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At least 361 records · Page 20

Material Testing in Support of the ISS Electrochemical Disinfection Feasibility Study

The International Space Station Program recognizes the risk of microbial contamination in their potable and non-potable water sources. With the end of the Space Shuttle Program, the ability to send up shock-kits of biocides in the event of an outbreak becomes even more difficult. Currently, the US Segment water system relies primarily on iodine to mitigate contamination concerns. To date, several small cases of contamination have occurred which have been remediated. NASA, however, realizes that having a secondary method of combating a microbial outbreak is a prudent investment. NASA is looking into developing hardware that can generate biocides electrochemically, and potentially deploying that hardware. The specific biocides that the technology could generate include: hydrogen peroxide, oxone, hypochlorite and peracetic acid. In order to use these biocides on deployed water systems, the project must determine that all the materials in the potential application are compatible with the biocides at their anticipated administered concentrations. This paper will detail the materials test portion of the feasibility assessment including the plan for both metals and non-metals along with results to date.

Clements, Anna↗

Development Status of PEM Non-Flow-Through Fuel Cell System Technology for NASA Applications

Today s widespread development of proton-exchange-membrane (PEM) fuel cell technology for commercial users owes its existence to NASA, where fuel cell technology saw its first applications. Beginning with the early Gemini and Apollo programs, and continuing to this day with the Shuttle Orbiter program, fuel cells have been a primary source of electrical power for many NASA missions. This is particularly true for manned missions, where astronauts are able to make use of the by-product of the fuel cell reaction, potable water. But fuel cells also offer advantages for unmanned missions, specifically when power requirements exceed several hundred watts and primary batteries are not a viable alternative. In recent years, NASA s Exploration Technology Development Program (ETDP) funded the development of fuel cell technology for applications that provide both primary power and regenerative fuel cell energy storage for planned Exploration missions that involved a return to the moon. Under this program, the Altair Lunar Lander was a mission requiring fuel cell primary power. There were also various Lunar Surface System applications requiring regenerative fuel cell energy storage, in which a fuel cell and electrolyzer combine to form an energy storage system with hydrogen, oxygen, and water as common reactants. Examples of these systems include habitat modules and large rovers. In FY11, the ETDP has been replaced by the Enabling Technology Development and Demonstration Program (ETDDP), with many of the same technology goals and requirements applied against NASA s revised Exploration portfolio.

Hoberecht, Mark A.↗

Sustainability Base Construction Update

Construction of the new Sustainability Base Collaborative support facility, expected to become the highest performing building in the federal government continues at NASA's Ames Research Center, Moffet Field, Calif. The new building is designed to achieve a platinum rating under the leadership in Energy and Environment Design (LEED) new construction standards for environmentally sustainable construction developed by the U. S. Green Building Council, Washington, D. C. When completed by the end of 2011, the $20.6 million building will feature near zero net energy consumption, use 90 percent less potable water than conventionally build buildings of equivalent size, and will result in reduced building maintenance costs.

Mewhinney, Michael↗

Electrochemical Disinfection Feasibility Assessment Materials Evaluation for the International Space Station

The International Space Station (ISS) Program recognizes the risk of microbial contamination in their potable and non-potable water sources. The end of the Space Shuttle Program limited the ability to send up shock kits of biocides in the event of an outbreak. Currently, the United States Orbital Segment water system relies primarily on iodine to mitigate contamination concerns, which has been successful in remediating the small cases of contamination documented. However, a secondary method of disinfection is a necessary investment for future space flight. Over the past year, NASA Johnson Space Center has investigated the development of electrochemically generated systems for use on the ISS. These systems include: hydrogen peroxide, ozone, sodium hypochlorite, and peracetic acid. To use these biocides on deployed water systems, NASA must understand of the effect these biocides have on current ISS materials prior to proceeding forward with possible on-orbit applications. This paper will discuss the material testing that was conducted to assess the effects of the biocides on current ISS materials.

