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Gemini B
Part of Gemini Family
American manned spacecraft. Cancelled 1969. Gemini was extensively redesigned for the MOL Manned Orbiting Laboratory program. The resulting Gemini B, although externally similar, was essentially a completely new spacecraft.

Gross mass: 1,983 kg (4,371 lb). Height: 3.35 m (10.99 ft). Diameter: 2.32 m (7.61 ft).

Gemini B was not designed to fly separately, but rather was launched with the crew aboard attached to the manned orbiting laboratory. After reaching orbit, the crew would shut down the capsules systems and put them into hibernation. They would crawl through an 0.635 m diameter hatch in the heat shield, leading to a tunnel that accessed the MOL itself. After thirty days of operations, the crew would return to the Gemini B, separate from the MOL, and reenter the atmosphere. Gemini B had only 14 hours of 'loiter capability' for autonomous operations after separation from the MOL.

Many changes were made from the original NASA Gemini, including:

  • Internal systems were containerized and designed for long term orbital storage
  • The cockpit layout was completely redesigned and new instruments were developed
  • The cant of the ejection seats were changed in order to make room for the hatch in the heat shield between the crew's shoulders
  • After the Apollo fire, cabin atmosphere was changed to Helium-Oxygen in place of pure oxygen. At launch, the crew breathed pure oxygen in their suits while the cabin was filled with pure helium. During ascent, oxygen from the suits slowly brought the cabin atmosphere up to the helium-oxygen content of the station itself.
  • In order to handle higher energy re-entries from polar orbit, the heat shield was increased in diameter, so that it actually stuck out a bit from the base of the re-entry vehicle.
  • The OAMS maneuvering thrusters of the NASA Gemini were deleted. Spacecraft orientation in orbit was handled by the forward RCS thrusters.

Gemini B would have been flown alone, without an active MOL, unmanned, in two qualification test launches of the Titan 3M booster prior to the first manned MOL flight.

Changes to the Gemini adapter module included:

  • A transition tunnel led from the hatch in the heat shield of the Gemini B to the MOL pressurized quarters.
  • In the absence of the equipment module, the adapter module was longer in order to flare out to meet the 3.05 m diameter of the MOL.
  • The OAMS maneuvering thrusters of the NASA Gemini were deleted. Spacecraft orientation in orbit was handled by the forward RCS thrusters.
  • The number of solid propellant retrofire motors was increased from four to six. These served double-duty: for deorbit of the Gemini B and as abort rockets for separation of the Gemini from the enormous Titan 3M in case of launch vehicle failure.



Country: USA.

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