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Space Station A space station is an artificial structure designed for humans to live in outer space. 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. 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 of 437.7 days was set by Valeri Polyakov aboard Mir from 1994 to 1995. As of 2005, 3 astronauts have completed single missions of over a year, all aboard Mir.
Past and present space stations
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 manned since October 30, 2000. 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 & 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 also produced, as backups or as flight articles which were later cancelled. The International Space Station evolved from the American Space Station Freedom program, which - despite being under development for ten years - was never launched; it incorporated elements of a Mir replacement station ("Mir 2") which was also never constructed. Other cancelled space station programs included the United States Air Force Manned Orbiting Laboratory project, cancelled 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. Currently, Bigelow Aerospace is commercially developing inflatable habitat modules, derived from the earlier Transhab concept, intended to be used for space station construction and for a space prize they are funding and operating, America's Space Prize. Types of space stationBroadly 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 7, a change was seen; these were built with two docking ports, which allowed a second crew to visit, bringing a new spacecraft (for technical reasons, a Soyuz capsule cannot spend more than a few months on orbit, even powered down, safely) with them. This allowed for a crew to man the station continually. The presence of a second port also 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. 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 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. These stations have various issues that limit their long-term habitability, such as very low recycling rates, 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, most current habitats even have an acute danger of radiation poisoning. Some space habitats 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, because even for a small station, the extra equipment is too expensive to place in orbit at current (2005) launch costs. List of occupied space stations, with statistics
In fictionA large amount of science fiction is set on space stations. A notable example is Babylon 5, a series set on a space station by that name far into the future. Similarly, Deep Space 9 is a prominent space station in the Star Trek story line. It was built by the Cardassians around Bajor and later staffed by Federation personnel. The film (and novel) 2001: A Space Odyssey contains a large space station, built as a revolving ring; this has proven to be one of the iconic images of a space station in popular culture. The James Bond film Moonraker featured a space station which serves as Hugo Drax's lair and a base to nerve-gas Earth. The Star Wars films A New Hope (Star Wars) and Return of the Jedi each feature a heavily armored space station known as the Death Star, which is capable of destroying a planet. Some may dispute the usage of the term space station to describe the Death Stars because they are capable of traveling great distances. External linksSalyut Space StationThe Salyut (Russian: Салют, Salute or Firework) program was a series of space stations launched by the Soviet Union in the 1970s. The Salyuts were all relatively simple structures consisting of a single main module placed into orbit in a single launch. The program was originally designated the DOS 7-K program, with each Salyut station receiving a designation. 
Salyut 1 (DOS 1) was launched April 19, 1971. It was the first space station ever orbited. Its first crew launched in Soyuz 10 but was unable to board it due to a failure in the docking mechanism; its second crew launched in Soyuz 11 and remained on board for 23 productive days. Unfortunately, a pressure-equalization valve in the Soyuz 11 reentry capsule opened prematurely when the crew returned to Earth, killing all three. Salyut 1 reentered Earth's atmosphere October 11, 1971. Salyut 2 was launched April 3, 1973. It was not really a part of the same program as the other Salyut stations, instead being the highly classified prototype military space station Almaz. It was given the designation Salyut 2 to conceal its true nature. Despite its successful launch, within two days the as-yet-unmanned Salyut 2 began losing pressure and its flight control failed; the cause of the failure was likely due to shrapnel piercing the station when the discarded Proton rocket upper stage that had placed it in orbit later exploded nearby. The Salyut space station that Almaz had substituted for, designated DOS 3, was