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 leftover USOS hardware and '"Zvezda" 2' as a refuelling depot and service station located at one of the Earth-Moon Lagrange points, L1 or L2. The entire USOS cannot be reused and will be discarded, but some Russian modules are planned to be reused. "Nauka", the Uzlovoy Module, two science power platforms and "Rassvet", launched between 2010 and 2015 and joined to the ROS, may be separated to form OPSEK. "Nauka" will be used in the station, whose main goal is supporting manned deep space exploration. OPSEK will orbit at a higher inclination of 71 degrees, allowing observation to and from