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 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. Previous stations include the Almaz and Salyut series, Skylab and most recently Mir.