Advanced Gemini is a number of proposals that would have extended the Gemini program by the addition of various missions, including crewed low Earth orbit, circumlunar and lunar landing missions. Gemini was the second crewed spaceflight program operated by NASA, and consisted of a two-seat spacecraft capable of maneuvering in orbit, docking with uncrewed 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 crewed 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, while 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.
Background
Gemini was the second American crewed 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.
The Gemini spacecraft, which was built by McDonnell Aircraft, was derived from the earlier Mercury spacecraft, but modified to accommodate two astronauts. It was also equipped with a larger equipment module, allowing it to support longer missions, and maneuver in orbit. It was launched by the Titan II rocket flying from Launch Complex 19 at the Cape Canaveral Air Force Station. In total, twelve missions were launched, ten of which were crewed. Following two uncrewed test flights, the first crewed flight, Gemini 3, was launched on 23 March 1965. The program concluded on 15 November 1966, with the successful recovery of Gemini 12.
Many other applications were envisaged for the Gemini spacecraft at various stages before, during, and after the two years in which it was used by NASA for crewed spaceflight. Although none of these proposals ever made it into operation, many were considered seriously, and in some cases flight hardware was constructed prior to cancellation. In the case of the Manned Orbital Laboratory, a Gemini spacecraft was launched on a suborbital demonstration flight in support of the program. In some cases technology developed in the Advanced Gemini program has been reintegrated into other programs, such as components from the Titan IIIM, which was to have launched MOL, being used to upgrade other Titan rockets.
Military applications
The United States Air Force intended to use the Gemini spacecraft to transport astronauts to its proposed space stations, the Manned Orbital Development System and later the Manned Orbital Laboratory (MOL). These stations would have been launched by Titan IIIM rockets, with a Gemini spacecraft atop, eliminating the need for rendezvous and docking maneuvers. For this purpose, several modifications were made to the Gemini capsule, including the installation of a hatch in the heat shield to allow access to the space station.
In order to give its astronauts experience before these programs started, the Blue Gemini program was proposed, which would have seen USAF astronauts fly on NASA missions in order to practice various techniques required for their own missions. This would have first seen cooperative missions between NASA and the US Air Force, with two missions flying with crews composed of one astronaut from NASA, and one from the USAF, followed by two missions with all-USAF crews, but performing missions for NASA. After these flights, the US Air Force would have flown a number of missions of its own. Firstly, it would have flown a two-man Agena rendezvous and docking mission, followed by two one-man scientific or technology research missions. Other proposed missions included tests of the Astronaut Mobility Unit which was designed to assist with EVAs, inertial navigation systems, and flying a radar imaging system.