The International Space Station (ISS) is an internationally developed research facility, which is being assembled in low Earth orbit. On-orbit construction of the station began in 1998 and is scheduled for completion by 2011. The station will remain in operation until at least 2015. With a greater mass than that of any previous space station, the ISS can be seen from the Earth with the naked eye, and, as of 2010, is the largest artificial satellite orbiting the Earth. The ISS serves as a research laboratory that has a microgravity environment in which crews conduct experiments in biology, human biology, physics, astronomy and meteorology. The station has a unique environment for the testing of the spacecraft systems that will be required for missions to the Moon and Mars. The ISS is operated by Expedition crews, and has been continuously staffed since 2 November 2000—an uninterrupted human presence in space for the past 23 years and 340 days. As of January 2010, the crew of Expedition 22 is aboard. (more...)