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
Center for the Advancement of Science in Space the ISS or partner with the ISSNL to develop new research platforms in space. In addition, the National Lab supports approximately three-dozen privately owned technology companies that provide services to researchers on the Station. This web of researchers and technology companies work together with the staff at the ISSNL to convert terrestrial research into experiments that can be performed in low earth orbit, and to develop and validate new technologies for use on the Station. This model has served the research community well and the ISSNL fully utilizes its 50% allocation of ISS resources. Over the past five years, the