Skylab 1

By 1969, Apollo funding cuts eliminated the possibility of procuring more Apollo hardware, and in fact forced the cancellation of some later Moon landing flights. This freed up at least one Saturn V, allowing the wet workshop to be replaced with the "dry workshop" concept: the station (now known as Skylab) would be built on the ground from a surplus Saturn IB second stage and launched atop the first two live stages of a Saturn V.