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Space station
The International Space Station in 2007 Space stations are currently (as of 2007) 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 2008, three astronauts have completed single missions of over a year, all aboard Mir.
UsesSpace 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 stationsMonolithicBroadly 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. ModularThe 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. Habitability issuesThese 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, because even for a small station, the extra equipment is too expensive to place in orbit at current (2008) launch costs. Possible ways to deal with these costs would be building lots of rockets (economies of scale), reusable rockets, In Situ Resource Utilisation or if space elevators are ever able to be constructed. ArchitectureA space station is a complex system with many subsystems. These subsystems are interrelated in a medium or large sense; thus, each subsystem is designed considering the others. All of these subsystems should be safe and function reliably. The main subsystems of a space station are:
Past and present space stations(dates refer to periods when stations were inhabited by crews)
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. As of 9 September, 2006, it was 44.5 metres (146 ft) in length along the core between the Destiny and Zvezda modules or 52 metres (171 ft) long when a Progress is attached, and has a mass of 183.3 metric tons (202.1 short tons). List of occupied space stations, with statistics
Crew and visitors counting is non-distinct.
Canceled space stations
Gemini B reentry module separates from the MOL. 1967 conceptual drawing using Gemini reentry spacecraft. (USAF) 
Space Station Freedom Concept (1984)
Future developments
ReferencesBibliographySee also
External links
bg:?????????? ??????? ca:Estació espacial cs:Vesmírná stanice da:Rumstation de:Raumstation es:Estación espacial eo:Kosmostacio fa:??????? ????? fr:Station spatiale fy:Romtestasjon ko:?? ??? id:Stasiun luar angkasa it:Stazione spaziale he:???? ??? ka:???????? ??????? lv:Orbit?l? stacija lt:Kosmin? stotis hu:?rállomás nl:Ruimtestation ja:???????? no:Romstasjon nn:Romstasjon pl:Stacja orbitalna pt:Estação espacial ro:Sta?ie spa?ial? ru:??????????? ??????? simple:Space station sk:Kozmická stanica sl:Vesoljska postaja sh:Svemirska stanica stq:Ruumstation fi:Avaruusasema sv:Rymdstation ta:???????? ?????????? tg:????????? ?????? tr:Uzay istasyonu zh:??? Source: Wikipedia | The above article is available under the GNU FDL. | Edit this article
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