space station

A complex physical structure specifically designed to serve as a multipurpose platform in low Earth orbit. Functioning independently and often without a crew, a space station contains the structures and mechanisms to operate and maintain such support systems as command and data processing, communications and tracking, motion control, electrical power, and thermal and environmental control. Evolving together with technology and increasing in scope and complexity, the space station has a history in which each program was based upon the developments and achievements of its predecessor.

Salyut

The Soviet Union began construction of the world's first space station, called Salyut, in 1970. It was the primary Soviet space endeavor for the next 15 years. The design was retained not only through a series of Salyuts that were launched within that decade and later, but also through the development of Mir, the most famous, long-lived Russian achievement in space. The Salyuts were cylindrical in shape and contained compartments with specialized functions for operating a space station. The docking compartment was designed to accept the Soyuz spacecraft that transported the cosmonauts. The transfer compartment gave the cosmonauts access to the various work compartments. The work compartments contained the mechanisms that operated and controlled the station, as well as the laboratories in which the cosmonauts performed experiments while they were onboard. Salyut 1 initially carried a crew of three, but after three cosmonauts died when a valve in the crew compartment of their descent module burst and the air leaked out, the crews were reduced to two cosmonauts, and both crew members were outfitted with pressurized space suits.

Skylab

This program was developed by NASA building on the success of its heavy-lift rocket, the Saturn, which had boosted the Apollo rockets and helped place the first human being on the Moon. Skylab weighed just less than 100 tons (90 metric tons). It was launched on May 14, 1973, from the Kennedy Space Center aboard a Saturn 5 rocket. Although the launch was flawless, a shield designed to shade Skylab's workshop deployed about a minute after liftoff and was torn away by atmospheric drag. That began a series of problems, most involving overheating, that had to be overcome before Skylab was safe for human habitation. Eventually three crews served aboard Skylab throughout 1973 for periods of 28, 59, and 84 days, respectively. The single greatest contribution made by each crew was the extravehicular activities that restored Skylab's ability to serve as a space station.

Apollo-Soyuz test program

In 1975, during the period of dètente, plans were made for a joint United States-Soviet space venture, known as the Apollo-Soyuz Test Program (ASTP). For the first time, United States astronauts and Soviet cosmonauts became members of each other's flight teams, training together, touring their launch sites, and working in their mission control rooms. For 15 months, they trained and prepared for their historical joint mission in space. In July 1975, the astronauts of Apollo 18 linked with the cosmonauts of Soyuz 22; their docked configuration functioned as a miniature international space station.

Mir

Mir was the name of the vehicle for the world's first multipurpose, permanently operating crewed space station. Based upon the Salyut design and configuration, Mir essentially was an extension and expansion of the shell of the basic Soviet space vehicle. It would incorporate the standard Salyut/Soyuz/Progress profile. External ports were added for docking of Soyuz vehicles which would carry crew members, and Progress (resupply) vehicles which would bring foodstuffs, drinking water, extra equipment and apparatus, sanitary requisites, medical apparatus, and propellant. These same Progress vehicles would return space “junk” to Earth. Construction was based upon a modular design, permitting the Soviets to replace modules whenever significant improvements in technology made the earlier modules obsolete. Two cylindrical modules formed the basic shape of Mir and served as the living and central control compartments for the crews. Additional modules were used for scientific experiments.

The Mir core station was a 49-ft (15-m) module. Its launch aboard a Soviet Proton rocket on February 20, 1986, was televised internationally for the first time in Soviet space history. Mir was assembled in space and was composed of six modules. In addition to the core, the Kvant-1 module (launched in April 1987) was a 19-ft (6-m) pressurized lab used for astrophysics research. The Kvant-2 module was launched in December 1989, and was used for biological research and for Earth observation. The Kristall module was launched in August 1990, and provided the docking port for the United States space shuttles that visited Mir. Between 1994 and 2001, there were nine dockings between space shuttle vehicles and Mir. The final two modules, Spektr and Priroda (launched in June 1995 and April 1996, respectively) were remote sensing modules used to study the Earth. Mir provided a platform for long-term microgravity research and increased knowledge about living and working in space. By the end of its function in March 2001, the 143-ton (130-metric-ton) Mir had spent 15 years in orbit and had orbited the Earth more than 87,600 times with an average orbiting speed of 17,885 mi/h (28,800 km/h). Its superstructure, 109 ft (33 m) long and 90 ft (27 m) wide, burned up upon reentry in to the Earth's atmosphere, and scraps were scattered into the Pacific Ocean just east of New Zealand. See also Space biology; Space shuttle.

