The International Space Station (ISS) is an internationally developed research facility currently being assembled in Low Earth Orbit. On-orbit construction of the station began in 1998 and is scheduled to be complete by 2011, with operations continuing until at least 2015. As of 2009[update], the ISS is the largest artificial satellite in Earth orbit, with a mass larger than that of any previous space station.
The ISS is a joint project among the space agencies of the United States (National Aeronautics and Space Administration—NASA), Russia (Russian Federal Space Agency—RKA), Japan (Japan Aerospace Exploration Agency—JAXA), Canada (Canadian Space Agency—CSA) and ten European nations (European Space Agency—ESA).[a] The Brazilian Space Agency (AEB) participates through a separate contract with NASA. The Italian Space Agency (ASI) similarly has separate contracts for various activities not done within the framework of ESA's ISS projects (where Italy also fully participates). China has reportedly expressed interest in the project, especially if it would be able to work with the RKA, although as of 2009[update] it is not involved due to objections from the United States.
The space station can be seen from Earth with the naked eye, orbiting at an altitude of approximately 350 kilometres (220 mi) above the surface of the Earth, travelling at an average speed of 27,724 kilometres (17,227 mi) per hour, completing 15.7 orbits per day.
The ISS has been continuously staffed since the first resident crew, Expedition 1, entered the station on 2 November 2000. This has provided an uninterrupted human presence in space for the last &0000000000000008.0000008 years, &0000000000000269.000000269 days. Prior to May 2009, the station had the capacity for a crew of three. However, to fulfil an active research programme, since the arrival of Expedition 20, it has been staffed by a resident crew of six. The crew of Expedition 20 is currently aboard.
Early crew members all came from the American and Russian space programmes until German ESA astronaut Thomas Reiter joined the Expedition 13 crew in July 2006. The station has been visited by astronauts from 16 different nations, and it was the destination of the first six space tourists.