What are two of the limitations of using self-contained breathing apparatus in confined space?

Jacques Cousteau

S.C.U.B.A. or simply scuba.

S.C.U.B.A. duh. . .

The Tank itself must undergo a Hydrostatic Test, External Visual Inspection, Internal Visual Inspection, Valve Test and Assembly Test on a regular basis. The remainder of the equipment has no actual...

1. The cost of manned space missions are higher per mission, meaning less missions.2. Humans are subject to high risks.3.Complex systems must be installed (i.e. life support)4. Humans are restricted...