Carbon Dioxide Removal Architectures for Martian Spacesuits

Carbon dioxide removal is a necessary function of spacesuit Portable Life Support Systems, and comprises a significant fraction of overall PLSS mass and volume. The recent development of Rapid Cycle Amine by Johnson Space Center and Collins Aerospace – Space Systems is a promising approach for long-duration missions that removes the need for consumable lithium hydroxide scrubbers. However, this architecture suffers when applied to the Martian environment with its relatively high pressure atmosphere. As the pressure of carbon dioxide at the Martian surface (between 750Pa and 1000Pa) exceeds the safe partial pressure of carbon dioxide inside a spacesuit, simple pressure-swing adsorbent beds cannot provide effective scrubbing. This paper presents and evaluates three approaches for restoring the function of Rapid Cycle Amine or comparable pressure-swing adsorbers in the Martian environment: pressure boosting during the adsorbent bed uptake phase, vacuum boosting during the regeneration phase, and combined temperature/pressure swing during both phases of operation. The size, weight, power and operational implications of each approach are compared against a baseline METOX scrubber to determine the trade space regions where each option is optimal.