Browsing by Author "Dunbar, Brandon"
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Item Changes in Chemical Composition of ISS Archive Water Samples from Collection to Analysis(49th International Conference on Environmental Systems, 2019-07-07) Wallace, William; Hudson, Edgar; Dunbar, Brandon; Hamilton, Tanner; Wallace, Sarah; Gazda, DanielAnalysis of archive water samples from the International Space Station provides important insight into the performance of the U.S. Water Processor Assembly (WPA). Ensuring the results from these samples accurately represent the chemical composition of the samples as collected on orbit is essential, as this data is used to make decisions regarding the use of on-orbit replacements for WPA components. Recently, samples of effluent from the Multifiltration (MF) beds were collected to determine if the expected breakthrough products (acetate/bicarbonate) were responsible for increased conductivity measured by in-line sensors. Initial results showed the presence of acetate, but the bicarbonate concentration was lower than expected based on the sensor readings, suggesting the possibility of CO2 diffusing through the sample bags. To assess this possibility, a second set of samples were collected in both the standard archive bags and smaller Teflon bags that were subsequently sealed in Mylar to minimize gas permeation. The MF bed 1 effluent sample collected in the standard bags showed breakthrough of a number of expected species, though many were present at lower than anticipated levels. Analysis of samples sealed in Mylar confirmed that gas diffusion had occurred in the standard bag, as the bicarbonate and conductivity readings were both higher than the standard bags. Interestingly, the acetate concentration was also significantly higher. A repeat analysis of the same sample aliquot performed to verify these findings showed no carboxylate species. A fresh aliquot obtained from the sample bag refrigerated in the Mylar pouch showed acetate results close to the original concentrations, but repeat analysis of this aliquot four days later showed no detectable carboxylates. Here, we will discuss efforts to understand the mechanisms that could lead to the compositional changes seen in the archive samples of MF bed effluent, which appear to be dependent on gas diffusion and temperature.Item Culture-Independent Microbial Air Profiling using a Spaceflight-Compatible Nanopore Sequencing Method(51st International Conference on Environmental Systems, 7/10/2022) Dunbar, Brandon; Nguyen, Hang; Stahl-Rommel, Sarah; Sharp, G. Marie; Castro, Christian; Castro-Wallace, SarahMicrobial monitoring of spacecraft air is critical toward assessing the efficacy of microbial controls within the environmental control and life support systems to protect the crew and vehicle environment. Currently, onboard the International Space Station (ISS), the air is monitored on a quarterly basis using an impaction air sampler. With this method, microbial cells and spores are pulled onto plates containing growth medium. Following onboard incubation, the crew reports approximate microbial levels to the ground, but sample return is required for identification. Upon return of the plates, the isolates present are identified for crew health risk assessments. As NASA moves beyond low-Earth orbit, sample return will be impractical, and a near real-time monitoring capability is essential. Significant strides have been made in recent years to utilize a molecular-based method for microbial profiling of ISS surfaces. The developed method is independent of microbial culture, thus removing the bias toward detecting only culturable organisms, eliminates the need for sample return, and reduces risk to crew health from exposure to high microbial levels. The work described here details the evaluation of three different air sampling platforms whose product is amenable to downstream molecular processing. The three samplers were compared in terms of mass and power requirements, ease-of-use, and the resulting data. For the two highest-ranking samplers, a basic concept of operations was developed to transfer the sample into the already established preparation and sequencing process. Using these concepts of operations, an in-depth comparison of the molecular data generated was compared to the historical culture-based method. Data from both methods detailed similar microbial profiles, while the molecular method detailed microbial identifications that were lacking from the culture data. The developed method will enable the generation of near real-time microbial profiles of the spacecraft atmosphere.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 Redefining Spaceflight Microbiology: The Evolution of In Situ Nanopore Sequencing for Microbial Monitoring of Crewed Spacecraft(2024 International Conference on Environmnetal Systems, 2024-07-21) Mena, Christian; Stahl-Rommel, Sarah; Nguyen, Hang; Castro, Christian; Dunbar, Brandon; Rydzak, Patrick; Castro-Wallace, SarahMicrobial monitoring onboard the International Space Station (ISS) is essential to assess risks to both spacecraft and crew. Since human occupation began, onboard microbial culture followed by ground-based analysis has provided data descriptive of a human-occupied environment with fluctuations associated with crew turnover and process escapes from the Environmental Control and Life Support Systems (ECLSS). While this culture-based process has served as the gold standard to alert NASA to anomalies and to provide confidence in the operational controls, the data are biased towards organisms that can be cultured. In 2017, the paradigm that samples had to be returned to Earth for analysis was shifted when unknown microbes, collected and cultured from ISS surfaces, were identified onboard through the use of nanopore sequencing. The following year, culture was removed from the process, and a direct swab-to-sequencer, culture-independent method was validated onboard the ISS. Based on the success of these payloads, the Crew Health Care Systems (CHeCS) BioMole Facility was established. BioMole consists of the hardware, consumables, and procedures needed to support sample preparation and nanopore sequencing. Under the BioMole umbrella, the swab-to-sequencer method and a parallel approach for water analysis has been validated, and a full sample-to-answer process has been demonstrated with the inclusion of onboard data analytics. On the ground, fungal identification and air analysis have also been validated. Just as nanopore sequencing has resulted in the evolution of space-based microbial monitoring, improvements in the technology continue to provide opportunities for further expansion of sequencing capabilities. While previous work (since 2017) has focused on targeted sequencing, metagenomics has emerged as the next phase in environmental sample monitoring using nanopore sequencing. A review of nanopore sequencing for microbial monitoring, as well as the benefits and limitations of metagenomic sequencing, will be discussed here.