what is the iss

The International Space Station (ISS) is a large modular space station in low Earth orbit, and it is the largest single structure humans have ever put into space. The project involves five space agencies: NASA, Roscosmos, JAXA, ESA, and CSA. The ISS serves as a microgravity and space environment research laboratory in which scientific research is conducted in astrobiology, astronomy, meteorology, physics, and other fields. It is also suited for testing spacecraft systems and equipment required for possible future long-duration missions to the Moon and Mars. The ISS is made of parts that were assembled in space by astronauts. It orbits Earth at an average altitude of approximately 250 miles and travels at 17,500 mph, which means it orbits Earth every 90 minutes. The ISS has the volume of a five-bedroom house or two Boeing 747 jetliners and is able to support a crew of six people, plus visitors. The space station is not owned by one single nation and is a "co-operative programme" between Europe, the United States, Russia, Canada, and Japan. The ISS costs about $3 billion per year for NASA to operate, roughly a third of the human spaceflight budget.