Space stations

A space station, also known as an orbital station or an orbital space station, is a spacecraft capable of supporting crewmembers, which is designed to remain in space (most commonly as an artificial satellite 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 September 2016^[update] three space stations are in orbit: the International Space Station, which is permanently manned, China's Tiangong-1 (defunct) and Tiangong-2 (launched 15 September 2016, not permanently manned). 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. Each crew member stays 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 2016^[update], four cosmonauts have completed single missions of over a year, all aboard Mir.

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