More so than most design efforts, a manned spacecraft must be an efficient integration of many subsystems and yet function as an autonomous life support habitat. This document is a brief expose of major determinants affecting extra-terrestrial habitability, subsequently leading to a design proposal for an earth orbiting space station. Owing to the essential integration and mutual dependencies of subsystems, a scheme for the entire station is conceived. Particular emphasis is devoted toward habitability (especially under confined isolation conditions) and serves as a principal generator of the resultant design solution.