Rodriquez, Branelle↗

Toward Global Drought Early Warning Capability - Expanding International Cooperation for the Development of a Framework for Monitoring and Forecasting

Drought has had a significant impact on civilization throughout history in terms of reductions in agricultural productivity, potable water supply, and economic activity, and in extreme cases this has led to famine. Every continent has semiarid areas, which are especially vulnerable to drought. The Intergovernmental Panel on Climate Change has noted that average annual river runoff and water availability are projected to decrease by 10 percent-13 percent over some dry and semiarid regions in mid and low latitudes, increasing the frequency, intensity, and duration of drought, along with its associated impacts. The sheer magnitude of the problem demands efforts to reduce vulnerability to drought by moving away from the reactive, crisis management approach of the past toward a more proactive, risk management approach that is centered on reducing vulnerability to drought as much as possible while providing early warning of evolving drought conditions and possible impacts. Many countries, unfortunately, do not have adequate resources to provide early warning, but require outside support to provide the necessary early warning information for risk management. Furthermore, in an interconnected world, the need for information on a global scale is crucial for understanding the prospect of declines in agricultural productivity and associated impacts on food prices, food security, and potential for civil conflict. This paper highlights the recent progress made toward a Global Drought Early Warning Monitoring Framework (GDEWF), an underlying partnership and framework, along with its Global Drought Early Warning System (GDEWS), which is its interoperable information system, and the organizations that have begun working together to make it a reality. The GDEWF aims to improve existing regional and national drought monitoring and forecasting capabilities by adding a global component, facilitating continental monitoring and forecasting (where lacking), and improving these tools at various scales, thereby increasing the capacity of national and regional institutions that lack drought early warning systems or complementing existing ones. A further goal is to improve coordination of information delivery for drought-related activities and relief efforts across the world. This is especially relevant for regions and nations with low capacity for drought early warning. To do this requires a global partnership that leverages the resources necessary and develops capabilities at the global level, such as global drought forecasting combined with early warning tools, global real-time monitoring, and harmonized methods to identify critical areas vulnerable to drought. Although the path to a fully functional GDEWS is challenging, multiple partners and organizations within the drought, forecasting, agricultural, and water-cycle communities are committed to working toward its success.

GDEWS↗

The Utilization of Urine Processing for the Advancement of Life Support Technologies

The success of long-duration missions will depend on resource recovery and the self-sustainability of life support technologies. Current technologies used on the International Space Station (ISS) utilize chemical and mechanical processes, such as filtration, to recover potable water from urine produced by crewmembers. Such technologies have significantly reduced the need for water resupply through closed-loop resource recovery and recycling. Harvesting the important components of urine requires selectivity, whether through the use of membranes or other physical barriers, or by chemical or biological processes. Given the chemical composition of urine, the downstream benefits of urine processing for resource recovery will be critical for many aspects of life support, such as food production and the synthesis of biofuels. This paper discusses the beneficial components of urine and their potential applications, and the challenges associated with using urine for nutrient recycling for space application.

Resource Recovery↗

Life Support and Environmental Monitoring International System Maturation Team Considerations.

Human exploration of the solar system is an ambitious goal. Future human missions to Mars or other planets will require the cooperation of many nations to be feasible. Exploration goals and concepts have been gathered by the International Space Exploration Coordination Group (ISECG) at a very high level, representing the overall goals and strategies of each participating space agency. The Global Exploration Roadmap published by ISECG states that international partnerships are part of what drives the the mission scenarios. It states "Collaborations will be established at all levels (missions, capabilities, technologies), with various levels of interdependency among the partners." To make missions with interdependency successful, technologists and system experts need to share information early, before agencies have made concrete plans and binding agreements. This paper provides an overview of possible ways of integrating NASA, ESA, and JAXA work into a conceptual roadmap of life support and environmental monitoring capabilities for future exploration missions. Agencies may have immediate plans as well as long term goals or new ideas that are not part of official policy. But relationships between plans and capabilities may influence the strategies for the best ways to achieve partner goals. Without commitments and an organized program like the International Space Station, requirements for future missions are unclear. Experience from ISS has shown that standards and an early understanding of requirements are an important part of international partnerships. Attempting to integrate systems that were not designed together can create many problems. Several areas have been identified that could be important to discuss and understand early: units of measure, cabin CO2 levels, and the definition and description of fluids like high purity oxygen, potable water and residual biocide, and crew urine and urine pretreat. Each of the partners is exploring different kinds of technologies. Different specific parameters may important to define or explore possible ranges depending on the system concepts. Early coordination between technology developers can create new possibilities for collaboration, and provide input to determine what combined options may provide the best overall system architecture.

