Browsing by Author "Calle, Luz"
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Item Corrosion on Mars: An Investigation of Corrosion under Relevant Simulated Martian Environments(48th International Conference on Environmental Systems, 2018-07-08) Calle, Luz; Li, Wenyan; Buhrow, Jerry; Johansen, Michael; Calle, CarlosThe goal of this research is to develop a systematic approach to understand corrosion of spacecraft materials on Mars by conducting a literature search of available data relevant to corrosion in the Mars environment and by performing preliminary laboratory experiments under relevant simulated Martian conditions. This project was motivated by the new found evidence for the presence of transient liquid brines that coincided with the suggestion by a team of researchers that some structure degradation cannot be attributed to rock scratching and may be caused by corrosive interactions of brines with spacecraft materials. An extensive literature search on data relevant to Mars corrosion confirmed the need for further investigation of the effect of the Mars environment on the materials used for spacecraft and structures designed to support long-term surface operations on Mars. Simple preliminary experiments, designed to look at the interaction between AA7075-T73 aluminum alloy and the gases present in the Mars atmosphere, at 20 degree C and a pressure of 633 Pa, showed that there is a significant interaction between the small amount of oxygen present in the Mars gas and the alloy when there is a scratch that removes the protective aluminum oxide film. There are many other important components of the Mars environment that can affect this interaction such as: the photo-catalytic effect of radiation on the oxidizing species, and the effect of salts in Martian soil. These initial experimental results provide strong justification for further investigation of the corrosion mechanism of materials relevant to long-term surface operations in support of future human exploration missions on Mars.Item Demonstration of the International Space Station Particle Database Website(51st International Conference on Environmental Systems, 7/10/2022) Tuya, Nathalie; Li, Wenyan; Calle, Luz; Meyer, Marit; Sorek-Hamer, Meytar; Hallinan, IrinaNASA has continuously emphasized the importance of allowing the public to interact and engage with its missions and initiatives by using open-source data. As a result of the large dataset gathered during the International Space Station (ISS) aerosol sampling missions, the ISS Aerosol Sampling Experiment Web Application was developed. This application allows users to easily plot and visualize data from the 2016 and 2018 aerosol experiments. This tool is an open-source and public-facing website, allowing anyone to easily plot the ISS aerosol data in order to develop their own research and conclusions. This platform allows for plotting and visualization of particle composition, geometry, morphology, sampling durations, and collection locations. The tool features an elemental composition pie chart, a plot tool, and an interactive plot tool. The work presented on this paper involves a demonstration of how this Web Application was used to show the morphology of aluminum-chlorine-zirconium particles as well as the presence of lead particles on Node 3 and Node 2 of the ISS.Item Effects of Surface Treatments on Stainless Steel 316 Exposed to Potable Water Containing Silver Disinfectant(49th International Conference on Environmental Systems, 2019-07-07) Li, Wenyan; Buhrow, Jerry; Diaz, Angie; Irwin, Tesia; Calle, Luz; Callahan, MichaelSilver has been selected as the forward disinfectant candidate for potable water systems in future space exploration. To develop a reliable antibacterial system that requires minimal maintenance, it is necessary to address relevant challenges to preclude issues for future missions. One such challenge is silver depletion in potable water systems. When in contact with various materials, silver ions can be easily reduced to its metallic state or form insoluble compounds. The same chemical properties that make silver a powerful antimicrobial agent also result in its quick inactivation or depletion in various environments. Different metal surface treatments, such as thermal oxidation and electropolishing, have been investigated for their effectiveness in reducing the depletion of silver disinfectant from potable water. However, their effects on the metal surface microstructure and chemical resistance have not often been included in the studies. This paper reports the effect of surface treatments on SS316 exposed to potable water containing silver ion disinfectants. Early experimental results showed that thermal oxidation, when compared to electropolishing, resulted in a thicker oxide layer and a compromised corrosion resistance of the SS316.Item Fate of Silver Biocide on the International Space Station Living Environment(50th International Conference on Environmental Systems, 7/12/2021) Ley, Sarah; Li, Wenyan; Rodell, Amanda; Meyer, Marit; Calle, Luz; Lersch, Traci; Bunker, Kristin; Casuccio, GaryPreventing microbial growth within crewed spacecraft water systems is a