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
Plants in space plants in space, were the trees on the brick moon space station, in the 1869 short story "The Brick Moon". In the 2010s there was an increased desire for long-term space missions, which lead to desire for space-based plant production as food for astronauts. An example of this is vegetable production on the International Space Station in Earth orbit. By the year 2010, 20 plant growth experiments had been conducted aboard the international Space Station.. Several experiments have been focused on how plant growth and distribution compares in micro-gravity, space conditions versus Earth conditions. This enables scientists to explore whether