International Space Station

The Soviet successes with Mir prompted the United States to respond with what became known as Space Station Freedom. Moved from the NASA drawing board in 1993, components of the space station were tested by shuttle crews during a variety of missions. Supporters of this space station advocated such unique opportunities as manufacturing drugs, scientific materials research in microgravity, and studying the health and status of the Earth's environment from outer space. At the direction of President Clinton, the United States transformed the single-nation concept for Space Station Freedom into a multinational partnership with the European Space Agency and the Russian Space Agency to create what is now known as the International Space Station (ISS). See also Space processing.

Sixteen nations have united to build the International Space Station. Dwarfing Mir, Skylab, the Salyuts, and any ground-based civil engineering project built to date, the International Space Station will include six laboratories built by a consortium of nations. United States space shuttle and Russian Soyuz flights will transport the structures and mechanisms necessary to construct the station.

The first permanent crew of the International Space Station launched from the Baikonur Cosmodrome, on October 31, 2000. In addition to serving as a test bed and springboard for future space exploration, the International Space Station will serve as a research laboratory for innovation in science and technology. Research will focus on such topics as biomedical research and countermeasures to understand and control the effects of space and zero gravity on crew members; biological study of gravity's influence on the evolution, development, and internal processes of plants and animals; biotechnology to develop superior protein crystals for drug development; and fluid physics. Advanced research will be oriented toward topics such as human support technology, materials science, combustion science, and fundamental physics. See also Space flight; Space technology; Spacecraft structure.

A proposed structure to be built in space by NASA in the 1990s. The space station would be a permanent habitat at which scientific and technological work could be carried out. Building a space station is considered the next step in the development and exploration of space.

(click to enlarge)
Soviet/Russian space station Mir, after completion in 1996. The date shown for each module is its … (credit: Encyclopædia Britannica, Inc.)

Manned artificial structure designed to revolve in a fixed orbit as a long-term base for astronomical observations, study of Earth's resources and environment, military reconnaissance, and investigations of materials and biological systems in weightless conditions. As of 2001, nine space stations have been placed in a low Earth orbit and occupied for varying lengths of time. The Soviet Union orbited the world's first space station, Salyut 1, designed for scientific studies, in 1971. From 1974 to 1982 five more Salyut stations — two outfitted for military reconnaissance — were successfully placed in orbit and occupied. In 1986 the U.S.S.R. launched the core module of Mir, a scientific station that was expanded with five additional modules over the next decade. The U.S. orbited its first space station in 1973; called Skylab, it was equipped as a solar observatory and medical laboratory. In 1998 the U.S. and Russia began the in-orbit construction of the International Space Station (ISS), a complex of laboratory and habitat modules that would ultimately involve contributions from at least 16 countries. In 2000 the ISS received its first resident crew.

For more information on space station, visit Britannica.com.

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The International Space Station in July 2009.

A space station is an artificial structure designed for humans to live in outer space. To date, only low earth orbital (LEO) stations have been implemented, otherwise known as orbital stations. A space station is distinguished from other manned spacecraft by its lack of major propulsion or landing facilities—instead, other vehicles are used as transport to and from the station. Space stations are designed for medium-term living in orbit, for periods of weeks, months, or even years. The only space station currently in use is the International Space Station. Previous stations include the Almaz & Salyut series, Skylab and Mir.

