The $100 billion orbiting station has been operational for 15 years and had been expected to operate until 2020.
More than a dozen countries participate in the orbiting laboratory, which is the length of a football field at more than 100 meters.
The space station is maintained by a rotating crew of six astronauts and cosmonauts from the United States, Russia, Europe, Canada and Japan.
Russian Soyuz rockets ferry three-man crews to and from the station.
However, U.S. companies SpaceX and Orbital Sciences are sending supplies using unmanned rockets.