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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Advanced Gemini | 3/5 | https://en.wikipedia.org/wiki/Advanced_Gemini | reference | science, encyclopedia | 2026-05-05T12:50:41.219775+00:00 | kb-cron |
Big Gemini, or Big G, grew out of a 1963 proposal called Gemini Transport, to develop an enlarged Gemini spacecraft with docking capability, which would take advantage of the increased capacity offered by the Saturn IB and Titan IIIM rockets. It was designed to transport between nine and twelve astronauts into space, and to be able to dock with space stations, in support of Apollo Applications and MOL missions. It would have been launched by a Heavy lift launch vehicle; 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, which would have launched a smaller version of the spacecraft due to 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. The shape and mass of the spacecraft would have varied depending on the rocket that was to launch it. The Saturn-launched version had a short, conical cargo module, and a total mass of 47,300 kilograms (104,300 lb) whereas 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. Use of 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 in turn mounted on the rear of the re-entry module. The re-entry module itself would have been enlarged to accommodate the larger crew, and the modifications made to the spacecraft for the MOL program would have been incorporated, including the hatch in the heat shield, which would have been used to provide 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. Big G would have made landings on land, using a parasail or paraglider to guide it onto a runway or dry lake, such as the one at Edwards Air Force Base. It would have landed using skids derived from the North American X-15.
== Lunar exploration ==
=== Circumlunar missions ===
Studies investigated sending a Gemini spacecraft onto a circumlunar trajectory. Many of the proposals made for this involved a double-launch architecture, with the Gemini spacecraft rendezvousing with an upper stage in orbit. Upper stages that were considered included the Transtage, the second stage of a Titan II, four different types of Centaur, including the S-V variant developed for the Saturn I, the Agena-D, an enlarged Agena, and two Agenas burning in parallel. Either a Titan or Saturn IB would have been used to launch the upper stage, while the Gemini would launch on the Titan II, as it had in the Gemini program. Other proposals involved launching the Gemini spacecraft on a Titan IIIC, and refueling in low Earth orbit before proceeding to the Moon, and a single launch architecture using a three-stage variant of the Saturn IB. The Gemini-Centaur proposal was predicted to have been able to achieve a 72-hour circumlunar flight. The Centaur would have performed trans-lunar injection, before separating from the Gemini spacecraft. Some concerns were raised that the Gemini spacecraft's heat shield would not have been able to protect it during the higher speed ballistic reentry associated with the trajectory that would have been required. NASA proposed using a thicker heat shield and more insulation to protect the spacecraft. This and several other modifications made the spacecraft too heavy to be launched by the Titan II rocket which was used for the original twelve Gemini missions, so several solid rocket motors would have been added to allow this additional mass to be flown.
=== Lunar orbit missions === The Gemini spacecraft would have rendezvoused with stacked Centaur and Agena upper stages in low Earth orbit. The Centaur would have placed the Gemini and Agena onto a circumlunar trajectory, along which they would coast until they reached the Moon. The Agena would then have been used to perform Lunar orbit insertion. Following the completion of activities in Lunar orbit, the Agena would have been fired again for trans-Earth injection. This architecture would have used a Titan II to launch the Gemini spacecraft, with a Saturn IB launching the upper stages.
=== Lunar landing ===