The Soyuz-TMA (Russian: транспортный модифицированный антропометрический, romanized: Transportnyi Modifitsirovannyi Antropometricheskii, lit. 'Transport Modified Anthropometric') was a spacecraft built by Energia and used by Roscosmos for human spaceflight. It is a revision of the Soyuz spacecraft introduced in 2001 and was in use until 2012 after being superseded in 2010 by the Soyuz TMA-M. While it looks identical to the earlier Soyuz-TM on the outside, the spacecraft features several changes to accommodate requirements requested by NASA to better service the International Space Station. The most important difference are the anthropometric changes, primarily in the form of new adjustable crew couches that allowed shorter, taller, lighter and heavier passengers to ride in the spacecraft. The Soyuz also received improved parachute systems and a "glass cockpit," a first for an expendable vehicle.
Design
A Soyuz spacecraft consists of three parts (from front to back):
A spheroid orbital module A small aerodynamic reentry module A cylindrical service module with solar panels attached The first two portions are habitable living space. By moving as much as possible into the orbital module, which does not have to be shielded or decelerated during atmospheric re-entry, the Soyuz three-part craft is both larger and lighter than the two-part Apollo spacecraft's command module. The Apollo command module had six cubic meters of living space and a mass of 5000 kg; the three-part Soyuz provided the same crew with nine cubic meters of living space, an airlock, and a service module for the mass of the Apollo capsule alone. This does not consider the orbital module, that could be used instead of the Apollo Lunar Module. Soyuz can carry up to three cosmonauts and provide life support for them 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.
Orbital Module (BO)
The forepart of the spacecraft is the orbital module ((in Russian): бытовой отсек (BO), Bitovoy otsek) also known as Habitation section. It houses all the equipment that will not be needed for reentry, such as experiments, cameras or cargo. Commonly, it is used as both eating area and lavatory. At its far end, it also contains the docking port. This module also contains a toilet, docking avionics and communications gear. On the latest Soyuz versions, a small window was introduced, providing the crew with a forward view. A hatch between it and the descent module can be closed so as to isolate it to act as an airlock if needed, cosmonauts exiting through its side port (at the bottom of this picture, near the descent module) on the launch pad, they have entered the spacecraft through this port. This separation also lets the orbital module be customized to the mission with less risk to the life-critical descent module. The convention of orientation in zero gravity differs from that of the descent module, as cosmonauts stand or sit with their heads to the docking port.
Reentry Module (SA)
The reentry module ((in Russian): спускаемый аппарат (СА), Spuskaemiy apparat (SA)) is used for launch and the journey back to Earth. It is covered by a heat-resistant covering to protect it during re-entry. It is slowed initially by the atmosphere, then by a braking parachute, followed by the main parachute which slows the craft for landing. At one meter above the ground, solid-fuel braking engines mounted behind the heat shield are fired to give a soft landing. One of the design requirements for the reentry module was for it to have the highest possible volumetric efficiency (internal volume divided by hull area). The best shape for this is a sphere, but such a shape can provide no lift, which results in a purely ballistic reentry. Ballistic reentries are hard on the occupants due to high deceleration and can't be steered beyond their initial deorbit burn. That is why it was decided to go with the "headlight" shape that the Soyuz uses — a hemispherical forward area joined by a barely angled conical section (seven degrees) to a classic spherical section heat shield. This shape allows a small amount of lift to be generated due to the unequal weight distribution. The nickname was coined at a time when nearly every automobile headlight was a circular paraboloid.
Service Module (PAO)
At the back of the vehicle is the service module ((in Russian): приборно-агрегатный отсек, Priborno-Agregatniy Otsek (PAO)). It has an instrumentation compartment ((in Russian): приборный отсек, Priborniy Otsek (PO)), a pressurized container shaped like a bulging can that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, and instruments for orientation and control. The propulsion compartment ((in Russian): агрегатный отсек, Agregatniy Otsek (AO)), a non-pressurized part of the service module, contains the main engine and a spare: liquid-fuel propulsion systems for maneuvering in orbit and initiating the descent back to Earth. The ship also has a system of low-thrust engines for orientation, attached to the intermediate compartment ((in Russian): переходной отсек, Perekhodnoi Otsek (PkhO)). Outside the service module are the sensors for the orientation system and the solar array, which is oriented towards the Sun by rotating the ship.
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