International Space Station

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 completed by 2011, with operations continuing until at least 2015.

The station can be seen from the Earth with the naked eye, and, as of 2009, is the largest artificial satellite in Earth orbit, with a mass larger than that of any previous space station. The ISS serves as a long-term research laboratory in space, with experiments in fields including biology, human biology, physics, astronomy and meteorology being carried out daily in the station's microgravity environment.

The station also provides a safe testing location for efficient, reliable spacecraft systems that will be required for long-duration missions to the Moon and Mars. The ISS and its experiments are operated by long-duration Expedition crews, with the station being continuously staffed since the first resident crew, Expedition 1, arrived on 2 November 2000. This has provided an uninterrupted human presence in space for the last 9 years and 35 days. As of 1 December 2009, the crew of Expedition 22 is aboard.

The station represents a union of several space station projects including the American Space Station Freedom, the Soviet/Russian Mir-2, the European Columbus and the Japanese Kibo. Budget issues with each station, however, led to the separate projects being merged into a single multi-national space station.

The ISS project began in 1994 with the Shuttle-Mir programme, and the first module of the station, Zarya, was launched in 1998 by Russia. Assembly has been ongoing ever since, with a complex of pressurized modules, external trusses and other components being launched by American Space Shuttles, Russian Proton rockets and Russian Soyuz rockets.

As of November 2009, the station consists of eleven pressurised modules and an extensive Integrated Truss Structure (ITS). Power is provided by sixteen large solar arrays mounted on the external truss, in addition to four smaller arrays on Russian modules.

The station is maintained at an orbit between 278 km (173 mi) and 460 km (286 mi) altitude, and travels at an average speed of 27,724 kilometres (17,227 mi) per hour, completing 15.7 orbits per day.

The ISS is operated as a joint project between the American National Aeronautics and Space Administration (NASA), the Russian Federal Space Agency (RKA), the Japan Aerospace Exploration Agency (JAXA), the Canadian Space Agency (CSA), and the European Space Agency (ESA).

Ownership and utilization of the space station is set out via several intergovernmental treaties and agreements, with the Russian Federation retaining full ownership of its own modules, and the rest of the station being allocated between the other international partners.

The cost of the station project has been estimated by ESA as 100 billion over a course of 30 years, although cost estimates vary between 35 billion dollars and 160 billion dollars, making the ISS the most expensive object ever constructed. This large cost has meant that the ISS programme has been the target of various criticisms over its financing, research capabilities and technical design.

The various sections of the station are controlled by several mission control centres on the ground, including MCC-H, TsUP, Col-CC, ATV-CC, JEM-CC, HTV-CC and MSS-CC. The station is serviced by a wide variety of manned and unmanned spacecraft, including the Soyuz spacecraft, Progress spacecraft, Space Shuttle, Automated Transfer Vehicle, and H-II Transfer Vehicle, and has been visited by astronauts and cosmonauts from 15 different nations.


The International Space Station serves primarily as a research laboratory, offering an advantage over spacecraft such as NASA's Space Shuttle because it is a long-term platform in the space environment, allowing long-duration studies to be performed, both on specific experiments and on the human crews that operate them.

The presence of a permanent crew means that the station offers benefits over unmanned spacecraft as experiments can be monitored, replenished, repaired or replaced as required by the crew, as can other components of the spacecraft itself. Scientists on the ground have swift access to their data and can modify experiments or launch new ones as and when required; benefits generally unavailable on specialized unmanned spacecraft.

Crews flying long-term expeditions lasting several months, conduct scientific experiments each day (approximately 160 man-hours a week) across many fields, including human research (space medicine), life sciences, physical sciences and Earth observation.

As of the conclusion of Expedition 15, 138 major science investigations had been conducted on the ISS since the launch of Zarya in 1998. Scientific findings, in fields ranging from basic science to exploration research, are being published every month.

The ISS provides a testing location for efficient, reliable spacecraft systems that will be required for long-duration missions to the Moon and Mars, allowing for equipment to be evaluated in the relatively safe location of Low Earth Orbit. This provides experience in maintaining, repairing, and replacing systems on-orbit, which will be essential in operating spacecraft further from Earth. This aspect of ISS operations reduces mission risks, and advances the capabilities of interplanetary spacecraft.

Part of the crew's mission is educational outreach and international cooperation. The crews of the ISS provide educational opportunities for students back home on Earth, including student-developed experiments, educational demonstrations, student participation in classroom versions of ISS experiments, NASA investigator experiments, and ISS engineering activities. The ISS program itself, and the international cooperation that it represents, allows 14 nations to live and work together in space, providing important lessons that can be taken forward into future multi-national missions.


According to the original Memorandum of Understanding between NASA and RSA, the International Space Station is intended to be:

  • a laboratory in space
  • a permanent observatory
  • a transportation node
  • a servicing depot
  • a factory
  • a staging base for possible future missions

    International Space Station

    When completed in late 2011, the ISS will consist of sixteen pressurized modules with a combined volume of around 1,000 cubic metres (35,000 cu ft). These modules include laboratories, docking compartments, airlocks, nodes and living quarters. Fifteen of these components are already in orbit, with the remaining one awaiting launch. Each module was or will be launched either by the Space Shuttle, Proton rocket or Soyuz rocket.

    It all began with Zarya

    In the News ...

    Stunning Image: Space Shuttle Endeavour dock with ISS   NASA - June 8, 2011
    Majestic shuttle in unique station image   BBC - June 8, 2011

    The picture was taken by Italian astronaut Paolo Nespoli as he left the International Space Station in May in a Soyuz capsule to return to Earth. Safety procedures mean the Russian vehicle would never normally be in transit when a shuttle is present. It makes this the first-ever image of an American orbiter docked to the ISS. Endeavour sits firmly on the bow of the station, which is moving across the surface of the Earth at a speed of 27,000km/h (17,000mph) and at an altitude of approximately 355km (220 miles). Nespoli's camera is looking along the ISS's truss, or backbone, which carries the four sets of giant solar wings. The stern is occupied by Europe's robotic freighter - the Johannes Kepler ship.

    First Photos: Space Station's Observation Deck Unveiled   National Geographic - February 20, 2010