launched on May 11, 1973, three days before the launch of Skylab. Due to errors in the flight control system while out of the range of ground control, the station fired its orbit-correction engines until it consumed all of its fuel. Since the spacecraft was already in orbit and had been registered by Western radar, the Soviets disguised the launch as "Cosmos 557" and quietly allowed it to reenter Earth's atmosphere and burn up a week later. It was revealed to have been a Salyut station only much later. Salyut 3 was launched on June 25, 1974. It was another Almaz military space station, this one launched successfully. It tested a wide variety of reconnaissance sensors, returning a canister of film for analysis. On January 24, 1975 trials of the on-board 23mm Nudelmann aircraft cannon (other sources say it was a Nudelmann NR-30 30mm gun) were conducted with positive results at ranges from 3000 m to 500 m. Cosmonauts have confirmed that a target satellite was destroyed in the test. The next day, the station was ordered to deorbit. Only one of the three intended crews successfully boarded and manned the station, brought by Soyuz 14; Soyuz 15 attempted to bring a second crew but failed to dock. Nevertheless, Salyut 3 was an overall success. Salyut 4 (DOS 4) was launched on December 26, 1974. It was essentially a copy of the DOS 3, and unlike its ill-fated sibling it was a complete success. Three crews made stays aboard Salyut 4 (Soyuz 17, Soyuz 18 and Soyuz 21), including one of 63 days duration, and an unmanned Soyuz capsule remained docked to the station for three months, proving the systems' long-term durability. Salyut 4 was deorbited February 3, 1977. Salyut 5 was launched on June 22, 1976. It was the third and last Almaz military space station. Its launch and subsequent mission were both completed successfully, with three crews launching and two (Soyuz 21 and Soyuz 24) successfully boarding the craft for lengthy stays (the second crew on Soyuz 23 was unable to dock and had to abort). Salyut 5 reentered on August 8, 1977. Following Salyut 5 the Soviet Military decided that the tactical advantages were not worth the expense of the programme and withdrew. The focus for the later missions was propaganda. Salyut 6 was launched on September 29, 1977. Although it resembled the previous Salyut stations in overall design, it featured several revolutionary advances including a second docking port where an unmanned Progress cargo spacecraft could dock and refuel the station. From 1977 until 1982 Salyut 6 was visited by five long-duration crews and 11 short-term crews, including cosmonauts from Warsaw Pact countries. The very first long-duration crew on Salyut 6 broke a record set onboard Skylab, staying 96 days in orbit. The longest flight onboard Salyut 6 lasted 185 days. The fourth Salyut 6 expedition deployed a 10-meter radio-telescope antenna delivered by a cargo ship. After Salyut 6 manned operations were discontinued in 1981, a heavy unmanned spacecraft called TKS and developed using hardware left from the canceled Almaz program was docked to the station as a hardware test. Salyut 6 was deorbited July 29, 1982. Salyut 7 was launched on April 19, 1982. It was the back-up vehicle for Salyut 6 and very similar in equipment and capabilities, though several more advanced features were included. It was aloft for four years and two months, during which time it was visited by 10 crews constituting 6 main expeditions and 4 secondary flights (including French and Indian cosmonauts). Aside from the many experiments and observations made on Salyut 7, the station also tested the docking and use of large modules with an orbiting space station. The modules were called "Heavy Cosmos modules." They helped engineers develop technology necessary to build Mir. Salyut 7 deorbited on February 7, 1991. List of Soviet / Russian space stations
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Skylab Space Station
Skylab was the first space station the United States launched into orbit. The 75 metric ton station was in Earth orbit from 1973 to 1979, and visited by crews three times in 1973 and 1974.
History
Skylab was launched May 14, 1973 by a two-stage version of the Saturn V booster (the SL-1 mission). Severe damage was sustained during launch, including the loss of the station's micrometeoroid shield/sun shade and one of its main solar panels. Debris from the lost micrometeoroid shield further complicated matters by pinning the remaining solar panel to the side of the station, preventing its deployment and thus leaving the station with a huge power deficit. The station underwent extensive repair during a spacewalk by the first crew, which launched on May 25, 1973 (the SL-2 mission) atop a Saturn IB. Two additional missions followed on July 28, 1973 (SL-3) and November 16, 1973 (SL-4) with stay times of 28, 59, and 84 days, respectively. The last Skylab crew returned to Earth on February 8, 1974. 
