"The International Space Station (ISS) program began in 1993, with Russia joining the United States, Europe, Japan, and Canada. Crews have occupied ISS on a 4-6 month rotating basis since November 2000. The U.S. Space Shuttle, which first flew in April 1981, has been the major vehicle taking crews and cargo back and forth to ISS, but the shuttle system has encountered difficulties since the 'Columbia' disaster in 2003. Russian Soyuz spacecraft are also used to take crews to and from ISS, and Russian Progress spacecraft deliver cargo, but cannot return anything to Earth, since they are not designed to survive reentry into the Earth's atmosphere. A Soyuz is always attached to the station as a lifeboat in case of an emergency. President Bush, prompted in part by the 'Columbia' tragedy, made a major space policy address on January 14, 2004, directing NASA to focus its activities on returning humans to the Moon and someday sending them to Mars. Included in this 'Vision for Space Exploration' is a plan to retire the space shuttle in 2010. The President said the United States would fulfill its commitments to its space station partners, and the shuttle 'Discovery' made the first post-'Columbia' flight to the ISS in July 2006. Shuttle flights have continued and completion of the space station is scheduled before the shuttle is retired in 2010. Meanwhile NASA has begun development of a new crew launch vehicle, named Ares, and a crew exploration vehicle, named Orion."
CRS Report for Congress, RL33568
Federation of American Scientists: http://www.fas.org/