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Apollo Program

Introduction

Armstrong1.jpgThe Apollo program was a series of human spaceflight missions undertaken by the United States, during the years 1961–1974, using the Apollo spacecraft and the Saturn space launch vehicle.[1] It was conducted by the National Aeronautics and Space Administration (NASA) and was devoted to the goal, expressed in a 1961 address to the U.S. Congress by U.S. President John F. Kennedy, of "... landing a man on the Moon and returning him safely to the Earth ..." within the decade of the 1960s.[2] That goal was successfully achieved by the Apollo 11 mission in July 1969.

The program continued until 1975 with five subsequent Apollo missions which also landed astronauts on the Moon, the last in December 1972. In the six successful Apollo spaceflights, twelve men walked on the Moon. As of 2011, these are the only times that humans have landed on another celestial body.

Despite the many successes, there were two major failures, the first of which resulted in the deaths of three astronauts, Virgil "Gus" Grissom, Ed White and Roger Chaffee, in the Apollo 1 launchpad fire.[3] The second was an explosion on Apollo 13, in whose aftermath the deaths of three more astronauts were averted by the efforts of flight controllers, project engineers, and backup crew members.[4]

The Apollo program was named after the Greek god of the Sun.
 

 

Background

The Apollo program was originally conceived early in 1960, during the administration of President Dwight D. Eisenhower, as a follow-up to America's Mercury program. While the Mercury capsule could only support one astronaut on a limited Earth orbital mission, the Apollo spacecraft was intended to be able to carry three astronauts on a circumlunar flight and perhaps even on a lunar landing. The program was named after the Greek god of the Sun by NASA manager Abe Silverstein, who later said that "I was naming the spacecraft like I'd name my baby."<ref name=MurrayCox/> While NASA went ahead with planning for Apollo, funding for the program was far from certain, particularly given Eisenhower's equivocal attitude to manned spaceflight.[5]

Armstrong2.jpgIn November 1960, John F. Kennedy]] was elected President after a campaign that promised American superiority over the Soviet Union in the fields of space exploration and missile defense. Using space exploration as a symbol of national prestige, he warned of a "missile gap" between the two nations, pledging to make the United States not "first but, first and, first if, but first period."[6] Despite Kennedy's rhetoric, he did not immediately come to a decision on the status of the Apollo program once he was elected President. He knew little about the technical details of the space program, and was put off by the massive financial commitment required by a manned Moon landing.[7] . When NASA Administrator James Webb requested a thirty percent budget increase for his agency, Kennedy supported an acceleration of NASA's large booster program but deferred a decision on the broader issue.[8]

On April 12, 1961, Soviet cosmonaut Yuri Gagarin became the first man to fly in space, reinforcing American fears about being left behind in a technological competition with the Soviet Union. At a meeting of the U.S. House Committee on Science and Astronautics, held only the day after Gagarin's flight, many congressmen pledged their support for a crash program aimed at ensuring that America would catch up.[9] Kennedy, however, was circumspect in his response to the news, refusing to make a commitment on America's response to the Soviets.[10] On April 20, Kennedy sent a memo to Vice President Lyndon B. Johnson, asking Johnson to look into the status of America's space program, and into programs that could offer NASA the opportunity to catch up.[11] Johnson responded on the following day, concluding that "we are neither making maximum effort nor achieving results necessary if this country is to reach a position of leadership."[12] His memo concluded that a manned Moon landing was far enough in the future to make it possible that the United States could achieve it first.[13]

On May 25, 1961, Kennedy announced his support for the Apollo program as part of a special address to a joint session of Congress:[14]
"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."
At the time of Kennedy's speech, only one American had flown in space—less than a month earlier—and NASA had not yet sent a man into orbit. Some NASA employees disbelieved that Kennedy's ambitious goal could be met.[15]
 

