The modified Soyuz TMA crewed spacecraft for transporting Crews to the ISS has been developed on the
basis of a Soyuz TMA spacecraft. In the new version, the
Argon-16 computer (introduced on Soyuz-T back in the 1970s) is
replaced by the new TsVM-101 computer. The latter is a much more capable computer, is
almost 10 times lighter (8.3 kg vs. 70 kg) and much smaller. The analogue telemetry system
is also replaced by a smaller digital telemetry system called MBITS.
It is to provide rescue of the main crew of the station in emergency and delivery of
visiting crews.
During the flight the spacecraft fulfills the following tasks:
- delivery of a visiting crew consisting of up to three persons and small accompanying
cargoes
- constant availability of the spacecraft, attached to the station during its crewed
flight, in the standby mode to be ready for emergency descent of the main crew onto the
ground in case of hazardous situation on the station, cosmonaut illness or injury, etc.
(assured crew return vehicle function);
- planned descent of the visiting crew onto the ground;
- returning to the ground, together with the crew, payloads of relatively low mass and
volume
- disposal of wastes from the station in the living compartment to be burned down in the
atmosphere during descent.
During a pressure test, the descent module of vehicle №704 was damaged beyond repair. The descent module was replaced with the one, which was originally planned to be used in vehicle №707. This repaired vehicle received the serial number №704A and flew on the Soyuz-TMA 07M mission.
During the missions of both Soyuz-TMA 14M and Soyuz-TMA 17M, one of the solar arrays remained stuck after launch and deployed only during the docking with the ISS.
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