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Translunar Gemini with Double Transtage - LEO Configuration

Credit: © Mark Wade. 4,989 bytes. 635 x 251 pixels.

Manufacturer's Designation: McDonnell-Douglas. Class: Manned. Type: Lunar orbiter. Nation: USA. Agency: NASA. Manufacturer: McDonnell-Douglas.

On June 24, 1965, McDonnell-Douglas and Martin Marrietta provided a detailed proposal to launch a refurbished, modified Gemini around the moon by April 1967 for $ 350 million. The Gemini would have 521 kg of mass deleted, half of it by removing the solid fuel retrograde rockets used to initiate re-entry (the liquid fuel Orbital Manoeuvring System would be reengineered to increase its reliability). The Titan 2-launched Gemini would rendezvous and dock with a Titan 3C-launched 'Double Transtage'. The Double Transtage consisted of an unmodified first Transtage that would place itself and a second Transtage into low earth orbit. The first Transtage retained the navigation and manoeuvring systems necessary to move the assembly to the rendezvous orbit with Gemini. The second Transtage would be stripped of unnecessary equipment (the orbital manoeuvring system) but was equipped with an Agena-type docking collar.

Gemini VariantsGemini Variants - Modest modifications of Gemini proposed by McDonnell Douglas as a follow-on to the basic program (927 x 723 pixel version).

Credit: McDonnell Douglas. 43,356 bytes. 927 x 723 pixels.

After docking with the Double Transtage, the first Transtage would be cast off and the second Transtage would propel the Gemini into a circumlunar trajectory. The flights themselves, assuming go-ahead was given in September 1965, would follow immediately after the last Gemini flight. In December 1966 a Titan 3C would drive a 2450 kg circumlunar Gemini capsule to 11 m/s re-entry velocity to verify the heat shield design. This would be followed by a February 1967 manned qualification flight in earth orbit. A manned Gemini would dock with a Double Transtage and be propelled into a high orbit and re-entry speed. In April the sequence would be repeated, this time the Gemini being sent by Transtage into a loop around the moon.

Lunar Orbit GeminiLunar Orbit Gemini - Lunar Orbit Gemini. In this version a Gemini docks with a Titan 3C-launched transtage, which maneuvers the Gemini into a lunar orbit and then returns it to earth.

Credit: McDonnell Douglas. 11,822 bytes. 469 x 164 pixels.

NASA engineers thought that Gemini extension efforts would be better directed towards proving space station assembly techniques and procedures using Gemini and Agena. They also thought the contractor's schedule and cost estimates to be over-optimistic. The reaction of top NASA management was more categorical. Astronaut Pete Conrad managed to stir Congressional interest, but NASA administrator James Webb informed them that any extra funds Congress cared to appropriate for such a project would be better spent accelerating the Apollo program. After further internal struggles, Conrad finally got NASA approval for the Agena on his Gemini 11 flight to boost him into a record 1,570 km orbit. This high flight was the only remnant of lunar Gemini.

Gemini/Transtage-TLIGemini/Transtage-TLI - Translunar Gemini with Transtage - Translunar Configuration

Credit: © Mark Wade. 3,548 bytes. 437 x 223 pixels.


Craft.Crew Size: 2. Design Life: 14 days. Total Length: 11.7 m. Maximum Diameter: 3.0 m. Total Habitable Volume: 2.55 m3. Total Mass: 15,200 kg. Total Propellants: 10,600 kg. Primary Engine Thrust: 7,257 kgf. Main Engine Propellants: N2O4/UDMH. Main Engine Isp: 311 sec. Total spacecraft delta v: 3,600 m/s. Electric system: 2.20 total average kW. Electric System: 150.00 total kWh. Electrical System: Fuel Cells.

Lunar Orbit Gemini Chronology

24 June 1965 Proposal to launch Gemini around the moon

Gemini contractors proposed to launch a refurbished, modified Gemini around the moon by April 1967 for $ 350 million. The Titan 2-launched Gemini would rendezvous and dock with a Titan 3C-launched 'Double Transtage', which would propel the Gemini into a circumlunar trajectory. McDonnell-Douglas and Martin Marrietta's proposal was suppressed by NASA as a threat to the Apollo program.


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Last update 12 March 2001.
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