Wet workshop

This would make for a cost-effective reuse of hardware that would otherwise have no further purpose, but the in-orbit modification of the rocket stage could prove difficult and expensive.

Since the entire propellant load would be needed to reach orbit, additional life support equipment could not be stored inside the S-II during launch.

During the 1960s, as the Apollo mission transitioned from development to launch, a number of groups inside NASA were studying the post-Apollo era.

However, during the same period of time, on-orbit testing of the Apollo systems was proceeding much better than expected, and a number of proposed shake-down missions were no longer required.

An S-IVB stage could be modified in a fashion similar to von Braun's original proposals, making a smaller but perfectly usable station.

In this case, the equipment would be carried on top of the S-IVB in the location normally reserved for the Lunar Module, but the lack of a large access port meant it would have to remain there instead of being inserted into the tank.

The Saturn V delivered enough impulse in its first two stages to place the complete, ground-built station in orbit, and the design was flown as the Skylab "dry workshop".

Additionally, getting access to the interior was possible though "manholes" used for inspection during construction, but it was not clear if realistic amounts of building materials could have been inserted into the tank after reaching orbit.

NASA contractor Brand Griffin has proposed to the Marshall Space Flight Center's Advanced Concepts Office the building of a station from a spent Space Launch System hydrogen fuel tank, to be placed at the Earth-Moon L2 Lagrangian point and named Skylab II in honor of the original Skylab.