International Space Station Russian space station called OPSEK. The 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 low Earth orbit, having surpassed the previous record of held by "Mir". It has been visited by astronauts, cosmonauts and space tourists from 17 different nations. After the American Space Shuttle programme ended in 2011, Soyuz rockets became the only
Low Earth orbit Low Earth orbit A low Earth orbit (LEO) is defined by Space-Track.org as an Earth-centered orbit with at least 11.25 periods per day (an orbital period of 128 minutes or less) and an eccentricity less than 0.25. Most of the manmade objects in space are in LEO orbits. A histogram of the mean motion of the cataloged objects shows that the number of objects drops significantly beyond 11.25. There is a large variety of other sources that define LEO in terms of altitude. The altitude of an object in an elliptic orbit can vary significantly along the orbit. Even for