Browsing by Author "Williams, Spencer"
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Item Assessment of Biocide Impacts on Life Support and Extravehicular Activity Architectures(50th International Conference on Environmental Systems, 7/12/2021) Abney, Morgan; McCarley, Kevin; Campbell, Colin; Callahan, Michael; Williams, Spencer; Gazda, Daniel; Montgomery, Eliza; Delzeit, Lance; Feather, MartinIodine has historically been used to minimize microbial growth in wetted portions of life support and Exploration Extravehicular Mobility Unit (xEMU) systems. Because of challenges with dormancy, the life support water processing team has baselined silver as a biocide for future Exploration missions, but continues to consider iodine, bromine, and chlorine as options. An assessment was conducted to identify and evaluate the trade space for implementation of various biocides in Lunar surface, Mars transit, and Martian surface vehicles. The team identified sixteen possible biocide sources for use in Exploration systems. An evaluation of the effects of each biocide on crew health, life support hardware, and xEMU hardware was conducted and resulted in eleven potential biocide architectures. Here we report the results of the architecture trade study and recommendations for future investigations.Item Chemical Challenge Tests on ISS Fire Cartridges(2023 International Conference on Environmental Systems, 2023-07-16) Muko, Cristina; Beck, Steven; Wallace, William; Hudson, Edgar; Barrett, Lawrence; Korona, Adam; Williams, Spencer; Gazda, Daniel; Rabel, EmilyFollowing a confirmed combustion event onboard the International Space Station (ISS), crew members will don Emergency Masks, each fitted with 2 ISS fire cartridge filters. As the crew member breathes through the filters, combustion products in the cabin air are either filtered or catalyzed by the fire cartridge media to minimize crew exposure to harmful levels of contaminants. Rigorous certification, acceptance, and surveillance programs for the fire cartridges ensure that each lot meets stringent performance requirements throughout the service life of the cartridges. In accordance with the Quality/Acceptance Test Plan, multiple fire cartridges from each lot undergo chemical challenge tests involving one or more chemicals at specified concentrations. These tests are conducted at specific temperatures, humidity levels, and gas flow rates intended to mimic the worst-case conditions for fire cartridge performance. These challenge tests are conducted by the Environmental Chemistry Laboratory at the NASA Lyndon B. Johnson Space Center. Many of the challenge tests focus on carbon monoxide (CO), but other gases include hydrogen cyanide (HCN), hydrogen chloride (HCl), cyclohexane, acrolein, ammonia (NH3), and acetaldehyde. A fire cartridge is exposed to the test gas in a chamber at the specified conditions, and the outlet is monitored for breakthrough during the 2.5-hour test. This paper will briefly introduce fire cartridges and how they work and will then discuss details of the challenge gas delivery and exposure system, breakthrough monitoring methods, and discussion of issues that have arisen during the course of the test program. Although the focus of this paper will be on the challenge tests, a general summary of the performance of the fire cartridges will also be provided.