Encyclopedia Astronautica
Gemini LOR

Gemini Docks with LM
Gemini rendezvous above lunar surface with open cockpit Lunar Module after first lunar landing in 1966
Credit: © Mark Wade
Gemini for lunar landing with Centaur and Langley open cockpit Lunar Module
Credit: © Mark Wade
American manned lunar lander. Study 1961. Original Mercury Mark II proposal foresaw a Gemini capsule and a single-crew open cockpit lunar lander undertaking a lunar orbit rendezvous mission, launched by a Titan C-3.

In September 1961 NASA's James Chamberlin came up with a plan to use a Gemini capsule to land two men on the moon and return them safely to earth at a cost 1/20 of that of the Apollo project. The key was the use of the technique of lunar orbit rendezvous and a bare-bones, open cockpit lunar module. This would weigh 4,372 kg in the storable propellant version or 3,284 kg in the cryogenic Lox/LH2 version (calculated propellant loads 3,500 kg and 2,200 kg, respectively). The total mass to be injected into an escape trajectory toward the moon would be no more than 13,000 kg, one fifth of the 68,000 kg planned for the Nova-boosted direct-lunar landing approach favored at that time. At this mass, instead of Nova, a Saturn C-3 launch vehicle could be used. The Gemini flight schedule would have been delayed by a year in order to develop a more capable spacecraft. However by launching every 45 days instead of every 60 days Gemini would still put an American on the moon by January 1966:

Titan 2 Launches
Mar 1964 Gemini 1Unmanned orbital
May 1964 Gemini 2Manned orbital
Jun 1964 Gemini 37-day manned orbital
Aug 1964 Gemini 414-day manned orbital
Sep 1964 Gemini 5Agena docking
Nov 1964 Gemini 6Agena docking
Dec 1964 Gemini 7Agena docking
Feb 1965 Gemini 8Centaur docking, boost to high Earth orbit
Mar 1965 Gemini 9Centaur docking, boost to high Earth orbit
May 1965 Gemini 10LM docking
Jun 1965 Gemini 11LM docking
Jul 1965 Gemini 12LM docking
Sep 1965 Gemini 13Centaur docking, boost to Lunar flyby
Oct 1965 Gemini 14Centaur docking, boost to Lunar flyby
Saturn C-3 Launches
Nov 1965 Gemini 15Manned Lunar orbital
Jan 1966 Gemini 16Manned Lunar landing

The lunar module would have been launched separately by Titan II for the three Earth orbital docking missions. This moon landing project was projected to cost $ 584 million 'plus the cost of two Saturn C-3's'.

Chamberlin was actually the first member of the Space Task Group (STG) to advocate lunar orbit rendezvous (LOR) as a method for reaching the moon. Earlier efforts through 1960 and 1961 by Robert Hoboult and other engineers at Langley to interest STG in the method had been seen as the impractical musings of theorists. Chamberlin and McDonnell Aircraft did not fall in this category. They saw clearly that separating the re-entry and lunar landing functions allowed optimized spacecraft designs for each role, and solved many of the intractable engineering problems the direct-ascent advocates were struggling with.

Chamberlin made one last effort at the end of September to interest STG in including lunar Gemini as part of an "Integrated Apollo Program". This involved the same flight schedule as advocated earlier, but with the cost estimate now firmed up at $ 706 million (including the Saturn boosters!), and the lunar module mass cut to 1,800 kg. NASA brass still rejected the lunar aspects of the plan, but told STG to go ahead with negotiations with McDonnell, Martin, and Lockheed for the spacecraft and boosters. Chamberlin submitted the revised plan without lunar flights on October 27, and this was approved as the basis for project Gemini.

The actual Gemini project as flown was over a year late to the original optimistic plan. This was due to delays in development of both the Titan 2 launch vehicle and the Gemini paraglider landing system. The pivotal 14-day flight actually came in December 1965 versus January 1964 in the first Mercury Mark II proposal and August 1964 in the September 1961 plan.

Apr 1964Gemini 1Unmanned booster orbital test; boilerplate spacecraft.
Jan 1965Gemini 2Unmanned suborbital test of spacecraft
Mar 1965Gemini 3 Manned orbital 
Jun 1965Gemini 44-day manned orbital
Aug 1965Gemini 58-day manned orbital
Dec 1965Gemini 714-day manned orbital
Dec 1965Gemini 6Rendezvous with Gemini 7 (Agena target failed to orbit)
Mar 1966Gemini 8 Agena docking
Jun 1966Gemini 9 Agena docking
Jul 1966Gemini 10 Agena docking
Sep 1966Gemini 11 Agena docking
Nov 1966Gemini 12 Agena docking

It was possible to estimate when Chamberlain's Gemini moon landing would have actually occurred based on the actual delays to Gemini. It must be considered that the time necessary to develop the Saturn C-3 could not have been much less than that actually taken for the C-5 (the final December 1961 C-3B configuration differed from the C-5 only in the propellant loading in each stage and in having three F-1 engines in the first stage as opposed to five in the C-5). Therefore, with perfect hindsight, if Gemini had been selected in lieu of Apollo, the actual final program would have looked about like this:

