The International Space Station (ISS) is a research facility currently being assembled in space. The station is in a low Earth orbit (Box orbit) and can be seen from earth with the naked eye: its altitude varies from 319.6 km to 346.9 km above the surface of the Earth (approximately 199 miles to 215 miles). It travels at an average speed of 27,744 km (17,240 miles) per hour, completing 15.7 orbits per day. The ISS is a joint project between the space agencies of the United States (NASA), Russia (RKA), Japan (JAXA), Canada (CSA) and several European countries (ESA).
The Brazilian Space Agency (AEB, Brazil) participates through a separate contract with NASA. The Italian Space Agency similarly has separate contracts for various activities not done in the framework of ESA's ISS works (where Italy also fully participates). China has reportedly expressed interest in the project, especially if they are able to work with the RKA. They have not been invited to become involved, however.
The ISS is a continuation of what began as the U.S. Space Station Freedom, the funding for which was cut back severely. It represents a merger of Freedom with several other previously planned space stations: Russia's Mir 2, the planned European Columbus and the Japanese Experiment Module. The projected completion date is 2010, with the station remaining in operation until around 2016. As of 2007, the ISS is already larger than any previous space station.
The ISS has been continuously inhabited since the first resident crew entered the station on November 2, 2000, thereby providing a permanent human presence in space. The crew of Expedition 15 are currently aboard. The station is serviced primarily by Russian Soyuz and Progress spacecraft and by U.S. Space Shuttle orbiters. At present the station has a capacity for a crew of three. Early crewmembers all came from the Russian and U.S. space programs. German ESA astronaut Thomas Reiter joined the Expedition 13 crew in July 2006, becoming the first crewmember from another space agency. The station has, however, been visited by astronauts from 14 countries, and the Expedition 16 crew will include members from all five space agencies that form the ISS partnership. The ISS was also the destination of the first five space tourists.