Browsing by Author "Neidholdt, Evan"
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Item Development of the Miniature Total Organic Carbon Analyzer(2024 International Conference on Environmnetal Systems, 2024-07-21) Morrison, Chad; Smith, Melanie; Neidholdt, Evan; Koehler, Zachary; Beechar, Anant; Christensen, Lance; Noell, AaronMonitoring the Total Organic Carbon (TOC) in spacecraft potable water will be of major importance in long-duration human space exploration. In-flight analysis of potable water produced from a regenerative water processor provides immediate feedback on the quality of reclaimed water for crew health as well as water processing system health monitoring. This paper updates the progress in development of the next generation Total Organic Carbon Analyzer (TOCA) designed for the unique requirements of an exploration-class mission. The current objective is to design, build, certify, deliver, and operate a TOCA technology demonstration on the International Space Station (ISS). The next generation analyzer system technology was previously developed and selected among a feasibility study of other options. The new system provides primary advantages of reduced mass and volume through reduced system complexity and reduced need for consumables; therefore, the flight project is named MiniTOCA. The project has recently completed design of the tech demo instrument and assembled and tested a flight-like engineering development unit. The engineering unit has undergone performance testing and environmental testing which provides confidence for the project to move forward with flight unit production and certification activities. Test results are summarized in this paper. The flight unit is targeted for delivery to ISS in late 2025.Item Progress on the Organic and Inorganic Modules of the Spacecraft Water Impurity Monitor, a Next Generation Complete Water Analysis System for Crewed Vehicles(2023 International Conference on Environmental Systems, 2023-07-16) Pensinger, Stuart; Callahan, Michael; Neidholdt, Evan; Noell, Aaron; Oborny, Nathan; Bae, Byunghoon; Lopez, Valeria; Hancock, Bruce; Gonzalez, Marianne; Homer, Margie; Madzunkov, Stojan; Darrach, Murray; Kidd, RichardThe Dragonfly Mass Spectrometer (DraMS) is an instrument on the Dragonfly mission operating on the surface of the Titan, the Saturn’s largest moon. Titan's atmosphere is nitrogen rich and has surface atmospheric pressure of 147 kPa and temperature of 94 K. Since electronics cannot survive at these extreme temperatures, significant thermal isolation is needed between the electronics and the Titan atmosphere to maintain the components above their survival temperatures. However, the main electronic box (MEB) for the DraMS instrument dissipates significant amount of heat over small volume and a conventional conductive cooling approach cannot be used without significant mass additions. Instead, a fan cooled approach was chosen. Conditioned room-temperature air, supplied by the Dragonfly lander, will flow directly over the MEB’s boards during DraMS operational scenarios. A cooling air manifold is designed with the help of computational fluid dynamics (CFD) simulations to effectively distribute the flow over the actively cooled boards. Since the fan will operate at denser-than-Earth pressures on Titan but Earth-like pressures during ground testing, a thermal test was performed to verify the fan’s thermal performance (at varying levels of pressure) and compared against CFD predictions. This test was performed with a 3-D printed mockup of the MEB with heated metallic plates to simulate the circuit boards. This paper will discuss the analytical CFD work and the thermal tests performed to aid the development of the DraMS thermal/mechanical MEB design.Item The Spacecraft Water Impurity Monitor, a Framework for the Next Generation Complete Water Analysis System for Crewed Vehicles Beyond the ISS(51st International Conference on Environmental Systems, 7/10/2022) Kidd, Richard; Homer, Margie; Noell, Aaron; Simcic, Jurij; Bae, Byunghoon; Gonzalez, Marianne; Lopez, Valeria; Darrach, Murray; Pensinger, Stuart; Callahan, Mike; Neidholdt, Evan; Gilbert, NikkiOn-orbit analysis of the total organic carbon (TOC) content of recycled water, as provided by the ISS TOCA, has been an indispensable tool for monitoring the performance of the WRS and for ensuring that water is fit for crew consumption. While TOC has been, and will continue to be an important metric for spacecraft water quality, it provides only limited insight into the total picture. As a measurement, TOC only provides a single �lump sum� quantity of all organic chemicals present in a water sample. Nor does the TOC measurement begin to address inorganic constituents, such as metals resulting from corrosion nor an intentionally-dosed biocide. For exploration missions beyond LEO, the return of water samples to Earth for analysis will be logistically challenging or impossible. The Spacecraft Water Impurity Monitor (SWIM) is a joint collaboration to develop an instrument platform that will perform in-flight measurements and deliver a more complete picture of water quality to decision makers. Eventually, missions to the moon, Mars, and beyond will be equipped with analytical capabilities equaling those found in terrestrial labs. Based on what we know about current and future spacecraft environments, SWIM will seek to provide enhanced analytical capability that enables NASA to confidently send astronauts on distant missions without the possibility of returned water samples. This paper discusses the challenges presented by exploration requirements and the research and development progress toward the goal of a total water analysis system. For organic analysis, one of the analysis technologies that the SWIM team have been developing is a liquid-injection gas chromatograph mass spectrometer system; these systems are the workhorses of analytical chemistry laboratories world-wide. For inorganic analysis, the team is exploring a number of technologies ranging from traditional liquid chromatography technologies (e.g. ion chromatography, capillary electrophoresis) to flight-heritage technology such as ion-specific electrodes.Item TOC Calibration Method for Exploration Application(2024 International Conference on Environmnetal Systems, 2024-07-21) Li, Wenyan; Irwin, Tesia; Wood, Philip; Essumang, Deborah; Diaz, Angie; Azim, Nilab; Callahan, Michael; Morrison, Chad; Neidholdt, EvanTotal organic carbon (TOC) is the amount of carbon associated with organic compounds in solution and is often used as a non-specific indicator for water quality or cleanness. Currently, the Total Organic Carbon Analyzer (TOCA) is being used onboard the International Space Station (ISS) for both water recovery system process control and for human health and performance monitoring. An exploration-class TOCA is now being developed to close the technology gaps between the State-of-the-Art (SOA) ISS TOCA and the emerging requirements of future exploration missions. One of the technical gaps for an exploration TOC analyzer is the development of suitable methods for on-orbit calibration. While the ISS TOCA uses pre-packaged ground-supplied TOC calibration standards, there is limited stability data using this approach. Other options include preparing calibration standards in space, which can be challenging due to the lack of low TOC reagent water. This paper explores the practice of the standard addition method and passive dosing approaches as potential solutions to overcome this problem.