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Soyuz spacecraft
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Soyuz; English: Union) is a series of spacecraft designed for the Soviet space program by the Korolyov Design Bureau. The Soyuz succeeded the Voskhod spacecraft and was originally built as part of the Soviet Manned Lunar program. The first unmanned Soyuz mission was launched November 28, 1966; the first Soyuz mission with a crew was launched April 23, 1967, but the cosmonaut on board died during the flight's crash-landing. The first Soyuz flight which the crew survived was launched October 26, 1968.
Currently, the Soyuz spacecraft family is still in service and has launched more human spaceflight missions than any other platform. The Soyuz spacecraft is launched by the Soyuz launch vehicle, as part of the Soyuz program and in the later missions as part of the Zond program. They were later used to carry cosmonauts to and from Salyut and later Mir Soviet space stations, and are now used for transport to and from the International Space Station.
Design
A Soyuz spacecraft consists of three parts (from front to back):
The first and third modules are single-use and destroyed upon re-entry in the atmosphere. 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 is both larger and lighter than the 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.
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; Bytovoi otsek (BO)) also known as Habitation section. It houses all the equipment that will not be needed for reentry, such as experiments, cameras or cargo. The 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, the astronauts enter 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; Spuskaemyi 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 thought up at a time when nearly every headlight was circular.
Service Module (PAO)At the back of the vehicle is the service module; Priborno-Agregatnyi Otsek (PAO)). It has a pressurized container shaped like a bulging can (Instrumentation compartment, PO (Priborniy Otsek) that contains systems for temperature control, electric power supply, long-range radio communications, radio telemetry, instruments for orientation and control. A non-pressurized part of the service module (Propulsion compartment, AO (Agregatniy Otsek)) 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 (PkhO or Perekhodnoi Otsek). 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.
Re-Entry Procedure Because its modular construction differs from that of previous designs, the Soyuz has an unusual sequence of events prior to re-entry. The spacecraft is turned engine-forward and the main engine is fired for de-orbiting fully 180° ahead of its planned landing site. This requires the least propellant for re-entry, the spacecraft traveling on an elliptical Hohmann orbit to a point where it will be low enough in the atmosphere to re-enter.
Early Soyuz spacecraft would then have the service and orbital modules detach simultaneously. As they are connected by tubing and electrical cables to the descent module, this would aid in their separation and avoid having the descent module alter its orientation. Later Soyuz spacecraft detach the orbital module before firing the main engine, which saves even more propellant, enabling the descent module to return more payload. But in no case can the orbital module remain in orbit as an addition to a space station, for the hatch enabling it to function as an airlock is part of the descent module.
Re-entry firing is done on the "dawn" side of the earth, so that the spacecraft can be seen by recovery helicopters as it descends in the evening twilight, illuminated by the sun when it is above the shadow of the Earth. The Soyuz craft is designed to come down on land, usually somewhere in the deserts of Kazakhstan in central Asia. This is in contrast to early US manned missions which "splashed down" in the ocean.
Spacecraft systems - Thermal Control System - Sistema Obespecheniya Teplovogo Rezhima, SOTR
- Life Support System - Kompleks Sredstv Obespecheniya Zhiznideyatelnosti, KSOZh
- Power Supply System - Sistema Elektropitaniya, SEP
- Communication and Tracking Systems - Rassvet (Dawn) radio communications system, Onboard Measurement System (SBI), Kvant-V spacecraft control, Klyost-M television system, Orbit Radio Tracking (RKO)
- Onboard Complex Control System - Sistema Upravleniya Bortovym Kompleksom, SUBK
- Combined Propulsion System - Kompleksnaya Dvigatelnaya Ustanovka, KDU
- Chaika-3 Motion Control System (SUD)
- Optical/Visual Devices (OVP)- VSK-4 (Vizir Spetsialniy Kosmicheskiy-4),Night Vision Device (VNUK-K, Visir Nechnogo Upravleniya po Kursu), Docking light, Pilot's Sight (VP-1, Vizir Pilota-1), Laser Range Finder (LPR-1, Lazerniy Dalnomer-1)
- Kurs rendezvous system
- Docking System - Sistema Stukovki i Vnutrennego Perekhoda, SSVP
- Teleoperator Control Mode - Teleoperatorniy Rezhim Upravleniya, TORU
- Entry Actuators System - Sistema Ispolnitelnikh Organov Spuska, SIO-S
- Landing Aids Kit - Kompleks Sredstv Prizemleniya, KSP
- Portable Survival Kit - Nosimiy Avariyniy Zapas, NAZ, containing a TP-82 or other pistol
- Soyuz Launch Escape System - Sistema Avariynogo Spaseniya, SAS
Variants
The Soyuz spacecraft has been the subject of continuous evolution since the early 1960s. Thus several different actual versions, proposals and projects exist.
