Browsing by Author "Mudgett, Paul D."
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Item 2014 ISS Potable Water Characterization and Continuation of the Dimethylsilanediol Chronicle(45th International Conference on Environmental Systems, 2015-07-12) Straub, John E. II; Plumlee, Debrah K.; Mudgett, Paul D.During 2014 the crews from Expeditions 38-41 were in residence on the International Space Station (ISS). In addition to the U.S. potable water reclaimed from humidity condensate and urine, the other water supplies available for their use were Russian potable water reclaimed from condensate and Russian ground- supplied potable water. Beginning in June of 2014 and for the fourth time since 2010, the product water from the U.S. water processor assembly (WPA) experienced a rise in the total organic carbon (TOC) level due to organic contaminants breaking through the water treatment process. Results from ground analyses of ISS archival water samples returned on Soyuz 38 confirmed that dimethylsilanediol was once again the contaminant responsible for the rise. With this confirmation in hand and based upon the low toxicity of dimethylsilanediol, a waiver was approved to allow the crew to continue to consume the water after the TOC level exceeded the U.S. Segment limit of 3 mg/L. Several weeks after the WPA multifiltration beds were replaced, the TOC levels returned to below the method detection limit of the onboard TOC analyzer (TOCA) as anticipated based upon experience from previous rises. This paper presents and discusses the chemical analysis results for the ISS archival potable-water samples returned in 2014 and analyzed by the Johnson Space Center’s Toxicology and Environmental Chemistry laboratory. These results showed compliance with ISS potable water quality standards and indicated that the potable-water supplies were acceptable for crew consumption. Although dimethylsilanediol levels were at times elevated, they remained well below the 35 mg/L health limit so the continued consumption of the U.S. potable water was considered a low risk to crew health and safety. Excellent agreement between in-flight and archival sample TOC data confirmed that the TOCA performed optimally and continued to serve as a vital tool for monitoring organic breakthrough and planning remediation action.Item Heating of Printed Circuit Board, Wire Insulation and Electronic Components for Fire Signature Sensor Evaluation(44th International Conference on Environmental Systems, 2014-07-13) Kulis, Michael J.; Meyer, Marit E.; Mudgett, Paul D.; Berger, Gordon M.; Pilgrim, Jeffrey S.This paper describes the results of tests to identify optimal chemical markers for augmenting particle-based fire detection methods. The tests were conducted at the NASA Glenn Research Center’s Gases and Aerosols from Smoldering Polymers (GASP) facility, a custom 326 liter smoke chamber designed for containing smoke resulting from the heating of materials in a tube furnace. Materials used in this investigation included blank printed circuit boards, polyvinyl chloride and polytetrafluoroethylene/polyimide wire insulation, and various surface mount electronic components used intact to simulate realistic fire scenarios. Two different heating rates were applied during the testing of each set of fuels. A commercially available smoke detector and hand-held chemical monitors were located inside the smoke chamber. Instruments for smoke particle characterization and a Fourier transform infrared spectrometer were plumbed from the outside of the smoke chamber. The time response of the commercially available smoke detector was compared to the time response of chemical monitors and an optical acid gas monitor while heating the material at slow and fast rates. Of particular interest was the dependency of the acid gas product concentrations on the heating conditions and sample material. Results are presented and discussed along with implications for spacecraft fire safety and design of future combustion product monitors.Item International Space Station Potable Water Characterization for 2013(44th International Conference on Environmental Systems, 2014-07-13) Straub, John E.; Plumlee, Debrah K.; Schultz, John R.; Mudgett, Paul D.In this post-construction, operational phase of International Space Station (ISS) with an ever-increasing emphasis on its use as a test bed for future exploration missions, the ISS crews continue to rely on water reclamation systems for the majority of their water needs. The onboard water supplies include U.S. Segment potable water from humidity condensate and urine, Russian Segment potable water from condensate, and ground-supplied potable water, as reserve. In 2013, the cargo returned on the Soyuz 32-35 flights included archival potable water samples collected from Expeditions 34-37. The former Water and Food Analytical Laboratory (now Toxicology and Environmental Chemistry Laboratory) at the NASA Johnson Space Center continued its long-standing role of performing chemical analyses on ISS return water samples to verify compliance with potable water quality specifications. This paper presents and discusses the analytical results for potable water samples returned from Expeditions 34-37, including a comparison to ISS quality standards. During the summer of 2013, the U.S. Segment potable water experienced a third temporary rise and fall in total organic carbon (TOC) content, as the result of organic contamination breaking through the water system’s treatment process. Analytical results for the Expedition 36 archival samples returned on Soyuz 34 confirmed that dimethylsilanediol was once again the responsible contaminant, just as it was for the previous comparable TOC rises in 2010 and 2012. Discussion herein includes the use of the in-flight total organic carbon analyzer (TOCA) as a key monitoring tool for tracking these TOC rises and scheduling appropriate remediation.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 Monitoring of the Atmosphere on the International Space Station with the Air Quality Monitor(47th International Conference on Environmental Systems, 2017-07-16) Wallace, William T.; Limero, Thomas F.; Loh, Leslie J.; Mudgett, Paul D.; Gazda, Daniel B.During the early years of human spaceflight, short duration missions allowed for monitoring of the spacecraft environment to be performed via archival sampling, in which samples were returned to Earth for analysis. With the construction of the International Space Station (ISS) and the accompanying extended mission durations, the need for enhanced, real-time monitors became apparent. The Volatile Organic Analyzer (VOA) operated on ISS for 7 years, where it assessed trace volatile organic compounds in the cabin air. The large and fixed-position VOA was eventually replaced with the smaller Air Quality Monitor (AQM). Since March 2013, the atmosphere of the U.S. Operating Segment (USOS) has been monitored in near real-time by a pair of AQMs. These devices consist of a gas chromatograph (GC) coupled with a differential mobility spectrometer (DMS) and currently target detection list of 22 compounds. These targets are of importance to both crew health and the Environmental Control and Life Support Systems (ECLSS) on ISS. Data is collected autonomously every 73 hours, though the units can be controlled remotely from mission control to collect data more frequently during contingency or troubleshooting operations. Due to a nominal three-year lifetime on-orbit, the initial units were replaced in February 2016. This paper will focus on the preparation and use of the AQMs over the past several years. A description of the technical aspects of the AQM will be followed by lessons learned from the deployment and operation of the first set of AQMs. These lessons were used to improve the already-excellent performance of the instruments prior to deployment of the replacement units. Data trending over the past several years of operation on ISS will also be discussed, including data obtained during a survey of the USOS modules. Finally, a description of AQM use for contingency and investigative studies will be presented.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.