The goal of NASA is to return humans to the surface of the Moon, then journey to Mars and even beyond. To accomplish this, robust life support systems are required to operate without reliance on resupply. The current air revitalization system on the International Space Station (ISS) — the Carbon Dioxide Removal Assembly (CDRA) — utilizes sorbent-based Temperature Swing Adsorption (TSA) technology.
NASA Ames has developed a reliable successor to the state-of-the-art cabin atmosphere CO2 removal system. Spacecraft Atmosphere Carbon Dioxide (CO2) Capture via Deposition is an air revitalization architecture that utilizes the different physical phase-change properties of ISS cabin-like constituents (nitrogen, oxygen, carbon dioxide, water vapor, and various trace contaminants) to selectively separate constituents of interest such as CO2 and trace contaminants.
As the main target constituent is CO2, which does not condense in atmospheric conditions, this architecture is referred to as CO2 deposition, or CDep. The technology addresses future CO 2 removal and life support system needs using a completely different technical approach than currently employed on the ISS. Instead of using a sorbent, this technology utilizes cooling to directly freeze CO2 out of the atmosphere. Specifically, it involves forcing a phase change of CO 2 from the cabin atmosphere by solidifying it onto a cold surface.
This novel patent-pending innovation takes advantage of the condensation/ deposition temperature differences of air components to selectively deposit carbon dioxide from the atmosphere. Deposition coolers can operate in a deposition mode in which CO2 from the airflow is deposited to generate CO2-depleted air and a sublimation mode in which deposited CO2 is sublimated into CO2 gas. The system can alternately cycle between the deposition mode and the sublimation mode. A deposition system can also remove humidity in addition to CO2 via a multi-stage process and can also significantly assist in controlling the trace contaminants.
CDep is highly reliable as it has no expendable materials, no vacuum is required, and needs minimal moving parts. CDep also potentially eliminates the need for a separate storage system to deliver pressurized, pure CO2 to an oxygen generation system such as the Sabatier processor currently on the ISS.