Skylab is a space station constructed by NASA in the 1970's, built from Saturn V hardware to save money. A modified docking system was added for an extra LEO cargo module as the space station could only be resupplied with every manned mssion. A second module could be resupplies and when cleared out, useful for storage. By 1980, the space station's orbit was getting dangerously low, with the new space shuttle being set to launch, NASA could not waste any time to save the station. Space Shuttle Discovery sucssfully boosted into a higher orbit and refurbished.