Encyclopedia Astronautica

Gemini Docked to Centaur for Circumlunar Flight
Credit: © Mark Wade
Gemini lunar
Gemini-Centaur docked configuration. Launched separately, the Gemini would have docked with the Centaur stage in low earth orbit. The Centaur would then fire, placing the Gemini on a circumlunar trajectory.
Credit: © Mark Wade
Gemini-Centaur-LM 640 pixel
Credit: © Mark Wade
American manned lunar flyby spacecraft. Study 1962. In the first Gemini project plans, it was planned that after a series of test dockings between Gemini and Agena rocket stages, Geminis would dock with Centaur stages for circumlunar flights.

This was a threat to Project Apollo and was suppressed.

At its birth Gemini was known as the Mercury Mark II program. NASA was already committed to the three-man Apollo spacecraft and considered Gemini an interim spacecraft to test rendezvous, docking, and EVA techniques before Apollo was available. But NASA's James Chamberlin and McDonnell Aircraft considered Gemini as a viable competitor to Apollo for the circumlunar and lunar landing missions. Such proposals might have been welcomed by the later 'cheaper, better, faster' NASA. But in 1961, as a direct challenge to the Apollo project and Lyndon Johnson's dream of a Southern High Technology Crescent, they were anathema.

The original August 14, 1961 Mercury Mark II program plan went like this:

  • Date: Flight: Description
  • Mar 1963: Gemini 1: Unmanned orbital
  • May 1963 : Gemini 2: Manned orbital
  • Jul 1963 : Gemini 3: 7-day manned orbital
  • Sep 1963 : Gemini 4: 7-day manned orbital
  • Nov 1963 : Gemini 5: Agena docking
  • Jan 1964 : Gemini 6: 14-day primate orbital
  • Mar 1964 : Gemini 7: Agena docking
  • May 1964 : Gemini 8: 14-day primate orbital
  • Jul 1964 : Gemini 9: Agena docking
  • Sep 1964 : Gemini 10: Agena docking
  • Nov 1964 : Gemini 11: Centaur docking, boost to high Earth orbit
  • Jan 1965 : Gemini 12: Centaur docking, boost to high Earth orbit
  • Mar 1965 : Gemini 13: Centaur docking, boost to Lunar flyby
  • May 1965 : Gemini 14: Centaur docking, boost to Lunar flyby
The Centaur would be launched atop a Titan II booster. The lunar Gemini spacecraft would have weighed 3,170 kg, an extra 270 kg over the basic rendezvous Gemini. The difference consisted of a backup inertial navigator and additional heat shielding for re-entry at 11 km/sec instead of 8 km/sec. This program was estimated to put an American around the moon for only $ 60 million more than the basic $ 356 million program. An even more aggressive alternative, a nine-flight program, was promised to cost only $ 8.5 million more than the basic program and fly around the moon in May 1964! This first attempt to fly Gemini to the moon was quickly suppressed, and a revision of the plan was issued only a week later, with all mention of lunar flights deleted.


Crew Size: 2. Habitable Volume: 2.55 m3.

Gross mass: 3,170 kg (6,980 lb).

More... - Chronology...

Associated Countries
See also
  • Gemini The Gusmobile could have conquered space - faster, better cheaper. An endless number of Gemini derivatives would have performed tasks in earth orbit, and flown around and landed on the moon. Could the US have won the moon and space station races at a fraction of the expense? Browse through the many might-have-been Geminis! More...
  • Manned Circumlunar Boosting a manned spacecraft on a loop around the moon, without entering lunar orbit, allows a trip to be made near the moon with a total low earth orbit mass of as little as 20 tonnes. This was attractive during the space race as a manned mission that could be accomplished early with limited booster power. Gemini, Apollo, and Soyuz were all supposed to have made circumlunar flights. Only Soyuz reached the circumlunar flight-test stage under the L1 program. Any L1 manned missions were cancelled after the Americans reached lunar orbit with Apollo 8. The idea was resurrected in 2005 when a $100 million commercial flight around the moon was proposed, again using Soyuz. More...

Associated Launch Vehicles
  • Titan American orbital launch vehicle. The Titan launch vehicle family was developed by the United States Air Force to meet its medium lift requirements in the 1960's. The designs finally put into production were derived from the Titan II ICBM. Titan outlived the competing NASA Saturn I launch vehicle and the Space Shuttle for military launches. It was finally replaced by the USAF's EELV boosters, the Atlas V and Delta IV. Although conceived as a low-cost, quick-reaction system, Titan was not successful as a commercial launch vehicle. Air Force requirements growth over the years drove its costs up - the Ariane using similar technology provided lower-cost access to space. More...

Associated Manufacturers and Agencies
  • NASA American agency overseeing development of rockets and spacecraft. National Aeronautics and Space Administration, USA, USA. More...
  • McDonnell American manufacturer of spacecraft. McDonnell, St Louis, USA. More...

  • Baker, David, The History of Manned Spaceflight, Crown, New York, 1981.
  • Hacker, Barton C and Crimwood, James,, On the Shoulders of Titans, Government Printing Office, 1977. Web Address when accessed: here.
  • Hall, Edwin H, "Memorandum to Deputy Director, Gemini Program, "Circumlunar Missions"", June 29, 1965.
  • Big G, Briefing, McDonnell Douglas, 20 December 1967.
  • Advanced Gemini Spacecraft, Briefing, McDonnell Douglas, ca. 1967.
  • Marks, C D and Quest, R G, "Low Cost Orbital Transportation: How Big A Step!", AAS Science and Technology Series, Vol. 21, 1969.

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