Browsing by Author "Wood, William R."
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Item Laser Spectroscopy Multi-Gas Monitor: Results of a Year Long Technology Demonstration on ISS(45th International Conference on Environmental Systems, 2015-07-12) Mudgett, Paul D.; Pilgrim, Jeffrey S.; Wood, William R.Tunable diode laser spectroscopy (TDLS) is an advanced trace and major gas monitoring technology with unmatched selectivity, range and stability. The technology demonstration of the TDLS based Multi-Gas Monitor (MGM), initially reported at the 2014 ICES conference, has been operating continuously on the International Space Station (ISS) for over 15 months as of this writing. The MGM is designed to measure oxygen, carbon dioxide, ammonia and water vapor in ambient cabin air in a low power, relatively compact device. While on board, the MGM experienced a number of challenges, planned and unplanned, including a test of the ammonia channel using a commercial medical ammonia inhalant and carbon dioxide spikes from thruster firings from another payload. Data from the unit was downlinked once per week and compared with other analytical resources on board, notably the Major Constituent Analyzer (MCA), a magnetic sector mass spectrometer. MGM spent the majority of the time installed in the Nanoracks Frame 2 payload facility in front breathing mode, sampling the ambient environment of the Japanese Experiment Module (JEM), but was also used to analyze recirculated rack cooling air. MGM can be operated in portable mode (via internal rechargeable lithium ion polymer batteries or by plugging into any Express Rack 28VDC connector). Results show excellent stability and agreement with MCA data for oxygen and carbon dioxide. The ammonia challenge (~ 75 ppm) was successful as well, showing very rapid response time in both directions. Water vapor results showed weekly spikes corresponding to dry out cycling of JEM condensing heat exchangers and good agreement with dew point measurements in Columbus module. None of the 4 sensor channels has degraded perceptibly to date. Work on expanding the capability in next generation devices has just begun. Target gases include combustion products, formaldehyde and hydrazine. Various hand-held and integrated laser spectroscopy based monitors are envisioned for use on ISS, Orion and Exploration missions.Item Optical Multi-Gas Monitor Technology Demonstration on the International Space Station(44th International Conference on Environmental Systems, 2014-07-13) Pilgrim, Jeffrey S.; Wood, William R.; Casias, Miguel E.; Vakhtin, Andrei B.; Johnson, Michael D.; Mudgett, Paul D.The International Space Station (ISS) employs a suite of portable and permanently located gas monitors to insure crew health and safety. These sensors are tasked with functions ranging from fixed mass spectrometer based major constituents analysis to portable electrochemical sensor based combustion product monitoring. An all optical multi- gas sensor is being developed that can provide the specificity of a mass spectrometer with the portability of an electrochemical cell. The technology, developed under the Small Business Innovation Research program, allows for an architecture that is rugged, compact and low power. A four gas version called the Multi-Gas Monitor was launched to ISS in November 2013 aboard Soyuz and activated in February 2014. The portable instrument is comprised of a major constituents analyzer (water vapor, carbon dioxide, oxygen) and high dynamic range real-time ammonia sensor. All species are sensed inside the same enhanced path length optical cell with a separate vertical cavity surface emitting laser (VCSEL) targeted at each species. The prototype is controlled digitally with a field-programmable gate array/microcontroller architecture. The optical and electronic approaches are designed for scalability and future versions could add three important acid gases and carbon monoxide combustion product gases to the four species already sensed. Results obtained to date from the technology demonstration on ISS are presented and discussed.