Mission of SkylabSkylab was actually the refitted S-IVB second stage of a Saturn IB booster (from the AS-212 vehicle), a leftover from the Apollo program originally intended for one of the canceled Apollo earth orbital missions. A product of the Apollo Applications Program (a program tasked with finding long-term uses for Apollo program hardware), Skylab was originally planned as a minimally-altered S-IVB to be launched on a Saturn IB. The small size of the IB would have required Skylab to double as a rocket stage during launch, only being retrofitted as a space station once on-orbit. With the cancellation of Apollo missions 18-20 a Saturn V was made available and thus the "Wet Workshop" concept, as it was called, was put aside and Skylab was launched dry and fully outfitted. Skylab's grid flooring system was a highly visible legacy of the wet workshop concept. The mission computer used aboard Skylab was the IBM System/4Pi TC-1, a relative of the AP-101 Space Shuttle computers. Operations on Skylab
All told, Skylab orbited Earth 2,476 times during the 171 days and 13 hours of its occupation during the three manned Skylab missions. Astronauts performed ten spacewalks totalling 42 hours 16 minutes. Skylab logged about 2,000 hours of scientific and medical experiments, including eight solar experiments. The coronal holes in the Sun were discovered thanks to these efforts. Many of the experiments conducted investigated the astronauts' adaptation to extended periods of microgravity. Each Skylab mission set a record for the duration of time astronauts spent in space. End of SkylabFollowing the last mission, Skylab was left in a parking orbit expected to last at least 8 years. The Space Shuttle was planned to dock with and elevate Skylab to a higher safe altitude in 1979, however the shuttles were not able to launch until 1981. A planned unmanned satellite called the Teleoperator was to be launched to save Skylab, but funding never materialised. Skylab was considered junk by many. It was falling apart, according to the visiting astronauts. It had suffered great damage during launch when the solar panel tore off with the solar shield. It needed new gyroscopes, fuels, equipment, life support systems, plumbing, and much more. Increased solar activity, heating the outer layers of the earth's atmosphere and thereby increasing drag on Skylab, led to an early reentry at approximately 16:37 UTC July 11, 1979. Earth reentry footprint was a narrow band (approx. 4° wide) beginning at about 48° S 87° E and ending at about 12° S 144° E, an area covering portions of the Indian Ocean and Western Australia. Debris was found between Esperance, Western Australia, and Rawlinna, Western Australia, 31–34°S, 122–126°E. As this area was sparsely populated, there were no casualties. Skylab's demise was an international media event, with merchandising, wagering on time and place of re-entry and nightly news reports. The San Francisco Examiner offered a $10,000 prize for the first piece of Skylab to be delivered to their offices. An Australian farmer claimed the bounty. In a coincidence for the organisers, the annual Miss Universe pageant was scheduled to be held a few days later, on July 20, 1979, in nearby Perth, Western Australia. A large piece of Skylab debris was displayed on the stage. Three flight-quality Skylabs were built. The first one was that which crashed in Western Australia; the second, a backup, is on display at the National Air and Space Museum in Washington, DC and the third is kept at the Lyndon B. Johnson Space Center in Houston, Texas. Skylab Expeditions
See also
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Mir Space Station
Mir (Мир, which can mean both world and peace in Russian) was a highly successful Soviet (and later Russian) space station. It was humanity's first consistently inhabited long-term research station in space. Through a number of collaborations, it was made internationally accessible to cosmonauts and astronauts of many different countries. Mir was assembled in orbit by successively connecting several modules, each launched separately from February 19, 1986 to 1996. The station existed until March 23, 2001, at which point it was deliberately de-orbited and broke apart during atmospheric re-entry.
