High Capacity RCA Sorbents for Increased Cycle Times

NASA is interested in improving the method to control CO2 and water in the Exploration Extravehicular Mobility Unit (xEMU) to meet the ambitious objectives of the Artemis program, which includes human presence on the surface of the Moon and Mars. The technology that is planned to be used is the RCA which utilizes two beds that are alternately used to remove CO2 and H2O and then are regenerated by exposure to space vacuum. The RCA utilizes an amine-based sorbent (SA9T), and although it has good reversible CO2 uptakes, higher capacities are desired to maintain lower CO2 levels and to reduce power consumption and O2 losses. In addition, this sorbent emits low levels of ammonia which must be removed from the suit using a separate technology.nbsp;In the SBIR Phase I project, Reaction Systems successfully developed new sorbents that outperformed SA9T and reduced ammonia emissions. Tests carried out on selected sorbents and SA9T over a wide range of CO2 partial pressures indicated that a new sorbent had cycle times that were over a factor of two greater than for SA9T at the higher CO2 pressures, which results in a 44% reduction in number of half cycles in the Standard EVA. Ammonia emissions are also over an order of magnitude lower for the new sorbent compared to SA9T.nbsp;In the Phase II project, Reaction Systems will continue developing the new sorbent to a TRL that will allow it to be incorporated into new space suits for advanced missions. Tasks include optimizing the composition and preparation, performing lifetime measurements, evaluating the effect that contaminants could have and finally testing at full scale. The full scale tests will be carried out in a custom CO2 control module similar in design to the RCA but will have more accessibility to the sorbent beds. In addition, the module will be installed in Reaction Systemsrsquo; full scale ventilation loop that can simulate pressures, flow rates, and humidity levels encountered in the suit during an EVA.