Space stations are used to study the effects of long-term space flight on the human body as well as to provide platforms for greater number and length of scientific studies than available on other space vehicles. Since the ill-fated flight of Soyuz 11 to Salyut 1, all manned spaceflight duration records have been set aboard space stations. The duration record for a single spaceflight is 437.7 days, set by Valeriy Polyakov aboard Mir from 1994 to 1995. As of 2009^[update], three astronauts have completed single missions of over a year, all aboard Mir.

Contents 1 Uses 2 Types of space stations 2.1 Monolithic 2.2 Modular 3 Habitability issues 4 Architecture 5 Past and present space stations 5.1 List of occupied space stations, with statistics 6 Canceled space stations 7 Future developments 8 See also 9 References 10 Bibliography 11 External links

Uses

Space stations have been used for both military and civilian purposes. The last military-use space station was Salyut 5, which was used by the Almaz program of the Soviet Union in 1976 and 1977.^[1]

Types of space stations

Monolithic

Description of a space station in Hermann Noordung's The Problem of Space Travel (1929).
(Legend: Aufzugschacht: elevator shaft. K: electric cable to an external observatory. Kondensatorrohre: condenser pipes. S: airlock. Treppenschacht: stairwell. Verdampfungsrohr: boiler pipe).

Broadly speaking, the space stations so far launched have been of two types; the earlier stations, Salyut and Skylab, have been "monolithic", intended to be constructed and launched in one piece, and then manned by a crew later. As such, they generally contained all their supplies and experimental equipment when launched, and were considered "expended", and then abandoned, when these were used up.

Starting with Salyut 6 and Salyut 7, a change was seen; these were built with two docking ports, which allowed a second crew to visit, bringing a new spacecraft with them (for technical reasons, a Soyuz capsule cannot safely spend more than a few months in orbit, even powered down). This allowed for a crew to man the station continually. Skylab was also equipped with two docking ports, like second-generation stations, but the extra port was never utilized. The presence of a second port on the new stations allowed Progress supply vehicles to be docked to the station, meaning that fresh supplies could be brought to aid long-duration missions. This concept was expanded on Salyut 7, which "hard docked" with a TKS tug shortly before it was abandoned; this served as a proof-of-concept for the use of modular space stations. The later Salyuts may reasonably be seen as a transition between the two groups.

Modular

The second group, Mir and the ISS, have been modular; a core unit was launched, and additional modules, generally with a specific role, were later added to that. (On Mir they were usually launched independently, whereas on the ISS most are brought by the Space Shuttle). This method allows for greater flexibility in operation, as well as removing the need for a single immensely powerful launch vehicle. These stations are also designed from the outset to have their supplies provided by logistical support, which allows for a longer lifetime at the cost of requiring regular support launches.

Habitability issues

These stations have various issues that limit their long-term habitability, such as very low recycling rates, relatively high radiation levels and a lack of gravity. Some of these problems cause discomfort and long-term health effects. In the case of solar flares, all current habitats are protected by the Earth's magnetic field, and are below the Van Allen belts.

Future space habitats may attempt to address these issues, and are intended for long-term occupation. Some designs might even accommodate large numbers of people, essentially "cities in space" where people would make their homes. No such design has yet been constructed, since even for a small station, the current (2009) launch costs are not economically or politically viable.

Possible ways to deal with these costs would be to build a large number of rockets (economies of scale), or employ reusable rockets, In Situ Resource Utilisation or space elevators.

Architecture

A space station is a complex system with many interrelated subsystems:

1. Structure
2. Electrical power
3. Thermal control
4. Attitude determination and control
5. Orbital navigation and propulsion
6. Automation and robotics
7. Computing and communications
8. Environmental and life support
9. Crew facilities
10. Crew and cargo transportation

Past and present space stations

(dates refer to periods when stations were inhabited by crews)

