The International Space Station (ISS) is a research facility which is being assembled in Low Earth Orbit. Construction of the station began in 1998, and is scheduled to be complete by 2011.
Operations will continue until 2015. At present, the ISS is the largest artificial satellite in Earth orbit. It is bigger than any previous space station. The ISS program is a joint effort by the space agencies of the United States (NASA), Russia, Japan, Canada and ten European nations through the European Space Agency.
As the space station is in a Low Earth Orbit, it is visible to the naked eye. It orbits at an altitude of approximately 350 km above the surface of the Earth, clocking an average speed of 27,700 kilometers (17,210 mi) per hour and completing 15.7 orbits per day.
The first resident crew, Expedition 1, entered the station on 2 November 2000. Since then, it has been continuously staffed. So there has been a permanent human presence in space for the last nine years. At present, the station has the capacity for a crew of three.
It will be staffed by a resident crew of six starting with Expedition 20. The present crew is Expedition 18. The station has played host to astronauts from 16 different nations, and it was the destination of the first six space tourists.
The International Space Station is mainly a research laboratory. The station has an advantage over spacecraft like NASA’s Space Shuttle. As it is a long-term platform in the space environment, it allows long-duration studies to be performed. Science experiments are conducted daily across many fields, including human research, life sciences, physical sciences, and Earth observation, as well as education and technology demonstrations.
One research effort is to improve the understanding of long-term space exposure on the human body. The effect of near- weightlessness on non-human subjects is also being studied. Other research areas include the effect of the low gravity