Titan 2 Launches
Apr 1964Gemini 1Unmanned booster orbital test; boilerplate spacecraft.
Jan 1965Gemini 2Unmanned suborbital test of spacecraft
Mar 1965Gemini 3 Manned orbital 
Jun 1965Gemini 44-day manned orbital
Aug 1965Gemini 58-day manned orbital
Dec 1965Gemini 714-day manned orbital
Dec 1965Gemini 6Rendezvous with Gemini 7 (Agena target failed to orbit)
Mar 1966Gemini 8 Agena docking
Jun 1966Gemini 9 Agena docking
Aug 1966 Gemini 10Centaur docking, boost to high Earth orbit
Oct 1966 Gemini 11Centaur docking, boost to high Earth orbit
Nov 1966 Gemini 12LM docking
Jan 1967 Gemini 13LM docking
Feb 1967 Gemini 14LM docking
Mar 1967 Gemini 15Centaur docking, boost to Lunar flyby
Apr 1967Gemini 16Centaur docking, boost to Lunar flyby
Saturn C-3 Launches
Aug 1967 Gemini 17Unmanned test of Saturn C-3
Feb 1968 Gemini 18Unmanned Lunar orbital test
Oct 1968 Gemini 19Manned Lunar orbital
Dec 1968 Gemini 20Manned Lunar landing

So in the end, the first lunar landing would have been moved up by six months at best. There would have been a cost savings, but again analysis of the detailed cost breakdowns for Apollo indicate the savings would have been on the order of 'only' $ 4 billion out of the NASA $ 18 billion project share. So in retrospect it would seem that NASA's management was correct, for the Apollo missions flown were much more capable than a Gemini-based approach would have been.

Crew Size: 2. Habitable Volume: 2.55 m3.

Gross mass: 13,000 kg (28,000 lb).
Span: 5.58 m (18.30 ft).

More... - Chronology...

Associated Countries
Associated Spacecraft
  • Gemini American manned spacecraft. 12 launches, 1964.04.08 (Gemini 1) to 1966.11.11 (Gemini 12). It was obvious to NASA that there was a big gap of three to four years between the last Mercury flight and the first scheduled Apollo flight. More...
  • LM Langley Light American manned lunar lander. Study 1961. This early open-cab single-crew Langley lunar lander design used storable propellants, resulting in an all-up mass of 4,372 kg. More...

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...
  • Lunar Landers Lunar lander design started with the British Interplanetary Society's concept of 1939, followed by Von Braun's 3964 tonne monster of 1953. It then settled down to more reasonably-sized variants. Landers came in three main types: two stage versions, with the first stage being a lunar crasher that would brake the spacecraft until just above the lunar surface, then separate, allowing the second stage to land on the surface; two stage versions consisting of a descent stage that went all the way to the surface, and an ascent stage that would take the crew from the surface to lunar orbit or on an earth-return trajectory; and single stage versions, using liquid oxygen/liquid hydrogen propellants. 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...

  • Ertel , Ivan D; Morse , Mary Louise; et al, The Apollo Spacecraft Chronology Vol I - IV NASA SP-4009, NASA, 1966-1974. Web Address when accessed: here.
  • 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.

Gemini LOR Chronology

1961 May 7 - . LV Family: Titan. Launch Vehicle: Titan 2.
  • Titan II proposed for lunar landing program - . Nation: USA. Related Persons: Gilruth; Seamans; Silverstein. Program: Apollo. Spacecraft: Gemini LOR. Albert C. Hall of The Martin Company proposed to Robert C. Seamans, Jr., NASA's Associate Administrator, that the Titan II be considered as a launch vehicle in the lunar landing program. Although skeptical, Seamans arranged for a more formal presentation the next day. Abe Silverstein, NASA's Director of Space Flight Programs, was sufficiently impressed to ask Director Robert R. Gilruth and STG to study the possible uses of Titan II. Silverstein shortly informed Seamans of the possibility of using the Titan II to launch a scaled-up Mercury spacecraft.

1961 July - . LV Family: Nova; Saturn C-3.
  • Improved Mercury proposed for lunar landing - . Nation: USA. Related Persons: Chamberlin. Program: Apollo. Spacecraft: Gemini LOR; Apollo Lunar Landing. James A. Chamberlin and James T. Rose of STG proposed adapting the improved Mercury spacecraft to a 35,000-pound payload, including a 5,000-pound "lunar lander." This payload would be launched by a Saturn C-3 in the lunar orbit rendezvous mode. The proposal was in direct competition with the Apollo proposals that favored direct landing on the moon and involved a 150,000-pound payload launched by a Nova-class vehicle with approximately 12 million pounds of thrust.

1961 August - .
  • Presentation to STG on rendezvous and the lunar orbit rendezvous plan - . Nation: USA. Related Persons: Chamberlin. Program: Gemini. Spacecraft: Gemini LOR. John C. Houbolt of Langley Research Center made a presentation to STG on rendezvous and the lunar orbit rendezvous plan. At this time James A. Chamberlin of STG requested copies of all of Houbolt's material because of the pertinence of this work to the Mercury Mark II program and other programs then under consideration.

1961 December 6 - .
  • Preliminary project plan for the Mercury Mark II program - . Nation: USA. Related Persons: Holmes, Brainard; Seamans. Program: Gemini. Spacecraft: Gemini LOR. D. Brainerd Holmes, NASA Director of Manned Space Flight, outlined the preliminary project development plan for the Mercury Mark II program in a memorandum to NASA Associate Administrator Robert C. Seamans, Jr. The primary objective of the program was to develop rendezvous techniques; important secondary objectives were long-duration flights, controlled land recovery, and astronaut training. The development of rendezvous capability, Holmes stated, was essential:

    • It offered the possibility of accomplishing a manned lunar landing earlier than by direct ascent.
    • The lunar landing maneuver would require the development of rendezvous techniques regardless of the operational mode selected for the lunar mission.
    • Rendezvous and docking would be necessary to the Apollo orbiting laboratory missions planned for the 1965-1970 period.
    The plan was approved by Seamans on December 7. The Mercury Mark II program was renamed "Gemini" on January 3, 1962.

Home - Browse - Contact
© / Conditions for Use