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The International Space Station (ISS) is a permanently crewed, multinational space laboratory in low-Earth orbit. Continuously staffed since 2 November 2000, it is the longest-running space station program of all time, and consistently cited among the world's most ambitious engineering projects. Boasting a pressurized volume of 932 cubic meters, the ISS has an interior space equivalent to 24 shipping containers and with regular supply missions can indefinitely host up to 7 crewmembers.

The station is typically staffed by dual 3-person crews assigned to overlapping six-month missions, with each unique complement of 6 people composing a numbered Expedition (each 3-person crew will serve on two Expeditions during their stay). NASA and Roscosmos have also experimented with one-year crews.

NASA and its international partners conduct research aboard the ISS that helps us learn more about the effects of long-term spaceflight on the human body. They also test technologies that will be needed for human missions beyond low-Earth orbit.

The final flyaround


The final flyaround
The International Space Station is viewed from Space Shuttle Atlantis on July 19, 2011 during the shuttle program's final flyaround inspection.

See the station

The station's altitude averages just over 400 kilometers. Earth's atmosphere continually drags it down. Mission controllers reboost its altitude regularly using either engines on the Zvezda service module or on visiting spacecraft. The station’s high, 51.64-degree orbital inclination carries it over 90 percent of the world's population, and its large size and reflective solar panels make it easy to spot from even brightly lit cities. You can sign up to receive text or email alerts from NASA when the station is visible from your location.

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Science and research

Science and research aboard the ISS generally fall into 4 categories:

NASA publishes annual highlights of station research that include links to research papers for major station investigations, as well as metrics for peer-reviewed papers related to ISS science. Data from some physical science investigations can be accessed through NASA's Physical Sciences Informatics System.

The 2005 NASA Authorization Act designated the ISS as a National Laboratory, opening it up to research by other federal entities and the private sector. The station’s National Lab activities are managed by the Center for the Advancement of Science in Space, CASIS.

The ISS also offers a means of cooperation for five of the world’s major space agencies: NASA, Roscosmos, ESA, JAXA, and CSA. Station astronauts regularly videoconference with students around the world.

ISS facts

The ISS as of August 2019

NASA / Wikipedia

The ISS as of August 2019
See source file for more information.

Explore the ISS using Google Street View

Crew Vehicles

The Russian Soyuz is currently the only vehicle able to carry astronauts to the ISS, following the retirement of the space shuttles in 2011. In September 2014, NASA selected SpaceX and Boeing for space station crew transportation, the culmination of a plan to return crewed launch capability to the United States.


Soyuz TMA-15M


Soyuz TMA-15M
Soyuz TMA-15M departs the International Space Station on 11 June 2015 carrying NASA's Terry Virts, ESA's Samantha Cristoforetti, and Roscosmos' Anton Shkaplerov.

The Soyuz has been in service since 1967. Launching on the identically named Soyuz rocket, it has 3 sections: a pressurized descent module that carries up to 3 crew members during liftoff and landing, a pressurized orbital module used on orbit for storage and extra crew space, and a separate, inaccessible service module that houses the propulsion, solar arrays, and other instrumentation. The capsule is not reusable.

Crew Dragon

Crew Dragon 20 meters from ISS


Crew Dragon 20 meters from ISS
Crew Dragon holds position 20 meters away from the International Space Station's forward docking port on 3 March 2019, during its inaugural test flight.

Derived from SpaceX's Dragon cargo vehicle that debuted in X, Crew Dragon consists of a pressurized capsule capable of hosting up to 7 astronauts, and an unpressurized trunk for cargo space as well as power via a solar array-lined exterior. Crew Dragon launches on Falcon 9; the trunk is jettisoned before vehicle reentry. The capsule is designed to be reusable.

CST-100 Starliner

Boeing CST-100 Starliner


Boeing CST-100 Starliner
An artist's rendering of Boeing's Starliner spacecraft.

Starliner consists of a pressurized capsule capable of hosting up to 7 astronauts, and a service module for propulsion and power via solar panels on the bottom that provide 2,900 watts of power. Starliner launches on the Atlas V, and will eventually launch on Vulcan. It can touch down on land using airbags; the capsule is designed to be reusable. 

Crew Vehicle resources

Cargo Vehicles

Four uncrewed cargo vehicles currently service the International Space Station: the SpaceX Dragon, the Northrop Grumman Cygnus, the Russian Progress, and the Japanese H-II Transfer Vehicle (HTV). A fifth cargo spacecraft, the Sierra Nevada Dream Chaser, is expected to come online in 2021.

Major milestones

External resources


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