|The HI-SEAS habitat stands on the northern slope of Mauna Loa in Hawaii in March. | AFP-JIJI|
The whole point is to see if a small group can get along and continue to function when they are isolated for long periods of time like this. Small groups have been making long voyages on ships sailing on the oceans for a long time, but on those voyages you touch port at least occasionally. Going to Mars you are going to be cut off for years.
Bayou Renaissance Man clued me in.