International Space Station Environmental Control and Life Support System Mass and Crewtime Utilization In Comparison to a Long Duration Human Space Exploration Mission

Over the last two-and-a-half decades, the International Space Station’s (ISS) Environmental Control and Life Support System (ECLSS) has grown and evolved in size, complexity, and capability. The functions that it performs today are many of those that will need to be performed in the future aboard spacecraft and habitats that will enable long duration human exploration missions to destinations beyond low earth orbit. Regardless of the particular deep space destination, it is widely accepted that highly reliable ECLS systems that depend minimally on expendable equipment will be required. An important question, particularly in today’s fiscally- constrained environment, is how well suited is the ISS ECLSS suite of technologies to meeting the needs of future missions? To help begin answering this question, the maintenance history of the ISS Water Recovery and Oxygen Generation Systems has been surveyed. Equipment mass utilization rates, achieved hardware operating lifetimes, and crewtime spent on maintenance tasks have been tallied to provide a surrogate measure of reliability. These data are also compared to notional targets for a hypothetical three-year Mars mission.