Crew Return Vehicle - Soyuz TMA

Soyuz TMA

With the cancellation of the X-38 and CRV programs in 2001, it was clear that the interim use of Soyuz capsules would be a longer term necessity. To make them more compatible with the needs of the ISS, Energia was contracted to modify the standard Soyuz TM capsule to the TMA configuration. The main modifications involve the interior layout, with new, improved seats to accommodate larger American astronaut anthropometric standards. A series of test drops of the improved capsule were made in 1998 and 1999 from an Ilyushin Il-76 cargo plane to validate the landing capabilities of the TMA.

A Soyuz-TMA capsule is always attached to the ISS in "standby" mode, in case of emergencies. Operated in this configuration, the TMA has a lifespan of about 200 days before it has to be rotated out, due to the degradation of the hydrogen peroxide used for its reaction control system. Because of this limitation, the vehicle is planned for a typical six-month changeout cycle. The first flight of the TMA to the ISS occurred on October 29, 2002 with the flight of the Soyuz TMA-1.

Because the TMA is limited to three occupants, the ISS was also likewise restricted to that number of occupants, which drastically reduces the amount of research that can be done on board the ISS to 20 person-hours per week, far lower than what was anticipated when the station was designed. With Expedition 20 in May 2009, the crew size of the ISS was increased from 3 to 6 persons with the simultaneously docked two Soyuz spacecrafts.