Major Constituents Analysis for the Vehicle Cabin Atmosphere Monitor
- Saturday, 01 January 2011
Vehicle Cabin Atmosphere Monitor (VCAM) can provide a means for monitoring the air within enclosed environments such as the International Space Station, the Crew Exploration Vehicle (CEV), a Lunar habitat, or another vehicle traveling to Mars. Its miniature preconcentrator, gas chromatograph (GC), and mass spectrometer can provide unbiased detection of a large number of organic species. VCAM’s software can identify whether the chemicals are on a targeted list of hazardous compounds and their concentration. Its 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.
The software processes a sum total spectra (counts vs. mass channel) with the intention of computing abundance ratios for N2, O2, CO2, Ar2, and H2O. A brute-force powerset expansion compares a library of expected mass lines with those found within the data. Least squares error is combined with a penalty term for using small peaks. This permits calibration even in the presence of unexpected/unknown system contamination or unknown/novel ratios of atmospheric constituents.
Automated, reliable mass calibration is a substantial improvement beyond other comparable systems. A method of compensation for variable response component spectra has been utilized via a weighted sum based on the central peak for each expected component.
It is fully autonomous, non-GUI-based,self-calibrating, and compliant with the VXWORKS flight software system.