History
Mir was based upon the Salyut series of space stations previously launched by the Soviet Union (seven Salyut space stations had been launched since 1971). It was mainly serviced by Russian-manned Soyuz spacecraft and Progress cargo ships, but it was anticipated that it would also be the destination for flights by the later abandoned Buran space shuttle. The orbiting Mir's purpose was to provide a large and livable scientific laboratory in outer space. The United States had planned to build Space Station Freedom as its counterpart to Mir, but this project was cancelled after the fall of the Soviet Union made an international cooperation possible (see International Space Station). Also, the space shuttle Challenger exploded less than a month before Mir was launched into orbit (see Space Shuttle Challenger disaster). In later years, after the end of the Cold War, the Shuttle-Mir program combined Russia's Mir capabilities with United States space shuttles and allowed a couple of American and other western astronauts to visit or stay long-term on the station. The visiting US shuttles used a modified docking collar originally designed for the Soviet Buran shuttle, mounted on a bracket originally designed for use with Space Station Freedom. With the space shuttle docked to Mir the temporary enlargements of living and working areas amounted to a complex that was the world's largest spacecraft at that time in space history, with a combined mass of 250 tons. Inside, the 100-ton Mir looked like a cramped labyrinth, crowded with hoses, cables and scientific instruments – as well as articles of everyday life, such as photos, children's drawings, books and a guitar. It commonly housed three crewmembers, but it sometimes supported as many as six for up to a month. Except for two short periods, Mir was continuously occupied until August 1999. The journey of the 15-year-old Russian space station ended March 23, 2001, as Mir re-entered the Earth's atmosphere near Nadi, Fiji, and fell into the South Pacific Ocean. Near the end of its life, there were plans for private interests to purchase Mir, possibly for use as the first orbital television/movie studio, but the station was deemed too unstable to be safely used any further. Many in the space community still felt that at least some of Mir was salvageable and that considering the extremely high costs of getting material into orbit, simply disposing of Mir was a seriously wasted opportunity. In addition to Soviet/Russian cosmonauts, Mir hosted international scientists and U.S. astronauts. Mir modulesThe Mir space station was constructed by connecting several Mir modules, each launched into orbit separately by the Proton rocket, except for the Docking Module, which was brought to Mir by the Space Shuttle.
Core ModuleThe Core Module provided living quarters and station control. It was equipped with six docking ports, and it served as a core of the multi-modular space station. It was launched on February 19, 1986 at 21:28 UTC from Baikonur LC200 with a Proton 8K82K. Its initial orbit had a Perigee of 387 km and Apogee of 395 km. The inclination was 51.6 deg for the duration of the station (and is the same for the International Space Station). The initial period was 92.4 min. Although the Core Module resembled Salyut 6 and Salyut 7, there was also major differences between them. Because most of the additional instruments can be placed onboard "add-on" modules, much of the scientific equipment found on Salyut space stations were absent. It is equipped with six docking ports, and it served as a core of the later multi-modular space station. Kvant-1Kvant-1 (means "quantum") was originally planned to dock with Salyut 7 , Mir's predecessor. The module experienced technical problems during module development, however, and it was reassigned for Mir. The module carried the first set of six gyroscopes for altitude control. The module also carried instruments for X-ray and ultraviolet astrophysical observation. The initial rendezvous of the Kvant-1 module with Mir on April 5 was troubled with the failure of the onboard control system. After the failure of the second attempt to dock, the onboard cosmonauts conducted a spacewalk to fix the problem. They found a trash bag between the module and the station, which prevented the docking. The bag somehow made its way into the cargo before launch. They removed the bag and completed docking on April 12. Kvant-2The Kvant-2 module was based on a TKS transport spacecraft. It contained scientific instruments and the crew's shower. It also contained a second set of gyroscopes that was mounted on the exterior of the spacecraft, and a new life support system. KristallKristall was a technology, material processing, geophysics and astrophysics laboratory. SpektrSpektr served as the living and working space for American astronauts. The module moved positions on the station on July 17, 1995 to its final position by the robotic arm aboard the station. Docking ModuleThe Docking Module provided a safe and stable port for the Space Shuttle. PrirodaPriroda conducted Earth remote sensing. Before, during and after the Shuttle-Mir Program, Mir was tended and resupplied by manned Soyuz capsules and unmanned Progress cargo vehicles. Names
In Russian, Mir (Мир) means "peace," and connotes "community." Kvant (Квант) means "quantum," a name derived from its purpose to provide research in astrophysics by measuring electromagnetic spectra and x-ray emissions. Kristall (Кристалл) means "crystal," and a main purpose of this module is to develop biological and materials production technologies in the space environment. Spektr (Спектр) means "spectrum," so named for its atmospheric sensors. Priroda (Природа) means "nature." Progress (Прогресс) means the same as it does in English. Soyuz (Союз) means "union," so named for the USSR (Sovietskii Soyuz, Советский Союз = Soviet Union) and because the spacecraft was a union of three smaller modules. Before the Russian Revolution a "mir" was a piece of land worked by a community of peasants. There was very strong social pressure against peasants leaving the land, because taxes were levied on the mir as a whole. If some peasants left, the remaining peasants would have to pay more per person. International cooperation
In September 1993 U.S. Vice-president Al Gore and Russian prime minister Viktor Chernomyrdin announced plans for a new space station, which would later be called the International Space Station, or ISS. They also agreed that, in preparation for this new project, the U.S. would be largely involved in the Mir project in the years ahead, under the code name Phase One (the ISS being Phase Two). Space shuttles would take part in the transportation of supplies and people to and from the Mir. U.S. astronauts would live in the Mir for many months on end. Thus the U.S. could share and learn from the unique experience that Russia has with long duration space trips. 
