Browsing by Author "Smith, Melanie"
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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 In-Situ Electrochemical Generation and Utilization of Hydrogen Peroxide for Disinfection(51st International Conference on Environmental Systems, 7/10/2022) Vijapur, Santosh; Hall, Timothy; Taylor, E. Jennings; More, Santosh; Sweterlitsch, Jeffrey; Ewert, Michael; L. Castro-Wallace, Sarah; Byrne, Vicky; Dunbar, Brandon; Nguyen, Hang; Smith, MelanieDisinfection needs to meet personal hygiene requirements at the International Space Station (ISS) is currently accomplished through the use of pre-packaged, disposable, wetted wipes, which represent an appreciable carry-along mass and disposal burden. However, as human missions travel further into the solar system the availability of resources to resupply will be diminished. Therefore, next-generation system should use onboard utilities to create on demand disinfectants thereby reducing the dependence on earth-based supplies and further eliminating storage and disposal problems. Accordingly, we are developing an in-situ approach to electrochemically generate hydrogen peroxide disinfecting solution utilizing onboard life support supplies (Air/Water) to neutralize surface microorganisms present in closed living systems. As discussed within our 2019 and 2021 ICES papers (ICES-2019-38; ICES-2021-273), we have continued to improve our TRL by scaling the electrochemical generation production process and validating the system in a zero-gravity parabolic loop flight test. In this paper/presentation we will demonstrate a system that can achieve over 1 L of 2 w/w% peroxide per day with DI water and air reactor feeds. These electrolytes were then sent to NASA for microbial control property characterization. Overall, the electrochemical peroxide generation system offers a more economical and practical alternative, with the disinfectant being generated on demand and in-situ (using available life support materials (Air/Water)); and applied to reusable cloths. The specific application of interest to this program is crew contact surfaces in space vehicles, but this approach could be utilized for waste water disinfection, heat exchanger biofouling remediation, and laundry applications. The peroxide generation system will also be able to address Earth-based needs in various settings such as field hospitals, restaurants, military, warehouses, movie theatres, among many others. Acknowledgements: Financial support of NASA Contracts No. NNX16CA43P and NNX17CJ12C are acknowledged.Item Microbial Growth Control in the International Space Station Potable Water Dispenser(47th International Conference on Environmental Systems, 2017-07-16) Maryatt, Brandon; Smith, MelanieThe International Space Station (ISS) United States On-orbit Segment currently provides potable water for crew consumption via the Potable Water Dispenser (PWD). The PWD receives iodinated water from the Potable Water Bus, removes the iodine biocide and filters the water for particulates and bacteria, and then dispenses the potable water into an attached food or drink package for consumption. The user can choose to dispense water at either ambient temperature (65°F-123°F [18°C-51°C]) or hot temperature (150°F-200°F [66°C-93°C]). The first PWD unit commenced on-orbit operation in 2009 and has been continually operated since. The second PWD unit completed certification in September 2015 and is to be launched on need when the first PWD unit requires replacement. Until then, the second PWD unit is undergoing periodic maintenance to prevent microbial growth during storage. Each PWD unit poses unique challenges in reducing microbial counts to acceptable levels. The first PWD unit’s effluent is currently sampled on-orbit monthly for coliform bacteria and quarterly for total number of bacterial colony forming units to validate that the system is providing potable water within the limits defined by the NASA ISS Medical Operations Requirements Document. This PWD unit also utilizes operational constraints in the form of Flight Rules to manage off-nominal scenarios (such as prolonged stagnation) requiring the use of high biocide concentrations to “shock” the system to return the unit to its fully serviceable state. The second PWD unit is currently disinfected every 6 months using an iodinated water solution to maintain the bacterial counts within acceptable levels. The disinfection process and timeline has been chosen to reduce the likelihood of unacceptable levels of bacterial growth, minimize the potential for biofilm formation, decrease the potential for corrosion caused by repeated disinfections, and lessen the overall cycling of the PWD unit to preserve hardware life.