A space station, also known as an orbital station or an orbital space station, is a spacecraft capable of supporting a human crew in orbit for an extended period of time, and is therefore a type of space habitat. It lacks major propulsion or landing systems. Stations must have docking ports to allow other spacecraft to dock to transfer crew and supplies.
The purpose of maintaining an orbital outpost varies depending on the program. Space stations have most often been launched for scientific purposes, but military launches have also occurred. As of 2021, there is one fully operational and permanently inhabited space station in low Earth orbit: the International Space Station, which is used to study the effects of spaceflight on the human body as well as to provide a location to conduct a greater number and longer length of scientific studies than is possible on other space vehicles. China's Tiangong Space Station is under construction. Both India and Russia have proposed to build stations for the coming decades.