Apollo program

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Apollo program insignia
Apollo program insignia

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

Background

The Apollo Program was the second United States human spaceflight program, though its flights followed both the first such program (Mercury) and the third (Gemini). Apollo was originally conceived late in the Eisenhower administration as a follow-on to Mercury for advanced manned earth-orbital missions. It 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..." (Excerpt from "Special Message to the Congress on Urgent National Needs" [1])

Choosing a Mission Mode

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 minimizing risk to human life, cost and demands on technology and astronaut skill.

Three possible plans were considered.

  • Direct ascent: The first was to boost a spaceship directly to the moon. This would have required a Nova rocket far more powerful than any in existence at the time. The entire spacecraft would land on and return from the moon.
  • Earth orbit rendezvous: 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 entire spacecraft would have landed on the moon in this case as well.
  • Lunar orbit rendezvous: 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 Earth's atmosphere. The LM would separate from the CSM in lunar orbit and carry two astronauts for the descent to the lunar surface.

Apollo Command and Service Modules

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 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 the large numbers of dockings and undockings needed to make the plan succeed.

File:LM illustration 01.jpg
Apollo Lunar Module


Flights

The Apollo program included eleven manned flights, designated Apollo 7 through Apollo 17, all launched from the Kennedy Space Center, Florida. Apollo 2 through Apollo 6 were unmanned test flights; the Apollo 1 designation was retroactively applied to the originally planned first manned flight which ended in a disastrous fire during a launch pad test that killed three astronauts. The first of the manned 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 human 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 manned landing in the lunar highlands. Apollo 17, the final mission, was the first to include a scientist-astronaut.

End of the Program

Originally three additional lunar landing missions had been planned, as Apollos 18 through 20. In light of the drastically shrinking NASA budget and the decision not to produce a second batch of Saturn Vs, 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.

Another excerpt from Kennedy's Special Message to Congress:

"I believe we should go to the moon. But I think every citizen of this country as well as the Members of the Congress should consider the matter carefully in making their judgment, to which we have given attention over many weeks and months, because it is a heavy burden, and there is no sense in agreeing or desiring that the United States take an affirmative position in outer space, unless we are prepared to do the work and bear the burdens to make it successful. If we are not, we should decide today and this year.
"This decision demands a major national commitment of scientific and technical manpower, material and facilities, and the possibility of their diversion from other important activities where they are already thinly spread. It means a degree of dedication, organization and discipline which have not always characterized our research and development efforts. It means we cannot afford undue work stoppages, inflated costs of material or talent, wasteful interagency rivalries, or a high turnover of key personnel.
"New objectives and new money cannot solve these problems. They could in fact, aggravate them further--unless every scientist, every engineer, every serviceman, every technician, contractor, and civil servant gives his personal pledge that this nation will move forward, with the full speed of freedom, in the exciting adventure of space." (Excerpt from "Special Message to the Congress on Urgent National Needs")

Reasons for Apollo

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 manned 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 them from reaching the moon. Until the 1990s they denied that they had even tried.

The Apollo program stimulated many areas of technology. The flight computer design used in both the lunar and command modules was the first to use integrated circuits and magnetic core memory. Apollo rapidly forced Texas Instruments to make the circuits 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 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.

Miscellaneous information

The cost of Apollo program: $25.4 billion

Amount of moon material brought back by Apollo program: 381.7 kg

The name Apollo refers to the Greek god.

Missions

Something to note with Apollo flights is that Marshall Space Flight Center who designed the Saturn rockets referred to the flights as Saturn-Apollo (SA) whereas Kennedy Space Center referred to the flights as Apollo-Saturn (AS). This is the reason why the unmanned Saturn 1 flights are referred to as SA and the unmanned Saturn 1B are referred to as AS.

Unmanned Saturn 1

  • SA-1 - Test of the S-1 Rocket
  • SA-2 - Test of the S-1 Rocket and carried 109,000 litres into the upper atmosphere to investigate effects on radio transmission and changes in local weather conditions.
  • SA-3 - Same as SA-2
  • SA-4 - Test effects of premature engine shutdown
  • SA-5 - First flight of live second stage
  • A-101 - Tested the structural integrity of a boilerplate Apollo Command and Service Module
  • A-102 - Carried the first programmable computer on the Saturn 1 launch vehicle; last test flight
  • A-103 - carried Pegasus satellite which investigated micrometeorite impacts in Earth orbit
  • A-104 - Same as A-102
  • A-105 - Same as A-102

Unmanned Pad Abort Tests

Unmanned Little Joe II

  • A-001 - test launch escape system after launch
  • A-002 - same as A-001
  • A-003 - same as A-001
  • A-004 - same as A-001

Unmanned Apollo-Saturn

Manned

  • Apollo 1 - crew perished in fire during a test
  • Apollo 7 - first manned Apollo flight, first manned flight of the Saturn IB
  • Apollo 8 - first manned flight around the Moon, first manned flight of the Saturn V
  • Apollo 9 - first manned flight of the Lunar Module
  • Apollo 10 - first manned flight of the Lunar Module around the Moon
  • Apollo 11 - first manned landing on the Moon
  • Apollo 12 - first precise manned landing on the Moon
  • Apollo 13 - aborted landing after oxygen tank exploded en route
  • Apollo 14 - Alan Shepard becomes the only Mercury astronaut to walk on the moon
  • Apollo 15 - first mission with the Lunar Rover vehicle
  • Apollo 16 - first landing in the lunar highlands
  • Apollo 17 - final Apollo lunar mission

Cancelled Missions

Later missions using leftover Apollo hardware

See also

Previous Program:
Gemini program		 Next Program:
Space Shuttle program

Further reading

  • Gene Kranz, Failure is Not an Option. Kranz was a chief flight controller during the Mercury, Gemini and Apollo space programs. ISBN 0743200799
  • Andrew Chaikin, A Man on the Moon. Chaikin has interviewed all the surviving astronauts, plus many others who worked with the program. ISBN 0140272011
  • Charles Murray, and Catherine Bly Cox, Apollo: The Race to the Moon. This is an excellent account of what it took to build and fly Apollo. ISBN 0671611011
  • Don E. Wilhelms, To a Rocky Moon. Tells the History of Lunar exploration from a Geologists point of view. ISBN 0816510652
  • Charles R. Pellegrino, and Joshua Stoff, Chariots for Apollo: The Untold Story Behind the Race to the Moon. Tells Grumman's story of building the Lunar Modules. ISBN 0380802619
  • Jim Lovell and Jeffrey Kluger, Lost Moon: The perilous voyage of Apollo 13 also called Apollo 13: Lost Moon. Details the flight of Apollo 13. ISBN 0618056653
  • Michael Collins, Carrying the Fire; an Astronaut's journeys. Astronaut Mike Collins autobiography of his experiences as an astronaut, including his flight aboard Apollo 11, the first landing on the Moon
  • Donald K. Slayton and Michael Cassutt, Deke! An Autobiograpy. This is an excellent account of Deke Slayton's life as an astronaut and of his work as chief of the astronaut office, including selection of the crews which flew Apollo to the Moon. ISBN 031285918X
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