Anderson, Molly↗

Life Support and Environmental Monitoring International System Maturation Team Considerations

Human exploration of the solar system is an ambitious goal. Future human missions to Mars or other planets will require the cooperation of many nations to be feasible. Exploration goals and concepts have been gathered by the International Space Exploration Coordination Group (ISECG) at a very high level, representing the overall goals and strategies of each participating space agency. The Global Exploration Roadmap published by ISECG states that international partnerships are part of what drives the mission scenarios. It states "Collaborations will be established at all levels (missions, capabilities, technologies), with various levels of interdependency among the partners." To make missions with interdependency successful, technologists and system experts need to share information early, before agencies have made concrete plans and binding agreements. This paper provides an overview of possible ways of integrating NASA, ESA, and JAXA work into a conceptual roadmap of life support and environmental monitoring capabilities for future exploration missions. Agencies may have immediate plans as well as long term goals or new ideas that are not part of official policy. But relationships between plans and capabilities may influence the strategies for the best ways to achieve partner goals. Without commitments and an organized program like the International Space Station, requirements for future missions are unclear. Experience from ISS has shown that standards and an early understanding of requirements are an important part of international partnerships. Attempting to integrate systems that were not designed together can create many problems. Several areas have been identified that could be important to discuss and understand early: units of measure, cabin CO2 levels, and the definition and description of fluids like high purity oxygen, potable water and residual biocide, and crew urine and urine pretreat. Each of the partners is exploring different kinds of technologies. Different specific parameters may important to define or explore possible ranges depending on the system concepts. Early coordination between technology developers can create new possibilities for collaboration, and provide input to determine what combined options may provide the best overall system architecture.

Anderson, Molly↗

Microbial Monitoring and the Risk of Infectious Disease Aboard the International Space Station

The International Space Station (ISS) is a semi-closed habitat in low Earth orbit with environmental conditions provided by an advanced life support system that controls temperature and recycles air and most of the potable water. The crew's activities, such as eating, sleeping, hygiene, and laboratory research, are performed in relatively close proximity. Research in the laboratory includes a myriad of experiments, including those with rodents, plants, and pathogenic microorganisms. Despite these conditions, in-flight monitoring of ISS indicates that the microbial diversity is similar to homes on earth. Accordingly, the crew is generally very healthy, however infectious disease does occur and potential routes of infection by obligate and opportunistic pathogens cannot be completely prevented. Determining the extent of this risk is further complicated, as microorganisms can alter their characteristics in response to spaceflight culture, as exemplified by the increase in virulence of the enteric pathogen Salmonella enterica Typhimurium during spaceflight compared to otherwise identical cultures grown on Earth. Taken together, these factors suggest a need for continued microbiological monitoring and research to understand and mitigate the risk of infectious disease during long duration missions.

Ott, C. Mark↗

Spaceflight Microbiology

Microbiological Areas of Concern: Astronaut Health; Vehicle integrity; Life support and other systems failure -Biofilm formation/biofouling -Bio-corrosion and biodegradation -Trash and human waste containment -Risk of condensation -Astronaut hygiene areas; Spaceflight foods -Impact of “pick and eat” foods on the environment -Impact of the environment on “pick and eat” foods -Rinsing food with potable water is impractical; Planetary protection -How do we track what we are leaving versus what we are finding in our search for life on other planets?

Ott, C. Mark↗

Mitigation of Silver Ion Loss from Solution by Polymer Coating of Metal Surfaces

Spacecraft potable water systems require a biocidal agent that effectively provides both immediate and residual disinfection over long periods of time. Ionic silver (Ag+) is a leading candidate for this application, but suffers from rapid concentration loss due interactions with the metal storage containers and tubing. In order to maintain biocidal efficacy in systems with long periods of dormancy and to reduce the required rate of Ag+ injection, it is necessary to develop alternative materials and coatings for certified metal alloys that significantly reduce the Ag+ loss. In this work, we investigate the performance of two unusual polymers, Teflon AF 2400 and parylene-AF4, as barrier coatings under immersion in 400 ppb Ag+. We show that 25 m-thick parylene-AF4 is a promising coating with Ag+ losses similar to PTFE. Key challenges with this material include maintenance of adhesion under long-term immersion and control of deposition during the internal coating of high-aspect ratio tubing. Solutions to these problems may including surface structuring of substrates for mechanical anchoring or an alternative parylene-C chemistry (with more stable adhesion), and dynamic spatio-temporal control of substrate temperature, respectively.

