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Description
Big Gemini (or "Big G") was proposed to NASA by McDonnell Douglas in August 1969 as an advanced version of the Gemini spacecraft system. It should provide large-capacity, all-purpose access to space, including missions that used Apollo or the Space Shuttle.

Big Gemini, or Big G, grew out of a 1963 proposal called Gemini Transport to develop an enlarged Gemini spacecraft with docking capability. It would take advantage of the increased capacity offered by the Saturn IB and Titan IIIM rockets. It transported nine or twelve astronauts into space and docked at space stations to support Apollo Applications and MOL (manned orbital laboratory). A heavy-lift launch vehicle has launched; either a Titan IIIG or Saturn INT-20, the former being intended for use on US Air Force missions and the latter being intended for NASA missions. The Titan IIIM was also considered. This would have launched a smaller version of the spacecraft because of its lower capacity to resupply MOL space stations later in the program. NASA also proposed several Saturn IB derivatives with solid first stages as alternatives to the INT-20, offering similar payload capacity.

Depending on the rocket that was to send it, the spaceship's shape and mass would vary. The Saturn-launched version had a short, conical cargo module and a total mass of 47,300 kilograms (104,300 lb). While the Titan IIIG-launched version featured a longer cylindrical module, with a total mass of 59,000 kilograms (130,000 lb). The Titan IIIM version would have been much shorter and lighter, with a mass of 15,600 kilograms (34,400 lb), as that rocket had less payload capacity than the Titan IIIG or Saturn. The IIIG variant would have carried twelve crew, while the others had a maximum capacity of nine. Using the NASA variant with the Apollo Service Module was also considered.

Once in orbit, Big G would have docked with space stations using an Apollo docking probe mounted on the rear of the cargo module, which was mounted on the rear of the re-entry module. The re-entry module itself would have been enlarged to accommodate the larger crew. Modifications to the MOL program would have been incorporated. The heat shield would have provided access to the cargo module. In the event of a launch failure, the launch escape system developed for the Apollo spacecraft would have been used to propel the re-entry module clear of the rocket.

The concept was given serious consideration. In 1971, faced with budget cuts that rendered the development of a fully-reusable space shuttle infeasible. NASA administrator George Low lamented that shuttle development might have to be delayed until the 1980s, with "something like a "big G" approach and a cheap space station" filling in as an interim. The office of management and budget (OMB) was more favorable to the idea than NASA. They concluded in a staff paper that a Big Gemini launch aboard a modernized Titan III would be a more cost-effective option than any shuttle design. Ultimately, OMB Deputy Director Caspar Weinberger helped to broker a compromise where Big G was taken off the table, and they gave NASA the green light for the immediate development of a partially-reusable thrust-assisted orbiter shuttle.

Specifications

Crew size: 9 to 12
Length: 11.5 m (38 ft)
Maximum diameter: 4.27 m (14.0 ft)
Habitable volume: 18.7 m3 (660 cu ft)
Mass: 15,590 kg (34,370 lb)
Payload: 2,500 kg (5,500 lb)

Launch vehicles: Titan 3M, Saturn IB, Saturn S-IC/S-IVB.

Description
Big Gemini (or "Big G") was proposed to NASA by McDonnell Douglas in August 1969 as an advanced version of the Gemini spacecraft system. It should provide large-capacity, all-purpose access to space, including missions that used Apollo or the Space Shuttle.

Big Gemini, or Big G, grew out of a 1963 proposal called Gemini Transport to develop an enlarged Gemini spacecraft with docking capability. It would take advantage of the increased capacity offered by the Saturn IB and Titan IIIM rockets. It transported nine or twelve astronauts into space and docked at space stations to support Apollo Applications and MOL (manned orbital laboratory). A heavy-lift launch vehicle has launched; either a Titan IIIG or Saturn INT-20, the former being intended for use on US Air Force missions and the latter being intended for NASA missions. The Titan IIIM was also considered. This would have launched a smaller version of the spacecraft because of its lower capacity to resupply MOL space stations later in the program. NASA also proposed several Saturn IB derivatives with solid first stages as alternatives to the INT-20, offering similar payload capacity.

Depending on the rocket that was to send it, the spaceship's shape and mass would vary. The Saturn-launched version had a short, conical cargo module and a total mass of 47,300 kilograms (104,300 lb). While the Titan IIIG-launched version featured a longer cylindrical module, with a total mass of 59,000 kilograms (130,000 lb). The Titan IIIM version would have been much shorter and lighter, with a mass of 15,600 kilograms (34,400 lb), as that rocket had less payload capacity than the Titan IIIG or Saturn. The IIIG variant would have carried twelve crew, while the others had a maximum capacity of nine. Using the NASA variant with the Apollo Service Module was also considered.

Once in orbit, Big G would have docked with space stations using an Apollo docking probe mounted on the rear of the cargo module, which was mounted on the rear of the re-entry module. The re-entry module itself would have been enlarged to accommodate the larger crew. Modifications to the MOL program would have been incorporated. The heat shield would have provided access to the cargo module. In the event of a launch failure, the launch escape system developed for the Apollo spacecraft would have been used to propel the re-entry module clear of the rocket.

The concept was given serious consideration. In 1971, faced with budget cuts that rendered the development of a fully-reusable space shuttle infeasible. NASA administrator George Low lamented that shuttle development might have to be delayed until the 1980s, with "something like a "big G" approach and a cheap space station" filling in as an interim. The office of management and budget (OMB) was more favorable to the idea than NASA. They concluded in a staff paper that a Big Gemini launch aboard a modernized Titan III would be a more cost-effective option than any shuttle design. Ultimately, OMB Deputy Director Caspar Weinberger helped to broker a compromise where Big G was taken off the table, and they gave NASA the green light for the immediate development of a partially-reusable thrust-assisted orbiter shuttle.

Specifications

Crew size: 9 to 12
Length: 11.5 m (38 ft)
Maximum diameter: 4.27 m (14.0 ft)
Habitable volume: 18.7 m3 (660 cu ft)
Mass: 15,590 kg (34,370 lb)
Payload: 2,500 kg (5,500 lb)

Launch vehicles: Titan 3M, Saturn IB, Saturn S-IC/S-IVB.