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
Scientific research on the International Space Station Much like NASA and JAXA, ESA also conducted numerous experiments on the International Space Station. In May 2011, Space Shuttle Endeavour mission STS-134 carried 13 Lego kits to the ISS, where astronauts built models and saw how they reacted in microgravity, as part of the Lego Bricks in Space program. The results were shared with schools as part of an educational project. Scientific research on the International Space Station Scientific research on the International Space Station is a collection of experiments that require one or more of the unusual conditions present in low Earth orbit. The primary fields of research