was composed of a descent stage and an ascent stage, the former serving as a launch platform for the latter when the lunar exploration party blasted off for lunar orbit where they would dock with the CSM prior to returning to Earth. The plan had the advantage that since the LM was to be eventually discarded, it could be made very light, so the Moon mission could be launched with a single Saturn V rocket. However, at the time that LOR was decided, some mission planners were uneasy at the large number of dockings and undockings called for by the plan. To learn lunar landing techniques, astronauts practiced in the Lunar Landing Research Vehicle (LLRV), a flying vehicle that simulated (by means of a special, additional jet engine) the reduced gravity that the Lunar Module would actually fly in. Spacecraft The Apollo spacecraft consisted of three main sections, plus two minor sections. The Command Module (CM) was the part in which the astronauts spent most of their time, including launch and landing. It was the only part that returned to Earth after the mission. The Service Module (SM) housed the equipment needed by the astronauts, such as oxygen tanks, and the engine that would take the spacecraft into and out of lunar orbit. The combined Command and Service modules were called the CSM. The Lunar Module (LM) (also known as Lunar Excursion Module, or LEM), was the part of the spacecraft that actually landed on the moon. It was comprised of two stages, one for descent, and one for ascent. The Launch Escape Tower (LET) would carry the Command Module clear of the launch vehicle, should it explode during launch, and the Spacecraft Lunar Module Adapter (SLA) was used to connect the spacecraft to the Launch Vehicle. In addition, on Apollos 9 - 17, it housed and protected the Lunar Module and on the ASTP flight, it housed the docking adapter. Astronauts The following astronauts flew Apollo missions: From the Mercury Seven From Astronaut Group 2 From Astronaut Group 3 From Astronaut Group 4 From Astronaut Group 5 In addition, the following astronauts flew on Post-Apollo missions using Apollo hardware: From the Mercury Seven From Astronaut Group 4 Missions The Apollo program used four types of launch vehicles: The Marshall Space Flight Center, which designed the Saturn rockets, referred to the flights as Saturn-Apollo (SA), while Kennedy Space Center referred to the flights as Apollo-Saturn (AS). This is why the unmanned Saturn 1 flights are referred to as SA and the unmanned Saturn 1B are referred to as AS. Dates given below are dates of launch. Mission types In September 1967, the Manned Spacecraft Center in Houston, Texas, proposed a series of missions that would lead up to a manned lunar landing. Seven mission types were outlined, each testing a specific set of components and tasks; each previous step needed to be completed successfully before the next mission type could be undertaken. These were: Later added to this were H missions, which were short duration stays on the Moon with two LEVAs ("moonwalks"). These were followed by the J missions, which were longer 3 day stays, with 3 LEVAs and the use of the lunar rover. Apollo 18 to 20 would have been J missions. In addition, a further group of flights — the I missions — were planned for. Lunar Orbital Survey Missions were conceived that would have seen a long duration orbital mission of the Moon using a Service Module bay loaded with scientific equipment. When it became obvious that later flights were being cancelled, such mission plans were brought into the J missions that were actually flown. Saturn I Pad abort tests Little Joe II Unmanned Apollo spacecraft|Apollo-Saturn IB and Saturn V Manned missions The original pre-lunar landing program was more conservative but, as the 'all-up' test flights for the Saturn V proved successful, some missions were deleted. The revised schedule published in October 1967 had the first manned Apollo CSM earth orbit mission (Apollo 7) followed by an Earth Orbit Rendezvous of the CSM and LM launched on two Saturn 1Bs (Apollo 8) followed by a Saturn V launched CSM on a Large Earth Orbit Mission (Apollo 9) followed by the Saturn V launched dress rehearsal in Lunar Orbit with Apollo 10. By the summer of 1968 it became clear to program managers that a fully functional LM would not be available for the Apollo 8 mission. Rather than perform a simple earth orbiting mission, they chose to send Apollo 8 around the moon during Christmas. The original idea for this switch was the brainchild of George Low. Although it has often been claimed that this change was made as a direct response to Soviet attempts to fly a piloted Zond spacecraft