NASA astronaut Kevin Ford, Expedition 34 commander, performs maintenance on the Amine Swingbed assembly in the Destiny laboratory of the International Space Station. (NASA TV)
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Amine-based filter beads in Thermally Conductive Metal Foam make up each bed layer of the Carbon dioxide And Moisture Removal Amine Swingbed (CAMRAS). (NASA)
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NASA astronaut Don Pettit, Expedition 31 flight engineer, poses for a photo with the Amine Swingbed assembly during in-flight maintenance in the Harmony node of the International Space Station. (NASA)
View large image Providing breathable, oxygenated air is a necessity and top priority for human exploration spacecraft designers. The ability to remove carbon dioxide (CO2) that humans exhale is just as important. Too much CO2 can cause dizziness, confusion and breathing difficulties for astronauts. The latest technology, the Amine Swingbed, is on the path to being a smaller, capable source of CO2 and moisture removal for future spacecraft. The Amine Swingbed completed its troubleshooting in April, followed by a final leak check and now is ready to move on to a rigorous 1,000 hours of testing.
CO2 is naturally occurring and is the fourth most abundant gas in Earth's atmosphere. It is produced from plant decay, when we exhale and as a result of burning fossil fuels like gas, coal, oil and wood. CO2 also can form as a liquid or a solid, depending on temperature and pressure. Dry ice is the solid form of CO2, changing from a solid back into a gas as it melts. Many factors affect CO2 levels, including the size of the area, number of people and amount of time the area is occupied.
To combat this colorless, odorless gas on the International Space Station, a primary system is in place as part of the Environmental Control and Life Support System. The U.S. portion of the space station has the Carbon Dioxide Removal Assembly (CDRA) and the Russian segment has Vozdukh. Both systems keep the station atmosphere clean of CO2. However, it would be beneficial if a smaller, more efficient unit were available for use with other closed-volume areas like submarines and NASA's new Orion spacecraft. In response to that challenge, engineers developed the Amine Swingbed assembly. This technology is being developed for Orion, and the design will control CO2 levels for a crew of six on the multi-purpose crew vehicle.
The heart of the Amine Swingbed assembly is the Carbon dioxide And Moisture Removal Amine Swingbed (CAMRAS). Hamilton Sundstrand developed the test equipment for the Crew and Thermal Systems Division at NASA's Johnson Space Center in Houston. CAMRAS has several layers of amine-based filter beds that remove carbon dioxide and water vapor from the station's environment. An amine is a nitrogen-containing organic compound. Once the filter beds are full, the assembly rotates to vent CO2 and moisture into space. This venting cleans the filter beds and makes for uninterrupted CO2 removal.
Amine technology is not new. It was tested first on the space shuttle. What makes the CAMRAS filter different is that it is more efficient than the ones used on the shuttle. The system also uses less power and is considerably smaller than the space station's current carbon dioxide removal system. An update to such an assembly for future exploration vehicles could save space and reduce costs.
Since delivery to the space station for testing, there have been issues with the Amine Swingbed assembly's operations. Systems integration is an engineering challenge that often is a necessary and expected part of the innovation and new technology development process. "The CAMRAS itself works fine, as years of ground testing (with and without human test subjects) have demonstrated," said Jeffrey Sweterlitsch, Ph.D., principal investigator for the project within the Life Support Systems Branch at Johnson Space Center. "It is the untested integration of the CAMRAS with all of the other components (which also work fine individually) that created issues." After troubleshooting the system integration issues, NASA is working through a plan to begin testing the swingbed assembly on the space station.
Testing the swingbed assembly's performance and reliability will continue aboard station through Expedition 37/38. This technology could help humans venture further and longer into our solar system by taking up less space, and it also could be used to clean purge-gas supply systems on Earth.