• Salyut space stations (USSR, 1971-1986)
  • Salyut 1 (1971, 1 crew and 1 failed docking)
  • DOS-2 (1972, launch failure)
  • Salyut 2/Almaz (1973, failed shortly after launch)
  • Cosmos 557 (1973, re-entered eleven days after launch)
  • Salyut 3/Almaz (1974, 1 crew and 1 failed docking)
  • Salyut 4 (1975, 2 crews and 1 planned crew failed to achieve orbit)
  • Salyut 5/Almaz (1976-1977, 2 crews and 1 failed docking)
  • Salyut 6 (1977-1981, 16 crews (5 long duration, 11 short duration and 1 failed docking)
  • Salyut 7 (1982-1986, 10 crews (6 long duration, 4 short duration and 1 failed docking)

• Skylab (USA, 1973-1974, 3 crews)

• Mir (USSR/Russia, 1986-2000, 28 long duration crews)

• International Space Station (ISS) (USA, Russia, Japan, European Space Agency, Canada, Italy 2000-ongoing, 20 long duration crews to date)

Following the controlled deorbiting of Mir in 2001, the International Space Station is the only one of these currently in orbit; it has been continuously occupied since October 30, 2000.

List of occupied space stations, with statistics

Space station	Image	Launched	Reentered	Days in use		Total crew and visitors	Visits		Mass (kg)
				In orbit	Occupied		Manned	Unmanned
Salyut 1		19 April 1971 01:40:00 UTC	11 October 1971	175	24	3	2	0	18,425 kg (40,620 lb)
DOS-2		29 July 1972 Failed to enter earth orbit	29 July 1972	0	0	0	0	0	18,425 kg (40,620 lb)
Salyut 2		4 April 1973	28 May 1973	54	0	0	0	0	18,425 kg (40,620 lb)[dubious – discuss]
Cosmos 557		11 May 1973	22 May 1973	11	0	0	0	0	18,425 kg (40,620 lb)[dubious – discuss]
Skylab		14 May 1973 17:30:00 UTC	11 July 1979 16:37:00 UTC	2,249	171	9	3	0	77,088 kg (169,950 lb)
Salyut 3		25 June 1974 22:38:00 UTC	24 January 1975	213	15	2	1	0	18,500 kg (40,786 lb)[dubious – discuss]
Salyut 4		26 December 1974 04:15:00 UTC	3 February 1977	770	92	4	2	1	18,500 kg (40,786 lb)[dubious – discuss]
Salyut 5		22 June 1976 18:04:00 UTC	8 August 1977	412	67	4	2	0	19,000 kg (41,888 lb)[dubious – discuss]
Salyut 6		29 September 1977 06:50:00 UTC	29 July 1982	1,764	683	33	16	14	19,000 kg (41,888 lb)
Salyut 7		19 April 1982 19:45:00 UTC	7 February 1991	3,216	816	26	12	15	19,000 kg (41,888 lb)
Mir		19 February 1986 21:28:23 UTC	23 March 2001 05:50:00 UTC	5,511	4,594	137	39	68	124,340 kg (274,123 lb)
ISS		20 November 1998	Currently in orbit	3,883	3,209	216	47	37	286,876 kg (632,453 lb)

Crew and visitors counting is non-distinct.

• ISS statistics as of 29 May 2009

Canceled space stations

Gemini B reentry module separates from the MOL. 1967 conceptual drawing using Gemini reentry spacecraft. (USAF)

Space Station Freedom Concept (1984)

• A second Skylab unit (Skylab B) was manufactured, as a backup article; due to the high costs of providing launch vehicles, and a desire by NASA to cease Saturn and Apollo operations in time to prepare for the Space Shuttle coming into service, it was never flown. The hull can now be seen in the National Air and Space Museum, in Washington DC, where it is a popular tourist attraction.

• A number of additional Salyuts were produced, as backups or as flight articles that were later canceled.

• The U.S. Space Station Freedom program, which - despite being under development for ten years - was never launched, evolved into the International Space Station

• The Soviet/Russian Mir-2 station, which was never constructed, had some of its elements incorporated into the International Space Station.