primary concern to ensure the health and safety of the crew and protect onboard equipment. Silver is being considered by NASA as a biocide replacement for iodine in the International Space Station (ISS) water system. Iodine is currently used but must be removed from the water before crew consumption due to health concerns related to iodine absorption. Aboard the ISS, several systems currently utilize silver as a biocide, including the Russian Orbital Segment (ROS) water system, which incorporates silver ions, and the US Orbital Segment (USOS) heat exchangers, which utilize a silver salt to prevent microbial development. A recent collection of airborne particles on the ISS showed the presence of silver particles, motivating an investigation into their source and the possibility of their unintentional escape into the air. As the ISS is a closed system, it is vital to determine the composition and concentration of potentially harmful particles in the environment. This paper concerns a literature review conducted to further understand the fate of silver biocide in space and, more specifically, aboard the ISS.Item Investigation into Simulated Microgravity Techniques Used to Study Biofilm Growth(51st International Conference on Environmental Systems, 7/10/2022) Diaz, Angie; Li, Wenyan; Irwin, Tesia; O'Rourke, Aubrie; Calle, Luz; Hummerick, Mary; Khodadad, Christina; Gleeson, Jonathan; Callahan, MichaelBacterial growth in liquid media in microgravity conditions is not well understood. Trends such as a shortened lag phase, longer log phase, slower growth rate, and a higher final population concentration have been noted but the underlying cause remains unclear. At the single cell level, it is predicted that bacteria are less gravity-sensitive than larger species. The effects on their immediate environment, including the lack of cell settlement and slower mass transfer of nutrients due to lack of density driven convection, could help explain the trends. Ground-based spaceflight analogs, or simulated microgravity devices, are often employed to achieve different attributes of weightlessness to study effects on bacterial growth. Though these technologies could isolate gravity�s role in various biological processes, they cannot replicate all its effects and underlying mechanisms. Hence, interpretation of results could be misleading, even if similar to spaceflight. In this study two common simulated microgravity devices were investigated to determine whether they could simulate relevant microgravity conditions for bacterial growth. A bioreactor, the high aspect ratio vessel (HARV), was used with dyes of different density mounted on a random positioning machine (RP machine) or a rotating wall vessel (RWV). The RP machine displayed higher mixing rates than the RWV. The RWV was further tested at different rotations per minute (RPM). The range to minimize effects of density driven convection (low speeds) or centrifugal forces (high speeds) was between a range of 15-20 RPM. These results will help inform the selection of simulated microgravity device as well as interpretation of subsequent biofilm growth results.Item Investigation of Biofilm Formation and Control for Spacecraft - An Early Literature Review(49th International Conference on Environmental Systems, 2019-07-07) Diaz, Angie; Li, Wenyan; Calle, Luz; Callahan, Michael; Irwin, TesiaBacterial biofilms are an important and often problematic aspect of life on earth and in space. Biofilms of opportunistic pathogenic bacteria can lead to severe and costly contamination problems that directly affect human health and long-term mission planning. Microbial contamination on board the International Space Station (ISS) continues to pose mission risks, both to crew health and hardware reliability. In order to optimize the design of future space exploration vehicles, a thorough understanding of biofilm formation and control technologies is needed to control the habitat’s microbial environment. This paper provides a literature review on microbial behavior, biofilm formation in spacecraft or simulated spacecraft environments, and the state of the art of biofilm prevention mechanisms.Item Investigation of Silver Biocide as a Disinfection Tehcnology for Spacecraft – An Early Literature Review(48th International Conference on Environmental Systems, 2018-07-08) Li, Wenyan; Calle, Luz; Hanford, Anthony; Stambaugh, Imelda; Callahan, MichaelAn ideal spacecraft water disinfection system should prevent or control microbial growth, inhibit or prevent biofilm formation, and prevent microbial-induced corrosion. In addition, the selected biocide system should be chemically compatible with materials used in the water storage and distribution system, have minimal maintenance requirement, especially for long-duration missions, and should be safe for crew consumption at levels appropriate for biocidal control. Silver ion is a proven broad spectrum biocide. Terrestrially, there has been an increased interest in the biocidal function of silver, both due to its potential to control bacterial resistant species and due to advances in silver and nano-silver biocide technologies. NASA is considering silver as