A life support system capable of sustaining crew members in an isolated, hostile environment has been designed, fabricated and tested. This system's test was funded by Air Force Systems Command through the Ballistic Missile Office and was designed to demonstrate the technology of a deep underground, remote endurance operational control facility. The three month test involved operation of the habitat under varying external environments to assess the system response. The system design supported physiological requirements such as: recycling waste water, cleansing the atmosphere of internal as well as external contaminants, and providing for emergency operations.Crew members operated the system under simulated peacetime and endurance conditions in order to assess the livability and maintainability of the facility design. The life support equipment was controlled by a dedicated, onboard computer system which monitored the mechanical system performance, altered operational parameters' in response to changing conditions and alerted the crew to potential hazards as well as providing diagnostics for repair. The test demonstrated the feasibility of this preproto-type design for life support by operating without major equipment failures for the duration of the test. Crew members successfully operated the system and were effective in repairing the minor hardware problems which occurred.