water↗

Early Results from a Broad Compatibility Study of Various Materials with Ionic Silver Biocide

Ionic silver is baselined for microbial control in spacecraft potable water systems forfuture exploration missions, but materials compatibility analysis is required to evaluate thepassive depletion of ionic silver concentration onto wetted material surfaces over time.Various articles concerning such testing have been published that examine interactions withwater containing ionic silver biocide, but most tests have focused on only a couple ofmaterials each and comparing results of different evaluations to one another has provedchallenging.This paper reports the first results from static exposure testing of a large arrayof material coupons to a 400 parts per billion (ppb) aqueous silver fluoride (AgF) solution,using a surface to volume ratio of approximately 2 cm-1. The test is designed in two mainstages. Stage 1 is a one-week screening to evaluate silver uptake. Materials that performmodestly to well after that week are promoted to Stage 2, which is a longer test with periodicsampling to examine the silver uptake rates over time; these samples are evaluated for otherwater quality parameters in addition to the remaining silver concentration. In a tangentialinvestigation, select materials that take up some silver in Stage 1 may be “aged” by repeatingthe Stage 1 test to determine whether repeated exposure reduces silver uptake rate, andsuccessfully aged materials may then continue to Stage 2 testing. The materials under testinclude metallic and polymeric materials with various surface finishes, treatments, andcoatings, as well as select other materials historically used in spacecraft water systems. Thistest began in August 2019, and thus only includes early results; future follow-on papers willinclude additional results as the test progresses. The ultimate goal builds a broad, easilycomparable data set that can be used to guide material selections for silver biocide-compatible spacecraft water system design.

Silver Biocide↗

Broad Compatibility Study of Polymeric Materials with Ionic Silver Biocide, Part I

NASA is considering ionic silver as a residual biocide for use in potable water systems being planned for future exploration spacecraft. Compatibility of the biocide with the system’s wetted-materials of construction remains a challenge. Due to the relatively inert nature of plastics, their use in varied water system applications may offer unique opportunities to address many biocide compatibility issues. A 2020 ICES paper described a “Stage 1” assessment of several polymeric materials, in which coupons having a 2 cm 1 surface to volume ratio were exposed to solutions of 400 parts per billion (ppb) aqueous silver fluoride (AgF) for one week. In this current paper, additional Stage 1 test results are presented for select epoxies and lubricants applied on silver-inert substrates. The coupon exposure studies were also expanded to a duration of 5 weeks for the “well-behaved” Stage 1 plastics previously reported: those exhibiting silver losses above 10% and less than 50%. For this type of Stage 2 testing, silver biocide solution samples are taken from three separate (and not previously-sampled) coupon containers after 3 days, and 2, 3, 4, and 5 weeks of exposure. "Very well-behaved" Stage 1 plastics will be tested in the same manner over one year, with longer sample intervals; early-period results are included here. In addition, for select materials, the coupons were “aged” by refilling test containers with fresh AgF and observing the respective silver uptake over similar Stage 2 test durations. For all test series, Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and ion-selective electrode (ISE) analyses were used to determine total and ionic silver (Ag+) concentrations, respectively. Additional sample analyses for Stage 2 tests includes total organic carbon (TOC), pH, conductivity, and oxidation-reduction potential (ORP). Ultimately, these early compatibility studies will be used to guide future material selections for developing silver biocide-compatible spacecraft water systems.

Silver Biocide↗

Assessment of Biocide Impacts on Life Support (LS) and Extravehicular Activity (EVA) Architectures

The Project Manager for the Human Exploration and Operations Mission Directorate’s Advanced Exploration Systems Life Support Systems (LSS) project, requested a NASA Engineering and Safety Center (NESC) assessment to evaluate potable water system biocide options impacting Gateway, Human Lander Systems, Foundation Surface Habitat, and Exploration Command Module missions. The assessment focused on identifying feasible biocide options, evaluating the impacts of their implementation on crew health, extravehicular activity hardware, and LSS hardware, and conducting a trade on architecture options. This report contains the outcome of the NESC assessment.