the future biocide for exploration over the current iodine state-of-the-art (SOA) biocide system. In order to select and design a successful silver biocide delivery system to meet NASA’s requirements, it is essential to understand the advantages and disadvantages of moving to a silver disinfection system. To enhance the knowledge base for the application of silver biocides in spacecraft water systems, this paper provides a first compilation of review data related to: (1) Silver as a biocide technology, (2) Options and concepts for silver biocide delivery, and (3) Silver biocide compatibility studies for spacecraft systems.Item A Literature Review of Antifouling Surfaces and Treatments for Long-term Synergistic Biofilm Control(2020 International Conference on Environmental Systems, 2020-07-31) Diaz, Angie; Li, Wenyan; Irwin, Tesia; Calle, Luz; Callahan, MichaelBiofilm prevention and control are needed for spacecraft water storage and distribution systems for long duration exploration missions. One way of preventing biofilm formation involves the use of surface treatments. However, antifouling surfaces have a limited lifespan because microbes alter the surface properties and reduce their antifouling function over time. Surface treatment requires a maintenance strategy to extend the lifespan of the antifouling surface. This study aims to give an overview of state-of-the-art technologies for antifouling and maintenance methods that can be considered when developing Synergistic Biofilm Control (SyBiCo) method for spacecraft water systems.Item Literature Review of Disinfection Techniques For Water Treatment(2020 International Conference on Environmental Systems, 2020-07-31) Azim, Nilab; Diaz, Angie; Li, Wenyan; Irwin, Tesia; Calle, Luz; Callahan, MichaelWater treatment is a developing concern, both terrestrially and in spacecraft, as exploration missions extend in time and distance. Current biofilm control is limited for long-term applications. To optimize biocides for present and future space exploration vehicles, a thorough understanding of common and traditional disinfectant techniques is required. This review is focused on the three fundamental disinfection techniques: chemical, physical, and biological. Mechanisms, advantages, disadvantages, and specific properties of each major technique, as well as their studied effect on established biofilms, are also considered. This paper provides a general background on disinfectants and some information on effects on biofilms that can be useful to develop innovative ideas for state-of-the-art disinfection techniques for water treatment in specific environments, such as those currently posing mission risks as well as for future spacecraft water system development.Item Long-Term Survival of Bacteria under Dormancy Conditions: A Preliminary Review(50th International Conference on Environmental Systems, 7/12/2021) Li, Wenyan; Diaz, Angie; Irwin, Tesia; Calle, Luz; Velez Justiniano, Yo-Ann; Angle, Geoffrey; Johnson, Alexander; Callahan, MichaelBiofilm mitigation and biomass control can be challenging in wastewater processing systems, such as those onboard the International Space Station (ISS). Understanding bacterial behavior, under dormancy conditions, becomes critical as mission duration extends and long periods of dormancy become an integral state of the wastewater system. The objective of this review on the current state of knowledge on the long-term starvation and survival behavior of bacteria is to provide a useful insight for the ongoing long-term bacterial dormancy studies.Item Microgravity Effect on Bacterial Growth: A Literature Review(51st International Conference on Environmental Systems, 7/10/2022) Li, Wenyan; Diaz, Angie; Irwin, Tesia; Orourke, Aubrie; Calle, LuzGravity is a well-known, but little understood, physical force. It interacts with other physical environmental factors to impact the formation of today's Earth, and to contribute to biological variations between water and land species. It is also involved with cell differentiation process, and is responsible for setting the boundaries for life and keeping the cells small. With their simple structures and small sizes, microbes are expected to be less gravity sensitive than larger species. Nevertheless, various effects of space flight on bacterial growth have been reported, but the reports have been sometime inconsistent, and the underlying mechanism remains unclear to many. This paper summarize the systematic efforts to evaluate the effect of space flight on microbial growth, while highlighting the extracellular mass transfer mechanism: bacterial growth is a function of intracellular and environmental factors; the availability of the nutrients and the removal of metabolic by-products, through extracellular mass transfer, are the most important ones. Gravity results in cell settlement and induces density-driven convection within the fluid media, thus impacts the bacterial growth indirectly through the extracellular mass transfer process; where the immediate, direct influence of gravity might otherwise deem negligible.Item A Preliminary Modeling Study of Biofilm Accumulation in the Water Recovery System(2020 