Skylab was the name of America's first orbiting space station.
It used hardware developed for the Apollo Moon landing including the Command Module and the Saturn V rocket.
The three crews lived on Skylab for the longest space voyages up to that time; for 28, 59, and 84 days each for a total of 117 days.
Skylab traveled a total of 70.5 million miles and completed 2,476 manned orbits of the Earth.
It was the largest habitable structure ever placed into orbit.
Skylab returned harmlessly to Earth on July 11, 1979 after completing 24,181 orbits.
In-orbit repairs to the Skylab proved that men can accomplish much more than programmed machines in space.
It also proved that men can survive for long periods of time in space and helped pave the way for future permanent manned space stations.