Advanced Gemini

Advanced Gemini is a number of proposals that would have extended the Gemini program by the addition of various missions, including manned low Earth orbit, circumlunar and lunar landing missions. Gemini was the second manned spaceflight program operated by NASA, and consisted of a two-seat spacecraft capable of maneuvering in orbit, docking with unmanned spacecraft such as Agena Target Vehicles, and allowing the crew to perform tethered extra-vehicular activities.

A range of applications were considered for Advanced Gemini missions, including military flights, space station crew and logistics delivery, and lunar flights. The Lunar proposals ranged from reusing the docking systems developed for the Agena target vehicle on more powerful upper stages such as the Centaur, which could propel the spacecraft to the Moon, to complete modifications of the Gemini to enable it to land on the Lunar surface. Its applications would have ranged from manned lunar flybys before Apollo was ready, to providing emergency shelters or rescue for stranded Apollo crews, or even replacing the Apollo program.

Some of the Advanced Gemini proposals used "off-the-shelf" Gemini spacecraft, unmodified from the original program, whilst others featured modifications to allow the spacecraft to carry more crew, dock with space stations, visit the Moon, and perform other mission objectives. Other modifications considered included the addition of wings or a parasail to the spacecraft, in order to enable it to make a horizontal landing.

Gemini was the second American manned orbital spaceflight program, after Mercury. It was intended to demonstrate technologies and techniques required for the Apollo program, such as extra-vehicular activities, rendezvous and docking, maneuvering in orbit and long duration flight.

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