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
Space weather first spacecraft with the mission of analyzing the space environment. Recent spacecraft include the NASA-ESA Solar-Terrestrial Relations Observatory (STEREO) pair of spacecraft launched in 2006 into solar orbit and the Van Allen Probes, launched in 2012 into a highly elliptical Earth-orbit. The two STEREO spacecraft drift away from the Earth by about 22° per year, one leading and the other trailing the Earth in its orbit. Together they compile information about the solar surface and atmosphere in three dimensions. The Van Allen probes record detailed information about the radiation belts, geomagnetic storms and the relationship between the two. Some spacecraft