2015-10-292015-10-292015-07-12ICES-2015-255http://hdl.handle.net/2346/64508Bellevue, WashingtonBen D. Gardner, UTC Aerospace Systems, USAPhillip M. Erwin, UTC Aerospace Systems, USASouzan Thoresen, UTC Aerospace Systems, USARachel Wiedemann, The Boeing Company, USAChris Matty, NASA Johnson Space Center, USAThe Major Constituent Analyzer is a mass spectrometer based system that measures the major atmospheric constituents on the International Space Station. A number of limited-life components require periodic change-out, including the ORU 02 analyzer and the ORU 08 Verification Gas Assembly. Improvements to ion pump operation and ion source tuning have improved lifetime performance of the current ORU 02 design. The most recent ORU 02 analyzer assemblies, as well as ORU 08, have operated nominally. For ORU 02, the ion source filaments and ion pump lifetime continue to be key determinants of MCA performance and logistical support. Monitoring several key parameters provides the capacity to monitor ORU health and properly anticipate end of life.The 45th International Conference on Environmental Systems was held in Bellevue, Washington, USA on 12 July 2015 through 16 July 2015.engPresentation