Journal Article
International Space Station (ISS) Major Constituent Analyzer (MCA) On-Orbit Performance
2008-06-29
2008-01-1971
This paper summarizes the first seven plus years of on-orbit operation for the Major Constituent Analyzer (MCA). The MCA is an essential part of the International Space Station (ISS) Environmental Control and Life Support System (ECLSS). The MCA is a mass spectrometer instrument in the US Destiny Laboratory Module, which provides critical monitoring of six major atmospheric constituents (nitrogen (N2), oxygen (O2), hydrogen (H2), carbon dioxide (CO2), methane (CH4), and water vapor (H2O)). These gases are sampled continuously and automatically in all United States On Orbit Segment (USOS) modules via the ISS Sample Delivery System (SDS). Continuous readout of the partial pressures of these gases is critical to verifying safe operation of the Atmosphere Re-vitalization (AR) system, Atmosphere Control System (ACS), and crew safety for Airlock Extravehicular Activity (EVA) preparation.