<P> A space station is a manned satellite designed to remain in low Earth orbit for a long period of time . In general, space stations have the ability for other spacecraft to dock to them . As of 2017, the International Space Station is the only operational manned space station currently in orbit . Previous stations include the Salyut and Almaz series, Skylab, and, most recently, Mir and Tiangong 1 . </P> <P> Space stations are used to study the effects of long - term space flight on the human body . They also serve as a platform for extended scientific studies . All space stations 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 . As of 2018, Vladimir Titov, Musa Manarov, Sergei Avdeyev and Valeriy Polyakov have completed single missions of over a year, all aboard Mir . </P>

How many space stations are in orbit right now
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