Advanced Gemini

Other modifications considered included the addition of wings or a parasail to the spacecraft, in order to enable it to make a horizontal landing.

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.

In the case of the Manned Orbital Laboratory, a Gemini spacecraft was launched on a suborbital demonstration flight in support of the program.

[5] 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.

Gemini B was released on a suborbital trajectory, and descended to Earth to test modifications made to the heat shield, and ensure that the access hatch would not affect its performance.

Later stations would have been designed to be resupplied, and support multiple crews, delivered by additional Gemini spacecraft, or derivatives.

[6] Several Gemini Ferry spacecraft were proposed to provide transportation of crews and cargo to NASA and USAF space stations in low Earth orbit.

NASA contracted McDonnell to conduct a study into what modifications would be needed to allow the Gemini spacecraft to support this.

[9] Changes that would have been required included strengthening the nose, installing two solid rockets to be used for a separation burn, adding the necessary equipment to perform the transfer EVA, and providing provisions for flight to and from the station.

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.

Many of the proposals made for this involved a double-launch architecture, with the Gemini spacecraft rendezvousing with an upper stage in orbit.

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.

[13] The Gemini spacecraft would have rendezvoused with stacked Centaur and Agena upper stages in low Earth orbit.

[15] The initial proposal was for a Lunar orbit rendezvous mission, using a Gemini spacecraft and a lightweight, open cockpit lander, launched by a Saturn C-3 rocket.

[15] The spacecraft would have been tested in Low Earth orbit before the Lunar missions, using two Titan II launches.

The Reentry Module was based on the Gemini capsule, but would have been modified to allow it to reenter the atmosphere at the higher velocity that would have been required by a lunar flight.

[16] It was seen as the last effort by NASA managers and engineers who still advocated the direct ascent mission profile, and was intended to be cheaper, faster and safer than the Apollo lunar orbit rendezvous technique.

[16] Due to the risks associated with the Lunar landing, several rescue spacecraft were proposed, to be used to allow the crew of an Apollo mission to return to Earth safely in the event of a problem.

[18] Launch and trans-Lunar injection would have been performed by a Saturn V. Once the spacecraft was in Lunar orbit, the Apollo crew would have boarded it by means of an EVA.

[18] Another proposed spacecraft, the Gemini Lunar Surface Survival Shelter, was designed to be sent to the Moon ahead of an Apollo mission.

[19] It consisted of a Gemini Reentry Module, which would have housed the astronauts while they awaited rescue, and a descent stage containing life support systems, consumables, and the engine and propellant used to land the spacecraft.

[19] The Gemini Lunar Surface Rescue Spacecraft[17] was intended to fly a direct ascent mission, launched by a Saturn V. Descent stages, built from either the descent stage of the Apollo Lunar Module, or from the Apollo Service Module, would have reduced the spacecraft's velocity as it approached the Moon.

It would have launched atop a Titan IIIC, once in orbit it would have maneuvered by means of a Transtage integrated into the equipment module.

[22] Another proposed mission would have seen a Gemini spacecraft rendezvous with a Pegasus satellite in low Earth orbit.

The Gemini would have flown around the Pegasus, and then one of the crew would have performed an EVA to recover a piece of one of the spacecraft's micrometeoroid detection panels.

The spacecraft had originally been designed to land using a flexible Rogallo wing and a set of skis or wheels,[24] however this was abandoned in favor of splashdowns under parachutes due to delays in development and failures during testing.

[28] This proposal arose soon after the cancellation of the X-20 Dyna-Soar, and would have seen a Gemini spacecraft attached to a set of wings developed during the ASSET program.

[28] There were also proposals to use the Gemini spacecraft to conduct long-duration missions to small, purpose-built space stations in low-Earth orbit.