When George Mueller took over as director of NASA’s office of manned space flight in 1963 he set out to ensure that after Apollo had achieved the first lunar landing, the tremendous technical capability developed to achieve this feat should not be wasted. So was born the Apollo Applications Program, and in March of 1966 the first AAP schedule was revealed. It was adventurous to say the least. It projected 45 launches using both the Saturn V and Saturn IB to both Earth and lunar orbits, all of these missions separate from the moon landing effort of Project Apollo. Most significantly, these launches included three Saturn S-IVB Spent Stage Experiment Support Mod­ules (SSESM), otherwise known as “wet workshops’’. This form of space station seemed an economical way for NASA to obtain its first space station experience. The S-IVB stage would be launched to orbit in the normal way as the upper stage of a Saturn V, with a crew in an Apollo CSM, but the spent stage would remain in orbit where it would be dried out internally and outfitted by the crew as a temporary laboratory and workshop. There were some concerns within NASA over this approach, not least within the Astronaut Office, which was primarily concerned with the suitability of a emptied hydrogen tank for human habitation, plus the issues of providing power to the planned experiments, and the general safety of such a structure.

In November 1967 the Manned Spacecraft Center proposed an alternative to the “wet workshop”, a “dry workshop”. This basically meant that instead of launching the S-IVB stage as an active part of the booster and then outfitting it in orbit, the stage should be outfitted on the ground and launched as a conventional payload. However, there was some opposition to this proposal, and it was decided to continue with the wet workshop plan. Things changed again in May 1969; the early success in man-rating the Saturn V had potentially freed up a Saturn V. This reopened the dry workshop possibility. The benefits of being able to completely outfit the workshop on the ground before launch were clear, and Wernher von Braun and his team at Marshall began to warm to the idea that they had originally opposed. In June of that same year, the Department of Defense MOL program was canceled, and several elements including seven of the program’s astronauts, were transferred to NASA. This added new momentum to the Orbital Workshop Program (OWS), as the sole – remaining element of AAP had become known. In July 1969 Apollo 11 landed on the moon, and NASA’s Administrator, Tom Paine, approved the change from wet to dry workshop design, and officially assigned a Saturn V to launch it. The number of AAP launches had now reduced dramatically to just four: one Saturn V to launch the workshop, and three Saturn IB launches to get the crews to the orbiting outpost. In February 1970, the project received an official name; America’s first manned space station would be called Skylab.