Soyuz (spacecraft) - Design

Design

A Soyuz spacecraft consists of three parts (from front to back):

• A spheroid orbital module, which provides accommodation for the crew during their mission;
• A small aerodynamic reentry module, which returns the crew to Earth;
• A cylindrical service module with solar panels attached, which contains the instruments and engines.

The orbital and service modules are single-use and are destroyed upon re-entry in the atmosphere. The orbital and reentry portions are habitable living space. By moving as much equipment as possible into the orbital module, which does not have to be shielded or decelerated during atmospheric re-entry, the Soyuz is both larger and lighter than the contemporary Apollo spacecraft's command module. The Apollo command module had more than six cubic meters (6.2 m³) of living space and a mass of 5000 kg; the three-part Soyuz (command, orbital and service modules) provides the same crew (since the Soyuz T in 1980) with more than seven cubic meters of living space (5 m³ in OM, plus 2.5 m³ in RM), an airlock, and a service module for the mass of the Apollo capsule alone (mass of empty Soyuz was 5600 kg). On the other hand Apollo was operating with three astronauts in spacesuits and was able to land with five astronauts in spacesuits in 1973 (prepared rescue mission for second Skylab crew), Soyuz was for two cosmonauts in spacesuits in the 1960s and 1970s, and for three since 1980 (Soyuz T). On nine Apollo missions (9 through 17) the astronauts also had access to the Lunar Module, which added 6.7 cubic metres of volume but also another 2200 kg of mass (if counting just the empty ascent stage as being somewhat equivalent to the Soyuz orbital module, although including empty fuel tanks, engine and RCS system — 14700 kg when including the descent stage and fuel).

Soyuz can carry up to three crew members and provide life support for about 30 person days. The life support system provides a nitrogen/oxygen atmosphere at sea level partial pressures. The atmosphere is regenerated through KO₂ cylinders, which absorb most of the CO₂ and water produced by the crew and regenerates the oxygen, and LiOH cylinders which absorb leftover CO₂.

The vehicle is protected during launch by a nose fairing, which is jettisoned after passing through the atmosphere. It has an automatic docking system. The ship can be operated automatically, or by a pilot independently of ground control.