International Space Station program with on-orbit refurbishment in mind. According to the Outer Space Treaty the United States is legally responsible for all modules it has launched. In ISS planning, NASA examined options including returning the station to Earth via shuttle missions (deemed too expensive, as the station(USOS) is not designed for disassembly and this would require at least 27 shuttle missions), natural orbital decay with random reentry similar to Skylab, boosting the station to a higher altitude (which would simply delay reentry) and a controlled targeted de-orbit to a remote ocean area. The technical feasibility of a controlled targeted deorbit into a remote
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.