International Conference on Environmental Systems, 2020-07-31) Diaz, Angie; Li, Wenyan; Irwin, Tesia; Calle, Luz; Angle, Geoffrey; Velez Justiniano, Yo-Ann; Nur, Mononita; Callahan, MichaelBacterial biofilms are ubiquitous in wastewater systems on earth and in spacecraft, such as in the International Space Station (ISS) wastewater processing assembly (WPA), where they cause problems in the tank, solenoid valves, and pipelines. Downstream filter applications, tank cycling, and regular biocide water flushing have been used to control biofilm accumulation on board the ISS. Biofilm control is expected to be a challenge for long-term missions with a dormancy period of up to a year, as stagnant water systems are highly susceptible to biofilm growth. Flushing of the system with biocidal water has been proposed to avoid biomass problems for long-term missions. To validate the proposed flush method, a mathematical model, based on the metabolism maintenance rate of bacteria, is being developed to understand the current biofilm accumulation rate in the ISS WPA system and to calculate the biomass production rate under dormancy-like conditions. This method of quantification of biofilm can be applied as a function of nutrient inputs to guide the selection and optimization of biofilm mitigation approaches. The method can also be helpful in understanding, defining, quantifying, visualizing, and simulating the state of the water processing system during operation and after dormancy.Item Presence of Metal Aerosols on the International Space Station(51st International Conference on Environmental Systems, 7/10/2022) Rodell, Amanda; Li, Wenyan; Calle, Luz; Meyer, MaritDuring 2016 and 2018 Passive Aerosol Samplers (PAS) were placed on vents and filters around the United States Orbital Segment (USOS) of the International Space Station (ISS). Once the samples were collected, they were sent back to earth for analysis using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). This analysis provided size, morphology, and elemental compositions of the individual aerosol particles that were collected. Using filter area, vent flow rate, and the concentration of particles on the samples the airborne concentration was calculated and compared to the standards set by the Occupational Safety and Health Administration (OSHA). All the atmospheric elemental concentrations on the ISS were below 1% of their corresponding OSHA standards. While this analysis does provide us with the first estimate of aerosol levels on the ISS, there are several assumptions that were made throughout this process and further research will be required to validate these assumptions.Item Silver Foam as Long-Term Passive Biocide to Potable Water Systems(49th International Conference on Environmental Systems, 2019-07-07) Irwin, Tesia; Li, Wenyan; Buhrow, Jerry; Diaz, Angie; Calle, Luz; Callahan, MichaelSilver is being considered as the biocide for future exploration missions. Maintaining microbial control in spacecraft potable water storage and delivery systems is a significant challenge for long-duration human space exploration. The current electrolytic-based silver ion dosing system still has some challenges to be addressed and there is a need for a reliable passive silver biocide delivery mechanism. This paper describes the early stage development of a silver-based composite foam as an alternative silver dosing release technology, either to be used as a standalone, or in conjunction with the electrolytic-based systems to increase the overall system reliability. Composite foam, containing silver chloride nano particles, was synthesized and its structural properties and silver ion release rate are being optimized. This paper concerns the design, synthesis, and optimization of the silver composite foam.Item Silver Foam: A Novel Approach for Long-Term Passive Dosing of Biocide in Spacecraft Potable Water Systems -- Update 2022(51st International Conference on Environmental Systems, 7/10/2022) Irwin, Tesia; Li, Wenyan; Diaz, Angie; Calle, Luz; Callahan, MichaelA spacecraft water disinfection system, suitable for extended length space exploration, should prevent or control the growth of microbes, prevent or limit biofilm formation, and prevent microbiologically influenced corrosion. In addition, the system should have minimal maintenance requirements, be chemically compatible with all materials in contact with the water, be safe for human consumption, and be suitable to be shared across international spacecraft platforms and mission architectures. Silver ions are a proven broad-spectrum potable water biocide under investigation for future exploration missions. The competing technology for dosing silver ions in future water systems is based on actively dosing the ions via electrolytic production. Several challenges with this approach have prompted additional investigations into alternative dosing techniques. Control-release technology is an attractive option for developing a high-reliability passive silver dosing device. This paper describes the continued development of a nanoparticle/polyurethane (NP/PU) composite foam for the controlled release of silver ions, and is