A Comparison of the Apollo and Early Orion Environmental Control, Life Support and Active Thermal Control System's Driving Requirements and System Mass

The Orion Crew and Service Modules are often compared to the Apollo Command and Service Modules due to their similarity in basic mission objective: both were dedicated to getting a crew to lunar orbit and safely returning them to Earth. Both spacecraft rely on the environmental control, life support and active thermal control systems (ECLS/ATCS) for the basic functions of providing and maintaining a breathable atmosphere, supplying adequate amount of potable water and maintaining the crew and avionics equipment within certified thermal limits. This assessment will evaluate the driving requirements for both programs and highlight similarities and differences. Further, a short comparison of the two system architectures will be examined including a side by side assessment of some selected system's hardware mass. This evaluation provides a top level assessment of the efficacy of the Orion ECLS/ATCS, as well as identifies areas that could benefit from a more careful examination as the Orion project approaches the preliminary design review milestone.