Browsing by Author "Clark, Kenneth"
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Item Effects of Ambient Alcohol Levels on the Real-time Monitoring of the Atmosphere of the International Space Station(51st International Conference on Environmental Systems, 7/10/2022) Wallace, William; Limero, Thomas; Clark, Kenneth; Gazda, Daniel; Hudson, EdgarMonitoring of the spacecraft environment is required to ensure the health of the crew and the vehicle systems. For the ISS atmosphere, routine volatile organic compound (VOC) monitoring has been performed for almost a decade by Air Quality Monitors (AQMs). The target compounds measured by the AQMs include three types of chemicals: 1) those compounds that would be harmful to crew, 2) those compounds that have been detected regularly in archival samples, and 3) compounds that, while not necessarily harmful to crew health, could present problems for Environmental Control and Life Support Systems (ECLSS). Following the docking of SpaceX-Demo1 (SpX-DM1), the AQMs began to report high levels of isopropanol (IPA). While elevated IPA is routinely observed with visiting vehicles, the level measured by the AQM, and its continued presence following multiple days of scrubbing, caused concerns regarding the U.S. Water Recovery System. Following the departure of SpX-DM1, the IPA levels decreased to nominal levels, allowing the team to investigate the cause of the elevated measurements. Based on the changes in the shape of the gas chromatograph (GC) traces in the IPA region during docked operations, it appeared that an unknown coeluting species was causing problems with quantification. However, with the docking of Northrup-Grumman-11 (NG-11), the elevated IPA returned, as well as the changes in GC traces. In contrast to the SpX-DM1 results, the AQM IPA results did not return to nominal levels following the departure of NG-11, suggesting that the changes could not be tied directly to the visiting vehicle. In this paper, we will discuss a number of potential causes for both the genuine (measured in archival samples) increases in IPA as well as the much higher levels measured by the AQM. Additionally, we will discuss methods being explored to decrease the potential for a reoccurrence in the future.Item Enhanced AQM: Development of an Exploration Compatible Air Quality Monitor(49th International Conference on Environmental Systems, 2019-07-07) Wallace, William; Limero, Thomas; Clark, Kenneth; Macatangay, Ariel; Mudgett, Paul; Gazda, DanielReal-time monitoring of volatile organic compounds (VOCs) on the International Space Station (ISS) is currently performed using a pair of Air Quality Monitors (AQMs), instruments that combine gas chromatography (GC) separation with differential mobility spectrometry (DMS) detection. Each AQM occupies a volume of approximately 4900 cm3 and has a mass of 3.7 kg. Each AQM also requires a power supply that is roughly the same size and mass. While these parameters do not present a concern on the ISS, they are too large for future exploration missions. The most obvious avenue for decreasing the size and mass of the AQMs lies in the reduction from two instruments and power supplies to a single unit and power supply. As currently configured, the required target VOCs cannot be successfully monitored on a single GC column, as the column cannot be cooled sufficiently to allow separation of early-eluting compounds. Here, we will show how limited method changes and additional cooling of the GC column can minimize the effects of compound coelution and allow all analytes to be monitored on a single AQM. We will also discuss other potential improvements that could increase the sensitivity and further reduce the size of an exploration-ready AQM.