intended to build upon the 2021 International Conference on Environmental Systems (ICES) paper number 116. This paper provides the technical background and performance results (wash testing and ongoing long-term silver ion release testing) from the silver chloride (AgCl) NP/PU composite foams. The ultimate goal of the project is to develop a stable and reliable passive dosing silver ion release device for use in future spacecraft potable water systems.Item Silver Foam: A Novel Approach for Long-Term Passive Dosing of Biocide in Spacecraft Potable Water Systems – Update 2020(2020 International Conference on Environmental Systems, 2020-07-31) Irwin, Tesia; Li, Wenyan; Diaz, Angie; Calle, Luz; Callahan, MichaelA spacecraft water disinfection system suitable for extended length space exploration missions should prevent or control the growth of microbes, prevent or limit biofilm formation, and prevent microbiologically-influenced corrosion. In addition, the system should have minimal maintenance requirements, the effluent should be chemically compatible with all materials in contact with the water, be safe for human consumption, and suitable to be shared across international spacecraft platforms and mission architectures. Silver ions are a proven broad spectrum biocide and the chosen potable water biocide for future exploration missions. The leading technology for actively dosing silver in future water systems is based on electrolytic production. Several challenges remain with this approach which have prompted additional investigations into alternative dosing techniques. Control-release technology is an attractive option for developing a high-reliability passive silver dosing device. This paper describes the development of a nanoparticle (NP)/polyurethane (PU) composite foam for the controlled release of silver ions, and is intended to build upon the 2019 International Conference on Environmental Systems (ICES) paper of the same name. In this paper, the technical background and results from the updated nanoparticle (AgNPs)/PU composite foam synthesis and property testing is provided. The ultimate goal of the project is to develop a stable and reliable passive dosing silver ion release device for use in future spacecraft potable water systems.Item Silver Foam: A Novel Approach for Long-Term Passive Dosing of Biocide in Spacecraft Potable Water Systems � Update 2021(50th International Conference on Environmental Systems, 7/12/2021) Irwin, Tesia; Li, Wenyan; Diaz, Angie; Calle, Luz; Callahan, MichaelA spacecraft water disinfection system suitable for extended length space exploration should prevent or control the growth of microbes, prevent or limit biofilm formation, and prevent microbiologically influenced corrosion. In addition, the system should have minimal maintenance requirements, should be chemically compatible with all materials in contact with the water, be safe for human consumption, and suitable to be shared across international spacecraft platforms and mission architectures. Silver ions are a proven broad-spectrum biocide and the chosen potable water biocide for future exploration missions. The competing technology for dosing silver in future water systems is based on actively dosing silver via electrolytic production. Several challenges remain with this approach that have prompted additional investigations into alternative dosing techniques. Control-release technology is an attractive option for developing a high-reliability passive silver dosing device. This paper describes the development of a nanoparticle (NP)/polyurethane (PU) composite foam for the controlled release of silver ions, and is intended to build upon the 2020 International Conference on Environmental Systems (ICES) paper number 128. In this paper, the technical background and results from the updated silver chloride (AgCl) NP/PU composite foam properties and pre-treatment testing is provided. The ultimate goal of the project is to develop a stable and reliable passive dosing silver ion release device for use in future spacecraft potable water systems.Item An Updated Modeling Study on Nutrient Deprivation as a Biofilm Mitigation Strategy for Long Term Space Missions(50th International Conference on Environmental Systems, 7/12/2021) Diaz, Angie; Li, Wenyan; Irwin, Tesia; Calle, LuzSpacecraft wastewater processing systems are environments where bacterial biofilm growth can cause problems in daily operation. As crewed missions explore beyond the ISS to the Moon and Mars, long periods of system dormancy will be necessary, making biofilm control more challenging. Previously reported preliminary mathematical models of biomass growth, as a function of nutrient availability, were developed to understand the biofilm accumulation in the WPA system under daily operation and potential dormancy conditions. These models were since updated to reflect the effect of oxygen availability, as well as the tank cycling during daily operation. This paper describes the updated models and compares the influence of various nutrient and energy limitations on the biomass product, in order to provide insight on the nutrient deprivation strategy for biofilm mitigation.