Space station – Wikipedia, the free encyclopedia

A space station (or orbital station) is a spacecraft capable of supporting a crew, which is designed to remain in space (most commonly in low Earth orbit) for an extended period of time and for other spacecraft to dock. A space station is distinguished from other spacecraft used for human spaceflight by lack of major propulsion or landing systems. Instead, other vehicles transport people and cargo to and from the station. As of November 2012[update] two space stations are in orbit: the International Space Station, which is permanently manned, and China's Tiangong 1 (which successfully launched on September 29, 2011, after its launch was delayed from August), which is unmanned most of the time.[1][2] Previous stations include the Almaz and Salyut series, Skylab and most recently Mir.

Today's space stations are research platforms, 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. All space stations to date have been designed with the intention of rotating multiple crews, with each crew member staying aboard the station for weeks or months, but rarely more than a year. 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 2013[update], three astronauts have completed single missions of over a year, all aboard Mir.

Space stations have also 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.[3]

Space stations have been envisaged since at least as early as 1869 when Edward Everett Hale wrote "The Brick Moon".[4] The first to give serious consideration to space stations were Konstantin Tsiolkovsky in the early 20th century and Hermann Oberth about two decades later.[4] In 1929 Herman Potonik's The Problem of Space Travel was published, the first to envision a "rotating wheel" space station to create artificial gravity.

During the Second World War, German scientists researched the theoretical concept of an orbital weapon based on a space station. Pursuing Oberth's idea of a space-based weapon, the so-called "sun gun" was a concept of a space station orbiting Earth at a height of 5,100 miles (8,200km), with a weapon that was to utilize the sun's energy.[5]

In 1951, in Collier's weekly, Wernher von Braun published his design for a wheel-shaped space station, which referenced the "rotating wheel" idea first proclaimed Potonik however these concepts would never leave the concept stage during the 20th century.[4]

During the same time as von Braun pursued Potonik's ideas, the Soviet design bureaus chiefly Vladimir Chelomey's OKB-52 were pursuing Tsiolkovsky's ideas for space stations. The work by OKB-52 would lead to the Almaz programme and (together with OKB-1) to the first space station: Salyut 1. The developed hardware laid the ground for the Salyut and Mir space stations, and is even today a considerable part of the ISS space station.

The first space station was Salyut 1, which was launched by the Soviet Union on April 19, 1971. Like all the early space stations, it was "monolithic", intended to be constructed and launched in one piece, and then manned by a crew later. As such, monolithic stations generally contained all their supplies and experimental equipment when launched, and were considered "expended", and then abandoned, when these were used up.

The earlier Soviet stations were all designated "Salyut", but among these there were two distinct types: civilian and military. The military stations, Salyut 2, Salyut 3, and Salyut 5, were also known as Almaz stations.

The civilian stations Salyut 6 and Salyut 7 were built with two docking ports, which allowed a second crew to visit, bringing a new spacecraft with them; the Soyuz ferry could spend 90 days in space, after which point it needed to be replaced by a fresh Soyuz spacecraft.[6] 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.

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Space station - Wikipedia, the free encyclopedia