CO ₂ Pump for the Space Station Advanced Atmosphere Revitalization Subsystem

The current operation of the International Space Station (ISS) calls for the oxygen used by the occupants to be vented overboard in the form of CO₂, after the CO₂ is scrubbed from the cabin air. Likewise, H₂ produced via electrolysis in the oxygen generator is also vented. NASA is investigating the use of the Sabatier process to combine these two product streams to form water and methane. The water is then used in the oxygen generator, thereby conserving this valuable resource. One of the technical challenges to developing the Sabatier reactor is transferring CO₂ from the Carbon Dioxide Removal Assembly (CDRA) to the Sabatier reactor at the required rate, even though the CDRA and the Sabatier reactor operate on different schedules. One possible way to transfer and store CO₂ is to use a mechanical compressor and a storage tank. Most commercially available compressors, however, use lubricants that are incompatible with the other system components, motors that do not match the ISS power supply, and have acoustic signatures that often exceed the ISS limits. A new oil-free compressor design that overcomes these problems was demonstrated in an earlier study. The adaptation of that design to the ISS Sabatier-based system is described in this paper.