Starting March 1995 seven U.S. astronauts consecutively spent 28 months on the Mir. During their stay the space station went through rough times and several acute emergencies occurred, notably a large fire on February 23, 1997, and a collision with a Progress (unmanned) cargo ship on June 25, 1997. In both occasions complete evacuation of the Mir (there was a Soyuz escape craft for return to earth) was avoided with a narrow margin. The second disaster left a hole in the Spektr module, which then was sealed off from the rest of the station. Several space walks were needed to restore full power to the Mir (ironically, one of the 'space walks' was inside the Spektr module from which all the air had escaped). The cooperation between the U.S. and Russia proved far from easy. Distrust, lack of coordination, language problems, different views of each others' responsibilities and divergent interests caused many problems. After the emergencies, the U.S. Congress and NASA considered whether the U.S. should abandon the program out of concern for astronauts' safety. NASA administrator Daniel S. Goldin decided to continue the program. In June 1998, the final U.S. Mir astronaut Andy Thomas, who was actually an Australian, left the station aboard the Space Shuttle Discovery. The story of Phase One is described in great detail by Bryan Burrough in his book Dragonfly: NASA and the Crisis Aboard Mir (1998). The Mir space station was originally planned to be followed by a Mir 2, and elements of that project, including the core module (now called Zvezda) which was labeled as "Mir-2" for quite some time in the factory, are now an integral part of the International Space Station. Mir in popular culture
Expeditions, spacewalks and crews
See also
References
External linksWikimedia Commons has media related to:
International Space Station (ISS)
The International Space Station (ISS) is a joint project of five space agencies: the National Aeronautics and Space Administration (United States), the Russian Federal Space Agency (Russian Federation), the Japan Aerospace Exploration Agency (Japan), the Canadian Space Agency (Canada) and the European Space Agency (Europe)[1]. The Brazilian Space Agency (Brazil) participates through separate contract with NASA. The Italian Space Agency similary has separate contracts for various activities, that are not done in the framework of ESA ISS works (where Italy also fully participates). The space station is located in orbit around the Earth at an altitude of approximately 360 km (220 miles), a type of orbit usually termed low Earth orbit (The actual height varies over time by several kilometres due to atmospheric drag and reboosts [2]). It orbits Earth in a period of about 92 minutes; by June 2005 it had completed more than 37,500 orbits since launch of the Zarya module on November 20, 1998. In many ways the ISS represents a merger of previously planned independent space stations: Russia's Mir 2, United States' Space Station Freedom and the planned European Columbus and Japanese Experiment Module. Due to the ISS, there is a permanent human presence in space, as the ISS' crew size has been at all times at least two since the first permanent crew entered the ISS on November 2, 2000. It is serviced primarily by the Space Shuttle, Soyuz and Progress spacecraft units. The ISS is currently still under construction with a projected completion date of 2010. At present, the station has a capacity for a crew of three. So far, all permanent crewmembers have come from the Russian or United States space programs. The ISS has however been visited by astronauts from a large number of other countries and was also the destination of the first three space tourists.
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