ISS

The International Space Station (ISS) is a space station, or a habitable artificial satellite, in low Earth orbit. It is a modular structure whose first component was launched in 1998. Now the largest artificial body in orbit, it can often be seen with the naked eye from Earth. The ISS consists of pressurised modules, external trusses, solar arrays and other components. ISS components have been launched by American Space Shuttles as well as Russian Proton and Soyuz rockets. The ISS serves as a microgravity and space environment research laboratory in which crew members conduct experiments in biology, human biology, physics, astronomy, meteorology and other fields. The station is suited for the testing of spacecraft systems and equipment required for missions to the Moon and Mars. The ISS maintains an orbit with an altitude of between by means of reboost manoeuvres using the engines of the Zvezda module or visiting spacecraft. It completes orbits per day. ISS is the ninth space station to be inhabited by crews, following the Soviet and later Russian Salyut, Almaz, and Mir stations as well as Skylab from the US. The station has been continuously occupied for since the arrival of Expedition 1 on 2 November 2000. This is the longest continuous human presence in space, having surpassed the previous record of held by Mir. The station is serviced by a variety of visiting spacecraft: Soyuz, Progress, the Automated Transfer Vehicle, the H-II Transfer Vehicle, Dragon, and Cygnus. It has been visited by astronauts and cosmonauts from 15 different nations. After the US Space Shuttle program ended in 2011, Soyuz rockets became the only provider of transport for astronauts at the International Space Station, and Dragon became the only provider of bulk cargo-return-to-Earth services (downmass capability of Soyuz capsules is very limited). The ISS programme is a joint project among five participating space agencies: NASA, Roscosmos, JAXA, ESA, and CSA. The ownership and use of the space station is established by intergovernmental treaties and agreements. The station is divided into two sections, the Russian Orbital Segment (ROS) and the United States Orbital Segment (USOS), which is shared by many nations. , the American portion of ISS was funded until 2024. Roskosmos has endorsed the continued operation of ISS through 2024, but have proposed using elements of the Russian Orbital Segment to construct a new Russian space station called OPSEK.