• The Industrial Space Facility was a station proposed in the 1980s that was to be privately funded. The project was canceled when the company created to build it, Space Industries Incorporated, was unable to secure funding from the United States government.^[2]

• United States Air Force Manned Orbiting Laboratory project, canceled in 1969 about a year before the first planned test flight; this was unusual in being an explicitly military project, as opposed to the Soviet Almaz program, which was heavily intertwined with - and concealed by - the contemporaneous Salyut program.

• The European Columbus project planned to create a small space station serviced by the Hermes shuttle. It evolved into the ISS Columbus module.

Future developments

• Currently, Bigelow Aerospace is developing commercial inflatable habitat modules, derived from the earlier NASA Transhab concept, intended to be used for space station construction and for a space prize they are funding and operating, America's Space Prize. Genesis I and Genesis II are ⅓-scale unmanned prototype modules orbited to test the feasibility of inflatable structures and other systems in space. Future modules include the Galaxy, Sundancer and BA 330, each being progressively larger and more complicated, with the BA 330 intended as the full-scale manned production model for Bigelow's expandable space habitation module program.

• Project 921-2 is the working name given by the People's Republic of China for plans to create a manned space station by 2012.

• In April 2008, the Russian space agency has proposed the construction of an orbital construction yard for spacecraft too heavy to launch from Earth directly. It would not begin construction or be finished until after the decommissioning of the International Space Station.^[3] This plan was described to ISS partners by Anatoly Perminov June 17, 2009.^[4]

• Galactic Suite is a space hotel planned to be operational by 2012.

• Excalibur Almaz plans to refit Soviet Almaz space stations for commercial purposes.^[5]

See also

	Human spaceflight portal
	Spaceflight portal
	Space portal

• Kerim Kerimov, lead architect behind earliest space stations
• Lunar outpost
• Lunar space elevator
• Rotating wheel space station
• Space colonization
• Space stations and habitats in popular culture
• Space habitat

References

1. ^ Russian Space Stations (wikisource)
2. ^ Kaplan, David (August 25, 2007). "Space station idea was far-out at the time". Houston Chronicle. http://www.chron.com/disp/story.mpl/business/5083015.html. Retrieved 2007-08-26. 
3. ^ Прогресс: Россия построит на орбите завод по сборке межпланетных кораблей, Lenta.Ru, April 12, 2008. Accessed on April 13, 2008.
4. ^ Doug Messier. "Roskosmos Administrator Perminov Speaks About Past, Present and Future ISS Cooperation". http://www.parabolicarc.com/2009/06/29/roskosmos-administrator-perminov-speaks-present-future-iss-cooperation/. 
5. ^ http://www.spaceflightnow.com/news/n0908/18almaz/

Bibliography

• Neri Vela, Rodolfo (1990). Manned space stations. Their construction, operation and potential application. Paris: European Space Agency SP-1137. ISBN 9290921242. 

External links

• Where is the Space Station right now?
• Read Congressional Research Service (CRS) Reports regarding Space Stations
• Space Station Newsgroup - sci.space.station
• Space
• List of Science Fiction Space Stations
• space stations informations

v • d • e Space stations and habitats Active International Space Station (ISS) · Genesis I1 and II1 (private, Bigelow Aerospace) Human spaceflight portal Defunct Soviet Union and Russia Salyut (Salyut 1 · DOS-22 · Salyut 21, 3 · Cosmos 5571 · Salyut 33 · Salyut 4 · Salyut 53 · Salyut 6 · Salyut 7) · Polyus2 · Mir United States Skylab Cancelled Manned Orbital Laboratory · Skylab B · Galaxy ISS-incorporated Space Station Freedom · Columbus · Mir-2 Developmental People's Republic of China Project 921-2 (Tiangong 1 · Tiangong 2 · Tiangong 3) Bigelow Aerospace Sundancer · BA 330 Excalibur Almaz Almaz commercial Russia OPSEK Proposed Rotating wheel · Bernal sphere · O'Neill cylinder · Stanford torus · Wet workshop · Space habitat · Industrial Space Facility 1 Never inhabited 2 Failed launch 3 Part of the Almaz military program

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