Skylab II
Skylab II was a space station concept proposed in 2013 by the Advanced Concepts Office of NASA Marshall Space Flight Center, to be located at the Earth-Moon L2 Lagrangian point. Proposed by NASA contractor Brand Griffin, Skylab II would have been constructed as a "wet workshop" using a spent upper-stage hydrogen fuel tank from the Space Launch System (SLS), much as the Skylab was originally planned to be built "wet" from the spent bipropellant tanks of the Saturn S-IVB upper stage.