Hab Commander
From OCE Space Simulation
The habitat, or "hab" commander is the head astronaut in the habitat. He has total control within the habitat and is the highest on the blame list. He is still, however, under the direct control of Mission Control and the the Mission Control Commander.
Ussualy, though not always, the Mission Commander who happens to be an astronaut is appointed this task. However, when both mission commanders decide to work in mission control, a seperate habitat commander is chosen.