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Descent Module, SA, of the Soyuz spacecraft
Crew inside the descent module of the Soyuz MS-05 spacecraft.
The reentry capsule of the Soyuz spacecraft is known by its Russian acronym "SA" for "spuskaemy apparat" (descent apparatus). It is the only section of the vehicle, which returns to Earth at the end of the mission.
The Descent Module contains two or three personally contoured couches where the cosmonauts recline for ascent, descent and landing. Seats are facing controls and displays developed at OAO Fazotron-NIIR that are used for all critical flight activities.
The reentry capsule also contains life-support systems, batteries for the descent phase of the mission, primary and backup parachutes and solid-propellant engines for landing. The reentry capsule is also equipped with eight small attitude control thrusters, which are used exclusively during the descent phase of the flight. They use hydrogen peroxide as a one-component propellant which doesn't need oxidizer. However, the tendency of peroxide to degrade over time is considered as a limiting factor for the duration of the Soyuz missions normally planned for no more than six months.
The reentry capsule is also equipped with an independent guidance, navigation and control system that is less complex than the main system in the PAO module.
A periscope extending from the reentry capsule provides the pilot with a forward view toward the docking mechanism and a downward view for tracking the surface of the Earth.
Catherine Coleman, a member of Soyuz TMA-20 crew, inside the descent module, looking toward the right side of the capsule. The main flight control panel, sporting liquid-crystal displays is on the left. Credit: Roskosmos
Above: Members of Soyuz TMA-20 crew, Dmitry Kondratyev (left) and Paolo Nespoli inside the descent module, looking toward the left side of the capsule. Credit: Roskosmos
Known technical specifications of the reentry capsule of the Soyuz spacecraft:
The reentry capsule of the Soyuz-3 spacecraft. The cover of the parachute container is in the foreground. The opening of the parachute container can be seen on the left side of the capsule. Copyright © 2001 Anatoly Zak
The reentry capsule of the Soyuz spacecraft. The entry hatch is in front. Two hatches of the parachute containers are on top. Copyright © 2001 Anatoly Zak
Bottom of the Soyuz reentry capsule, without its heat shield. Copyright © 2001 Anatoly Zak
A dissected Soyuz reentry vehicle (left) and habitable section (partially visible). Copyright © 2000 Anatoly Zak
A parachute container of the Soyuz spacecraft. Copyright © 2001 Anatoly Zak