The ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations and the American Skylab. The ISS programme evolved from the Space Station Freedom, an American proposal which was conceived in 1984 to construct a permanently manned Earth-orbiting station, and the contemporaneous Soviet/Russian Mir-2 proposal from 1976 with similar aims. The ISS is suited for testing the spacecraft systems and equipment required for possible future long-duration missions to the Moon and Mars. The station serves as a microgravity and space environment research laboratory in which scientific research is conducted in astrobiology, astronomy, meteorology, physics, and other fields. The ownership and use of the space station is established by intergovernmental treaties and agreements. It is a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The International Space Station ( ISS) is a modular space station (habitable artificial satellite) in low Earth orbit.