International Space Station Carbon Dioxide Removal Assembly (ISS CDRA) Troubleshooting and Evaluation

An important aspect of air revitalization for life support in spacecraft is the removal of carbon dioxide from cabin air. Several types of carbon dioxide removal systems are in use in spacecraft life support. These systems rely on various removal techniques that employ different architectures and media for scrubbing CO₂, such as permeable membranes, liquid amine, adsorbents, and absorbents. Sorbent systems have been used since the first manned missions. The current state of key technology is the existing International Space Station (ISS) Carbon Dioxide Removal Assembly (CDRA), a system that selectively removes carbon dioxide from the cabin atmosphere. The CDRA system was launched aboard UF-2 in February 2001 and resides in the U.S. Destiny Laboratory module. During the past three years, the CDRA system has operated with varying degrees of success. This paper presents some of the troubleshooting that occurred, and discusses the results of the Test, Teardown, and Evaluation of the ORUs that were returned from orbit. Approaches to troubleshooting the CDRA system aimed at developing work-around solutions that would minimize the impact on astronaut time required to implement interim solutions. The paper also discusses short-term fixes applied to promote hardware life, restore functionality, and maintain system operability, as well as long-term solutions to prevent future malfunctions.