Technical Data Soyuz A (part of the "circumlunar complex") (1963)Korolyov initially promoted the Soyuz A-B-C circumlunar complex (7K-9K-11K) concept (also known as L1) in which a two-man craft Soyuz-A 7K would rendezvous with other components (9K and 11K) in Earth orbit to assemble a lunar excursion vehicle, the components being delivered by the proven R-7 rocket.
First generationThe manned Soyuz spacecraft can be classified into design generations. Soyuz 1 through Soyuz 11 (1967-1971) were first-generation vehicles, carrying a crew of up to three without spacesuits and distinguished from those following by their bent solar panels and their use of the Igla automatic docking navigation system, which required special radar antennas. This first generation was called Soyuz 7K-OK and encompassed the original Soyuz and Salyut 1 Soyuz.
The Soyuz 7K-L1 was designed to launch men from the Earth to circle the moon, and was the primary hope for a Soviet circumlunar flight. It had several test flights in the Zond program from 1967-1970, which produced multiple failures in the 7K-L1's re-entry systems. So the remaining 7K-L1s were scrapped. The Soyuz 7K-L3 was designed and developed in parallel to the Soyuz 7K-L1, but was also scrapped.
The next manned version of the Soyuz was the Soyuz 7K-OKS. It was designed for space station flights and had a docking port that allowed internal transfer between spacecraft. The Soyuz 7K-OKS had two manned flights, both in 1971, and the second of which depressurized upon re-entry, killing its three-man crew.
Second generationThe second generation, called Soyuz Ferry or Soyuz 7K-T, comprised Soyuz 12 through Soyuz 40 (1973-1981). It was developed out of the military Soyuz concepts studied in previous years. The Soyuz 7K-T/A9 version was used for the flights to the military Almaz space station.
Soyuz 7K-TM was the spacecraft used in the Apollo-Soyuz Test Project in 1975, which saw that first and only docking of a Soyuz spacecraft with an Apollo spacecraft. It was also flown in 1976 for the earth-science mission, Soyuz 22. Soyuz 7K-TM served as a technological bridge to the third generation, the Soyuz-T spacecraft.
Several Military Soyuz models were planned, but none actually flew in space. These versions were named Soyuz 7K-P, Soyuz 7K-PPK, Soyuz R, Soyuz 7K-VI, and Soyuz OIS (Orbital Research Station).
Third generationThe third generation Soyuz-T (T - ????????????, Transportnyi meaning transport) spacecraft (1976-1986) featured solar panels allowing longer missions, a revised Igla rendezvous system and new translation/attitude thruster system on the Service module. It could carry a crew of three, now wearing spacesuits.
Fourth generationThe Soyuz-TM crew transports (M - ????????????????, Modifitsirovannyi meaning modified) were fourth generation Soyuz spacecraft, and were used from 1986 to 2003 for ferry flights to Mir and the International Space Station.
Soyuz-TMA (2003-.... )Soyuz TMA (A - ??????????????????, - Antropometricheskii meaning anthropometric) features several changes to accommodate requirements requested by NASA in order to service the International Space Station, including more latitude in the height and weight of the crew and improved parachute systems. It is also the first expendable vehicle to feature "glass cockpit" technology. Soyuz-TMA looks identical to a Soyuz-TM spacecraft on the outside, but interior differences allow it to accommodate taller occupants with new adjustable crew couches.
Soyuz TMAT (2009/....)In 2004, Russian space officials announced that the Soyuz will be replaced by early 2011 with the new Kliper and Parom spacecrafts. However, since then the Kliper appears to have been indefinitely postponed due to lack of funding from government, and it has been announced that the Soyuz will receive an upgrade to make it suitable for up to one year in space, as well as new digital interior displays and updated docking equipment. This new version, known as Soyuz TMAT, could enter service around 2008/9.
Soyuz ACTS (2012/....)Soyuz ACTS (Advanced Crew Transportation System), also known as Soyuz-K, is a proposed version of the Soyuz design capable of achieving lunar orbit. The upgrades could include a new habitation module developed by the European Space Agency. Missions could be launched from Baikonur or Guiana Space Centre.
Related craftThe unmanned Progress spacecraft were derived from Soyuz and are used for servicing space stations.
The Chinese Shenzhou spacecraft is also heavily influenced by the design of the Soyuz.
Operators
See also
MissionsSee List of Soviet and Russian manned space missions as well as the Zond program
Image gallery
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