Choosing a mission mode

Once President Kennedy had defined a goal, the Apollo mission planners were faced with the challenge of designing a set of flights that could meet this stated goal while minimizing risk to human life, cost, and demands on technology and astronaut skill. Four possible mission modes were considered:
  • Direct Ascent: A spacecraft would travel directly to the Moon, landing and returning as a unit. This plan would have required a very powerful booster, the planned Nova rocket.
  • Earth Orbit Rendezvous (EOR): Two Saturn V rockets would be launched, one carrying the spacecraft and one carrying a propulsion unit that would have enabled the spacecraft to escape Earth orbit. After a docking in Earth orbit, the spacecraft would have landed on the Moon as a unit.
  • Lunar Surface Rendezvous: Two spacecraft would be launched in succession. The first, an automated vehicle carrying propellants, would land on the Moon and would be followed some time later by the manned vehicle. Propellant would be transferred from the automated vehicle to the manned vehicle before the manned vehicle could return to Earth.
  • Lunar Orbit Rendezvous (LOR): One Saturn V would launch a spacecraft that was composed of modular parts. A command module would remain in orbit around the Moon, while a lunar module would descend to the Moon and then return to dock with the command module while still in lunar orbit. In contrast with the other plans, LOR 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.

In early 1961, direct ascent was generally the mission mode in favor at NASA. Many engineers feared that a rendezvous, which had never been attempted in space, would be impossible in lunar orbit. However, dissenters including John Houbolt at Langley Research Center emphasized the important weight reductions that were offered by the LOR approach. Throughout 1960 and 1961, Houbolt campaigned for the recognition of LOR as a valid and practical option. Bypassing the NASA hierarchy, he sent a series of memos and reports on the issue to Associate Administrator Robert Seamans; while acknowledging that he spoke "somewhat as a voice in the wilderness", Houbolt pleaded that LOR should not be discounted in studies of the question.[16]

Seamans established a ad-hoc cpmmittee in July 1961 (the Golovin committee)in July 1961 that subsequently recommended in favor of a hybrid EOR-LOR mode, but its consideration of LOR, as well as Houbolt's ceaseless work, played an important role in publicizing the workability of the approach. In late 1961 and early 1962, members of NASA's Space Task Group at the Manned Spacecraft Center in Houston began to come around to support for LOR.[17] The engineers at Marshall Space Flight Center took longer to become convinced of its merits, but their conversion was announced by Wernher von Braun at a briefing in June 1962. NASA's formal decision in favor of LOR was announced on July 11, 1962. Space historian James Hansen concludes that: Without NASA's adoption of this stubbornly held minority opinion in 1962, the United States may still have reached the Moon, but almost certainly it would not have been accomplished by the end of the 1960s, President Kennedy's target date.[18]
 

Spacecraft

Saturn.pngThe Apollo spacecraft consisted of:
  • The Command Module (CM): The part in which the astronauts spent most of their time, including launch and landing. It was 10.6 feet in height and 12.8 feet in diameter. It was the only part that returned to Earth after the mission.
  • The Service Module (SM): The part that 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 referred to as the CSM.
  • The Lunar Module (LM), also known as Lunar Excursion Module (LEM): The part of the spacecraft that actually landed on the Moon. It was comprised of a descent stage and an ascent stage, with the descent stage serving as a launch platform for the ascent stage when the lunar exploration party blasted off for lunar orbit where they would dock with the CSM prior to returning to Earth.

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. The LLRV was later replaced by the three Lunar Landing Training Vehicles (LLTV), which were the primary training vehicles used by the astronauts.

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.
 

Apollo missions and astronauts

The Apollo program included a number of unmanned test missions and 11 manned missions. The 11 manned missions included two Earth-orbiting missions (Apollo 7 and Apollo 9), two lunar-orbiting missions (Apollo 8 and Apollo 10), six successful lunar-landing missions, and one mission which was aborted, performed a lunar swingby, and successfully returned to Earth on an emergency basis. During the six lunar landings, on an overall basis, 12 different men lived, walked and worked on the surface of the Moon for a combined total of about 12.5 days.

The distance to the Moon at the apogee of its orbit around Earth is 405,000 km (252,000 miles). At the perigee of its orbit around Earth, the distance is 363,000 km (226,000 miles). Each of the manned Apollo missions took about 3 days to reach the moon.

The table just below lists all of the Apollo program missions that began in February of 1966 and culminated in July 1969 with Apollo 11 achieving the first manned landing on the Moon:[19] [20] [21]
[22]
 
ApolloTable1.png

The table below lists the final 6 missions of the Apollo program, of which 5 included successful manned landings on the Moon. One of those missions (Apollo 13) had to be aborted before it could achieve a lunar landing, but the spacecraft and its crew successfully returned to Earth under emergency conditions.[23]
 
ApolloTable2.png
 

Legacy of the Apollo program

BlueMarble.jpgThe Apollo program in general, and the Apollo 11 landing on the Moon in particular, should be viewed as a watershed in the history of the United States. It demonstrated both the technological and economic virtuosity of the United States and established technological preeminence over rival nations -- the primary goal of the program when first envisioned by President Kennedy in 1961.

