Browsing by Author "Meyer, Marit E."
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Item Characterization of carbon particulates in the exit flow of a Plasma Pyrolysis Assembly (PPA) reactor(45th International Conference on Environmental Systems, 2015-07-12) Green, Robert D.; Meyer, Marit E.; Agui, Juan H.; Berger, Gordon M.; Vijayakumar, R.; Abney, Morgan B.; Greenwood, ZacharyThe ISS presently recovers oxygen from crew respiration via a Carbon Dioxide Reduction Assembly (CRA) that utilizes the Sabatier chemical process to reduce captured carbon dioxide to methane (CH4) and water. In order to recover more of the hydrogen from the methane and increase oxygen recovery, NASA Marshall Space Flight Center (MSFC) is investigating a technology, plasma pyrolysis, to convert the methane to acetylene. The Plasma Pyrolysis Assembly (or PPA), achieves 90% or greater conversion efficiency, but a small amount of solid carbon particulates are generated as a side product and must be filtered before the acetylene is removed and the hydrogen-rich gas stream is recycled back to the CRA. In this work, we present the experimental results of an initial characterization of the carbon particulates in the PPA exit gas stream. We also present several potential options to remove these carbon particulates via carbon traps and filters to minimize resupply mass and required downtime for regeneration.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 Measurement of Fungi and Bacteria from Dust Collected on the International Space Station (ISS)(49th International Conference on Environmental Systems, 2019-07-07) Haines, Sarah R.; Bope, Ashleigh; Nastasi, Nick; Horack, John M.; Meyer, Marit E.; Dannemiller, Karen C.Exposure to fungi and bacteria can have important implications for human health. This is especially true on spacecraft, where astronauts may experience changes to their immune system. However, we do not understand how distribution of fungi and bacteria in different particle size fractions of dust in microgravity may impact human exposure. The goal of this work was to develop methods to characterize the microorganisms in different particle size fractions and in a passive sampler from dust collected on the International Space Station (ISS). Dust was analyzed from both a vacuum bag sample and a passive aerosol collector for both fungi and bacteria using DNA-based techniques. The passive aerosol sample consisted of a piece of double-sided black carbon sticky tape that was exposed to the air in ISS Node 3 for 16 days. We were able to obtain both bacterial and fungal DNA from both the passive sampler and the vacuum bag dust. To determine the percent recovery of cells and spores on the passive aerosol sample a 3 cm2 piece of black carbon tape was spiked with 10uL of Aspergillus fumigatus at a concentration of 2.164 x 106 spores/µL and 10µL of Bacillus atrophaeus at a concentration of 7.76 x 107 cells/µL. This spiked tape was extracted along with a blank sample of tape and a sample of A. fumigatus and B. atrophaeus. We divided the quantity of spores or cells recovered from the spiked tape sample by the amount recovered from the sample of A. fumigatus and B. atrophaeus and determined a 90% recovery of fungal spores and a 73% recovery of bacterial cells. Overall, we developed methods to analyze fungi and bacteria in dust from the ISS, which will be used in the HUMID study to consider microbial growth. Our results will have implications for future system design.Item Qualification of a Multi-Channel Infrared Laser Absorption Spectrometer for Monitoring CO, HCl, HCN, HF, and CO2 Aboard Manned Spacecraft(45th International Conference on Environmental Systems, 2015-07-12) Briggs, Ryan M.; Frez, Clifford; Forouhar, Siamak; May, Randy D.; Meyer, Marit E.; Kulis, Michael J.; Berger, Gordon M.Monitoring of specific combustion products can provide early-warning detection of accidental fires aboard manned spacecraft and also identify the source and severity of combustion events. Furthermore, quantitative in situ measurements are important for gauging levels of exposure to hazardous gases, particularly on long- duration missions where analysis of returned samples becomes impractical. Absorption spectroscopy using tunable laser sources in the 2 to 5 μm wavelength range enables accurate, unambiguous detection of CO, HCl, HCN, HF, and CO2, which are produced in varying amounts through the heating of electrical components and packaging materials commonly used aboard spacecraft. Here, we report on calibration and testing of a five-channel laser absorption spectrometer designed to accurately monitor ambient gas-phase concentrations of these five compounds, with low-level detection limits based on the Spacecraft Maximum Allowable Concentrations. The instrument employs a two-pass absorption cell with a total optical pathlength of 50 cm and a dedicated infrared semiconductor laser source for each target gas. We present results from testing the five-channel sensor in the presence of trace concentrations of the target compounds that were introduced using both gas sources and oxidative pyrolysis (non-flaming combustion) of solid material mixtures.