(QHA) - The International Space Station will continue operations for an additional four years, or until 2024, U.S. space agency NASA has announced, RFE/RL reports. 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.