Apollo program

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The Apollo Program: NASA

The Apollo program was a series of crewed space missions undertaken by the United States of America, conducted during the years (1961-1972). It was devoted to the goal of landing a man on the Moon and returning him safely to the earth within the decade of the 1960s. This goal was achieved with the Apollo 11 mission in 1969. The program was extended into the early 1970s to carry out the initial crewed scientific exploration of the Moon.

The Apollo Program was the third United States crewed spaceflight program, following the Mercury program and the Gemini program. Apollo was originally conceived late in the Eisenhower administration as a follow-on to Mercury for advanced earth-orbital missions. It was dramatically reoriented to an aggressive lunar landing goal by President Kennedy, announced at a special joint session of Congress on May 25, 1961:

I believe 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 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. Excerpt from "Special Message to the Congress on Urgent National Needs"

Having settled upon the Moon as a target, the Apollo mission planners were faced with the challenge of designing a flight plan attaining Kennedy's stated goal while minimising risk to human life, cost and demands on technology and astronaut skill.

Three possible plans were considered. The first was to boost a spaceship directly to the moon. This would have required a Nova booster more powerful than any planned at the time. The second known as Earth orbit rendezvous (EOR) would have required the launch of two Saturn V rockets, one containing the space ship and one containing fuel. The spaceship would have docked in earth orbit and be fueled with enough fuel to make it to the moon and back.

The plan which was actually adopted is credited to John Houbolt and used the technique of 'Lunar Orbit Rendezvous' (LOR). The spacecraft was modular, composed of a 'Command/Service Module' (CSM) and a 'Lunar Module' (LM; pronounced LEM, for Lunar Excursion Module, its initial name). The CSM contained the life support systems for the three man crew's five day round trip to the moon and the heat shield for their reentry to the Earth's atmosphere. The LM would separate from the CSM in lunar orbit and carry two astronauts for the descent to the lunar surface. The LM 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 discarded, it could be made very light and allow for the moon mission to be launched with a single Saturn V rocket. However, at the time that LOR was decided, some mission planners were uneasy at large number of dockings and undockings needed to make the plan succeed.

The Apollo program included eleven crewed flights, designated Apollo 7 through Apollo 17, all launched from the Kennedy Space Center, Florida. Apollo 2 through Apollo 6 were uncrewed test flights; the Apollo 1 designation was applied to the originally planned first crewed flight which ended in a disastrous fire during a launch pad test that killed three astronauts. The first of the crewed flights employed the Saturn 1-B launch vehicle, the following flights all used the more powerful Saturn V. Two of the flights (Apollo 7 and Apollo 9) were earth orbital missions, two of the flights (Apollo 8 and Apollo 10) were lunar orbital missions, and the remaining 7 flights were lunar landing missions (although one, Apollo 13, failed to land).

Briefly, Apollo 7 tested the Apollo command and service modules (CSM) in earth orbit. Apollo 8 tested the CSM in lunar orbit. Apollo 9 tested the lunar module (LM) in earth orbit. Apollo 10 tested the LM in lunar orbit. Apollo 11 achieved the first crewed lunar landing. Apollo 12 achieved the first lunar landing at a precise location. Apollo 13 failed to achieve a lunar landing, but succeeded in returning the crew safely to earth following a potentially disastrous in-flight explosion. Apollo 14 resumed the lunar exploration program. Apollo 15 introduced a new level of lunar exploration capability, with a long-stay-time LM and a lunar roving vehicle. Apollo 16 was the first crewed landing in the lunar highlands. Apollo 17, the final mission, was the first to include a scientist-astronaut.

Originally three additional lunar landing missions had been planned, as Apollo 18 through Apollo 20. These missions were cancelled to make funds available for the development of the Space Shuttle, and to make their Apollo spacecraft and Saturn V launch vehicles available to the Skylab program. Only one of the Saturn Vs was actually used; the others became museum exhibits.

The Apollo program was at least partly motivated by psycho-political considerations, in response to persistent perceptions of American inferiority in space technology vis-a-vis the Soviets, in the context of the Cold War. In this respect it succeeded brilliantly. In fact, American superiority in crewed spaceflight was achieved in the precursory Gemini program, even before the first Apollo flight. The inability of the Soviets to perfect their N-1 rocket prevented the Soviets from going to the moon, and led them to deny until the 1990's that they ever had a moon program.

The Apollo program stimulated many areas of technology. The identical flight computer design used in the lunar and command module were the first to use integrated circuits and magnetic core memory. The computer were called AGC (Apollo Guidance Computer). Apollo rapidly forced Texas Instruments to make them work, and provided the crucial first customer when simple integrated circuits cost more than $1000/chip (in 1960 dollars). The fuel cell developed for this program was the first practical fuel cell. Computer controlled machining (CNC) was pioneered in fabricating Apollo structural components.

Many astronauts and cosmonauts have commented on the profound effects that seeing earth from space has had on them. One of the most important legacies of the Apollo program was the now-common, but not universal view of the Earth as a fragile, small planet, captured in the photographs taken by the astronauts during the lunar missions. These photographs have also motivated many people toward environmentalism and space colonization.