around the moon, there is no evidence that this was actually the case. NASA officials were aware of the Soviet Zond flights, but the timing of the Zond missions does not correspond well with the extensive written record from NASA about the Apollo 8 decision. It is relatively certain that the Apollo 8 decision was primarily based upon the LM schedule, rather than fear of the Soviets beating the Americans to the moon. Cancelled lunar missions Post-Apollo missions using Apollo hardware and Saturn IB Launch Complex utilization Samples Returned Apollo returned 381.7kg (841.5 lb) of rocks and other material from the Moon; much is stored at the Lunar Receiving Laboratory in Houston. In general the rocks collected from the Moon are extremely old compared to rocks found on the Earth, as measured by radiometric dating techniques. The youngest of the rocks is older than most rocks seen on Earth. They range in age from 3.2 billion years from the basalt samples from the lunar mare, up to 4.6 billion years in the highlands. As such they represent samples from a very early period in the formation of the Solar System. One of the most important rocks found during the Apollo Program was the Genesis Rock, retrieved by astronauts James Irwin and David Scott of Apollo 15. The rock dates back to the formation of the moon. Many of the rocks appear to be littered with micrometeoroid impact craters, something which is never seen on earth due to the thick atmosphere, but which is possible on the moon. Apollo Applications In the speech which initiated Apollo, Kennedy declared that no other program would have as great a long-range effect on America's ambitions in outer space. Following the success of Project Apollo, both NASA and its major contractors investigated several post-lunar applications for the Apollo hardware. The "Apollo Extension Series", later called the "Apollo Applications Program", proposed up to thirty flights to Earth Orbit. Many of these would use the space that the lunar module took up in the Saturn rocket to carry scientific equipment. One plan involved using the Saturn IB to take the Command/Service Module (CSM) to a variety of low-earth orbits for missions lasting up to 45 days. Some missions would involve the docking of two CSMs, and transfer of supplies. The Saturn V would be necessary to take it to polar orbit, or sun-synchronous orbit (neither of which has yet been achieved by any manned spacecraft), and even to the geosynchronous orbit of Syncom 3, a communications satellite not quite in geostationary orbit. This was the first functioning communications satellite at that now-common great distance from the Earth, and it was small enough to be carried through the hatch and taken back to Earth for study as to the effects of radiation on its electronic components in that environment over a period of years. A return to the moon was also planned, this time to orbit for a longer time to map the surface with high-precision equipment. This mission would not include a landing. Of all the plans, only two were implemented: the Skylab space station (May 1973 – February 1974), and the Apollo-Soyuz Test Project (July 1975). Skylab's fuselage was constructed from the second stage of a Saturn IB, and the station was equipped with the Apollo Telescope Mount, itself based on a lunar module. The station's three crews were ferried into orbit atop Saturn IBs, riding in CSMs; the station itself had been launched with a modified Saturn V. Skylab's last crew departed the station on February 8, 1974, whilst the station itself returned prematurely to Earth in 1979, by which time it had become the oldest operational Apollo component. The Apollo-Soyuz Test Project involved a docking in Earth orbit between an unnamed CSM and a Soviet Soyuz spacecraft. The mission lasted from July 15 to July 24, 1975. Although the Soviet Union continued to operate the Soyuz and Salyut space vehicles, NASA's next manned mission would not be until STS-1 on April 12, 1981. In 1964/5 Grumman, the primary contrator for the Apollo LM systems, attempted to interest the USAF and Navy in a military version of CSM/LM configuration. The LM would have been equipped with a manipulator arm and projectile weapons to intercept and disable enemy satellites. The proposal was never fully developed and was abandoned in 1967. In the same time period, Grumman proposed using an Apollo spacecraft to send a mission to land on a Near-Earth asteroid. Only about half a dozen were known at the time, with close approaches occurring about every three or four years. NASA found the scheme too marginal to pursue. End of the program
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