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
Orbital station-keeping Global Geoscience WIND satellite—each have annual station-keeping propellant requirements of approximately 1 m/s or less. Earth-Sun —approximately 1.5 million kilometers from Earth in the anti-sun direction—is another important Lagrangian point, and the ESA Herschel space observatory operated there in a Lissajous orbit during 2009–2013, at which time it ran out of coolant for the space telescope. Small station-keeping orbital maneuvers were executed approximately monthly to maintain the spacecraft in the station-keeping orbit. The James Webb Space Telescope needs to use propellant to maintain its halo orbit around the Earth-Sun L2, which provides an upper limit to its designed lifetime: it