It had been an enormous undertaking involving "20,000 companies and hundreds of thousands individuals",[24] as well as costing about $25.5 billion[25] (about $170 billion in 2005 dollars),[26] Only the building of the Panama Canal rivaled the Apollo program's size as the largest non-military technological endeavor ever undertaken by the United States ... and only the Manhattan Project to build the atomic bomb in World War II was comparable in a wartime setting.

The Apollo program gave the people of the world a new view of the planet Earth. On their outward voyage to the Moon, the crew of Apollo 8 focused a television camera on Earth and for the first time humanity saw its home as a tiny, lovely, and fragile "blue marble" hanging in the blackness of space. The modern environmental movement was galvanized in part by this new perception of the planet and the need to protect it and the life that it supports.

The Apollo program resulted in stimulating many areas of technology. The flight computer design used in both the Lunar and Command Modules was, along with the Minuteman Missile System, the driving force behind early research into integrated circuits. The fuel cell developed for this program was the first practical fuel cell. Computer Numerical Control (CNC) of machining was pioneered in fabricating Apollo structural components.

 

References

  1. ^ W.D. Compton (1996), Where No Man Has Gone Before: A History of Apollo Lunar Exploration Missions, Diane Publishing, ISBN 0-7881-3633-X. Available online at Google books
  2. ^ Special Message to the Congress on Urgent National Needs May 25, 1961.
  3. ^ Apollo 1 NASA history of Apollo 1, including crew bios, the tragic fire, investigation, and conclusions.
  4. ^ Apollo13 Mission Report. Apollo Lunar Surface Journal. Mission Reports.
  5. ^ Charles Murray and Catherine Bly Cox (1989), The Race to the Moon, Simon and Schuster, ISBN 0-671-61101-1.
  6. ^ Editors: Roger D. Launius and Howard E McCurdy (1997), Spaceflight and the Myth of Presidential Leadership, University of Illinois Press, ISBN 0-252-06632-4. See page 51, "Kennedy and the Decision to Go to the Moon", Martin Beschloss.
  7. ^ Hugh Sidey (1964), John F. Kennedy, President, 1st Edition, Atheneum.
  8. ^ Same as Reference 6.
  9. ^ "Discussion of Soviet Man-in-Space Shot", Hearing before the Committee on Science and Astronautics, U.S. House of Representatives, 87th Congress, First Session, April 13, 1961.
  10. ^ Same as Reference 7
  11. ^ John F. Kennedy, Memorandum for Vice President, April 20, 1961
  12. ^ Lyndon B. Johnson, Vice President, Memorandum for President, April 28, 1961
  13. ^ Same as Reference 12.
  14. ^ Same as Reference 2.
  15. ^ Same as Reference 5.
  16. ^ Chariots for Apollo: A History of Manned Lunar Spacecraft Courtney G. Brooks, James M. Grimwood and Loyd S. Swenson, NASA Special Publication-4205 in the NASA History Series, 1979. See Chapter 3.
  17. ^ Enchanted Rendezvous: John C. Houbolt and the Genesis of the Lunar-Orbit Rendezvous Concept James R. Hansen, December 1995. NASA, Monographs in Aerospace History, Series #4.
  18. ^ Same as Reference 17.
  19. ^ Unmanned Apollo-Saturn Missions From the Kennedy Space Center website.
  20. ^ Human Spaceflight From the NASA website.
  21. ^ Kennedy Space Center Apollo Manned Flight Summaries From the Kennedy Space Center website.
  22. ^ Flights Index From website of the Encyclopedia Astronautica
  23. ^ Same as References 19, 20, 21 1n2 22.
  24. ^ Apollo 11 Lunar Surface Journal adapted from originals in the National Archives Records Administration (NARA), March 1966. Published on the NASA website.
  25. ^ Note: The term "billion", wherever used in this article, means 109
  26. ^ A Congressional Budget Office Study: A Budgetary Analysis of NASA’s New Vision for Space Exploration September 2004. A quote from the bottom part of pdf page 38 of 58 pdf pages: "The total cost of the [Apollo] program in 2005 dollars was about $170 billion."

 

Contributor

  • Milton Beychok