International Space Station
The International Space Station (ISS) is a modular space station assembled in low Earth orbit beginning in 1998 by the United States, Russia, Europe, Japan and Canada. It orbits at roughly 400 km altitude and 28,000 km/h, circling Earth about every 90 minutes — 16 sunrises and sunsets a day. Continuous occupation began on 2 November 2000; more than 280 people from 26 countries have visited since. The station supports research in biology, physics, materials science and human health, and serves as a testbed for technologies needed for deep-space exploration.