Extravehicular Activity; Life Support; NASA Engine↗

Mitigation of Silver Ion Loss from Solution by Polymer Coating of Metal Surfaces, Part II

“Spacecraft potable water systems require a biocidal agent that effectively provides both immediate and residual disinfection over long periods of time. Ionic silver (Ag+) is a leading candidate for this application, but suffers from rapid concentration loss due to interactions with the metal storage containers and tubing. In order to maintain biocidal efficacy in systems with long periods of dormancy and to reduce the required rate of Ag+ injection, it is necessary to develop alternative materials and coatings for certified metal alloys that significantly reduce the Ag+loss.”1In this work, we continue our investigation of vapor-deposited parylene (AF4, and now C) polymers as conformal barrier coatings under long-term (ca. 1-year) immersion in ca. 400 ppb Ag+. The performanceof internal coatings in tubing/two-ferrule fitting systems is characterized. We report successful “aging” and high concentration Ag+pretreatment of parylene coatings for quantitative reduction of Ag+loss rates. In addition, we observe long-term blister-free adhesion of mechanically anchored parylene-AF4 on nano-structured Ti-6Al-4V alloy and chemically bonded parylene-C on 316L stainless steel. Finally, we report preliminary experiments with mechanical and chemical anchoring of laboratory-deposited parylene-C on 316L.

Silver↗

Monitoring of Ionic Silver Biocide with Capacitively-Coupled Contactless Conductivity Detection (C4D)

Monitoring of biocide dosing in spacecraft potable water systems is desirable to ensure dosing system operation and resultant microbial control. Electrolytic conductivity is linearly related to the concentration ionic silver (Ag+, the baseline biocide for future NASA missions) chemically dosed into highly purified water, and could serve as a proxy measurement. Traditional conductivity cells rely on immersed metal or graphite electrodes, which may potentially be subject to significant current-induced or auto-galvanic deposition of Ag+. Furthermore, oxide fouling may potentially induce measurement errors. Capacitively-coupled contactless conductivity detection (C4D) is a promising alternative. C4D uses electrodes placed outside an inert, non-conductive flow path, potentially mitigating such problems. We identified and purchased a commercial C4D system with claimed performance (conductivity range: 20 nS/cm to 4 µS/cm) appropriate for this application. We characterized the instrument’s performance with conductivity standards and Ag+ solutions. We began investigations considering practical and long-term detector operation, including potential current-induced deposition of conductive deposits at the tubing wall. In addition, we designed a side-stream flow system to provide liquid flow through the narrow tubing (1/16” outer diameter) required by the detector and characterized the performance of the combined C4D detector/flow system. Finally, we completed theoretical modeling of expected conductivity change with multiple dosing techniques and water chemistries.

Lance Dean Delzeit↗

DirectINJECT: Dosing Systems for Concentrated Liquid Biocides

Reliable and mass-efficient techniques for biocide dosing are necessary to enable residual microbial control in spacecraft potable water systems. DirectINJECT is an approach to provide residual microbial control by injection of concentrated aqueous biocide solution (e.g., highly soluble silver salt), and associated dosing systems technology developments. This would allow for well-controlled liquid biocide injection that requires low consumable mass and is insensitive to the chemistry of the target water. With a 40 g Ag+/l solution, required dosing rates would be ~1 μl/minute during water processing (for a system similar to the ISS WPA), requiring only approximately 20 ml/crew-year of concentrate. We identified and characterized the performance of three dosing systems: pressure-driven flow through a robust micro-capillary tube, a miniature peristaltic pump, and a multi-piston pump with integrated valving. We began to address several potential system reliability concerns including prevention or segregation of gas bubbles in the concentrate reservoirs as well as long-term materials compatibility and mechanical life.

Lance Dean Delzeit↗

DirectINJECT: Dosing Systems for Concentrated Liquid Biocides

Reliable and mass-efficient techniques for biocide dosing are necessary to enable residual microbial control in spacecraft potable water systems. DirectINJECT is an approach to provide ultra-low flow rate injection of stable aqueous biocide concentrate solution (e.g., highly soluble silver salt). This method has the benefit of low consumable mass and is insensitive to the chemistry of the target water. With a 40 g Ag+/liter solution, required dosing rates would be ~1 μl/minute during water processing (for a system similar to the ISS WPA), requiring only approximately 20 ml/crew-year of concentrate. The performance of three dosing systems were identified and characterized: pressure-driven flow through a robust micro-capillary tube with a solenoid valve shut-off, a miniature peristaltic pump, and a multi-piston pump with integrated valving. Several potential system reliability concerns are addressed including prevention or segregation of gas bubbles in the concentrate reservoirs as well as long-term materials compatibility and mechanical life.

silver↗