U.S. space exploration history on U.S. stamps also the only space station NASA launched alone. The 100-ton space station was in Earth's orbit from 1973 to 1979 and it was visited by crews three times in 1973 and 1974. Circling 50 degrees north and south of the equator at an altitude of , Skylab had an orbital period of 93 minutes. There were a plethora of UV astronomy experiments done during the Skylab lifetime, as well as detailed X-ray studies of the Sun. The station was active until July 11, 1979, when it fell out of orbit. The 10-cent Skylab commemorative stamp first day of release took
International Space Station The hatch leading into the module remains closed except for periodic visits by space station crew members for inspections and data collection. The module was originally planned to be jettisoned from the station following the test, but following positive data after a year in orbit, NASA has suggested that it could remain on the station as a storage area. The International Docking Adapter (IDA) is a spacecraft docking system adapter being developed to convert APAS-95 to the NASA Docking System (NDS) / International Docking System Standard (IDSS). IDA-2 was launched on SpaceX CRS-9 on 18 July 2016. It was attached