Environmental Control and Life Support Systems: Review, Concept, Design, Build, Test of a Carbon Dioxide Removal Testbed to Investigate Degradation and Maintenance in Space Habitats

A vital element of any human-rated mission is the Environmental Control and Life Support System (ECLSS), composed of multiple subsystems, including an Air Revitalization subsystem that maintains a breathable atmosphere. Tracking performance, identifying performance degradation, predicting remaining useful life of components, and performing maintenance on such a critical system are paramount to creating a safe, habitable environment and are thus key research areas at the UC Davis Center for Spaceflight Research. This thesis outlines the design, build, and test of the ZeoDe (Zeolite Capacity Degradation) testbed at the UC Davis Center for Spaceflight research, as well as the background research that went into its conception. This testbed is a chemically functional CO2 removal system that generates degradation data for prognostics through the introduction of humidity into the system. The introduction of humidity can occur in a space habitat due to leaks or other faults. Humidity build-up within the system leads to CO2 removal capacity degradation of the sorbent. Thus, the study of sorbent degradation is of paramount importance to any zeolite-based CO2 removal system deployed on future spacecraft. The maintenance of such a system is equally important. The base requirements of the ZeoDe system take both human and robotic maintainability into account, along with the development of a twin robotically manipulable mockup that was also built up at the UCD Center for Spaceflight Research. The ZeoDe testbed will allow UC Davis, NASA, and any visiting researcher to investigate sensor criticality, degradation physics, detection sequences, and maintenance plans for a degraded ECLSS CO2 removal unit in both autonomous robotic tasks and integrated robot/human teaming scenarios. The modular build will also allow for future research and visiting research to take place at the center to further ECLSS research for future space habitation.