Histogrammatic Method for Determining Relative Abundance of Input Gas Pulse
- Tuesday, 01 May 2012
To satisfy the Major Constituents Analysis (MCA) requirements for the Vehicle Cabin Atmosphere Monitor (VCAM), this software analyzes the relative abundance ratios for N2, O2, Ar, and CO2 as a function of time and constructs their best-estimate mean. A histogram is first built of all abundance ratios for each of the species vs time. The abundance peaks corresponding to the intended measurement and any obfuscating background are then separated via standard peak-finding techniques in histogram space. A voting scheme is then used to include/exclude this particular time sample in the final average based on its membership to the intended measurement or the background population. This results in a robust and reasonable estimate of the abundance of trace components such as CO2 and Ar even in the presence of obfuscating backgrounds internal to the VCAM device.VCAM can provide a means for monitoring the air within the enclosed environments, such as the ISS (International Space Station), Crew Exploration Vehicle (CEV), a Lunar Habitat, or another vehicle traveling to Mars. Its miniature pre-concentrator, gas chromatograph (GC), and mass spectrometer can provide unbiased detection of a large number of organic species as well as MCA analysis. VCAM’s software can identify the concentration of trace chemicals and whether the chemicals are on a targeted list of hazardous compounds. This innovation’s performance and reliability on orbit, along with the ground team’s assessment of its raw data and analysis results, will validate its technology for future use and development.
This work was done by Lukas Mandrake, Benjamin J. Bornstein, Stojan Madzunkov, and John A. MacAskill of Caltech for NASA’s Jet Propulsion Laboratory.