The International Space Station (ISS) is a modular space station in low Earth orbit. It’s a multinational collaborative project involving five participating space agencies: NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada).
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 ISS is suited for testing spacecraft systems and equipment required for long-duration missions to the Moon and Mars.
The ISS maintains an orbit with an average altitude of 400 kilometers (250 mi) by means of reboost maneuvers using the engines of the Zvezda Service Module or visiting spacecraft. It circles the Earth in roughly 93 minutes, completing 15.5 orbits per day.
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 first ISS component was launched in 1998, and the first long-term residents arrived on 2 November 2000. The station has since been continuously occupied for 23 years and 27 days.
