International Space Station program ocean was found to be possible only with Russia's assistance. At the time ISS was launched, the Russian Space Agency had experience from de-orbiting the Salyut 4, 5, 6, and 7 space stations, while NASA's first intentional controlled de-orbit of a satellite (the Compton Gamma Ray Observatory) would not occur for another two years. NASA currently has no spacecraft capable of de-orbiting the ISS at the time of decommissioning. Skylab, the only space station built and launched entirely by the US, decayed from orbit slowly over 5 years, and no attempt was made to de-orbit the station using a deorbital
International Space Station Space Shuttle to dock to the space station. At that time, the Russian station "Mir" was still inhabited. The ISS remained unmanned for two years, while "Mir" was de-orbited. On 12 July 2000, "Zvezda" was launched into orbit. Preprogrammed commands on board deployed its solar arrays and communications antenna. It then became the passive target for a rendezvous with "Zarya" and "Unity": it maintained a station-keeping orbit while the "Zarya"-"Unity" vehicle performed the rendezvous and docking via ground control and the Russian automated rendezvous and docking system. "Zarya" computer transferred control of the station to "Zvezda" computer soon after docking.