Browsing by Author "Hummerick, Mary"

Now showing 1 - 14 of 14

An Assessment of the Water Extraction Capabilities of the Heat Melt Compactor
(44th International Conference on Environmental Systems, 2014-07-13) Alba, Richard; Harris, Linden; Wignarajah, Kanapathipillai; Fisher, John; Hummerick, Mary; Pace, Gregory; Delzeit, Lance; Larson, Brian
The Heat Melt Compactor (HMC), a waste management technology developed at the NASA Ames Research Center, was designed to process waste generated aboard spacecraft. The device compacts, encapsulates and sterilizes the waste in preparation for onboard storage. In addition, the unit removes and recovers water, which is ultimately recycled1, rendering the encapsulated waste inhospitable to microbial contaminants. Initial studies indicate that the HMC is capable of removing and capturing 90 to 98% of the water contained in the process waste sample.2 The nineteen experiments conducted at ARC described in this paper attempt to refine, quantify and define the limitations of the Heat Melt Compactor's dewatering and water collection capabilities. The amount of water in the initial waste sample was measured and found to be 19.04% by weight for batches made at ARC and 20.45% for those made at KSC. This was less than the percentage predicted from the standard waste model. The amount of water recovered and collected varied from 12.9 to 98.4% of initial water contained in the waste. For the six tiles tested, the amount of water remaining in the tiles after processing ranged from 6.97 to 37.67%. The water activity for five of these tiles averaged 0.472; all of these issues play a significant role in the survival and propagation of microorganisms. Water activity values below 0.6 inhibit microbial growth. Significant correlation was found to exist between Percent Water Recovery, Percent Expected Water Encapsulated in Tile and Water Activity, the latter two of which are inversely proportional to water recovered. Percent Water Recovery, since it is easily computed, can be used to predict the other two values.
Biofilm Resistant Coatings for Space Applications
(48th International Conference on Environmental Systems, 2018-07-08) Li, Wenyan; Hummerick, Mary; Khodadad, Christina; Buhrow, Jerry; Spencer, Lashelle; Coutts, Janelle; Roberson, Luke; Tuteja, Anish; Mehta, Geeta; Boban, Mathew; Barden, Michael
Bacterial biofilms are an important and often problematic aspect of life on earth and in space. Microbial contamination onboard the International Space Station (ISS) continues to pose mission risks, both to crew health and hardware reliability. In order to optimize the design of the future space exploration vehicle for long term missions, new technologies are needed to control the habitat’s microbial environment over multiple years. Among the emerging technologies for combating biofilm, new surface coatings show promise for preventing biofilm formation. This approach aims to interrupt the critical initial step of biofilm formation (cell attachment) through surface modification. When successfully developed, biofilm resistant coatings can eliminate/reduce the need for disinfectants, and avoid the development of “superbugs,” thus offering distinctive advantages for biofilm prevention during long term missions. Initial results at KSC showed that omniphobic coatings are promising candidates as biofilm resistant materials. Parabolic flight experiments also verified their physical properties under microgravity.
Dwarf Tomato and Pepper Cultivars for Space Crops
(49th International Conference on Environmental Systems, 2019-07-07) Spencer, Lashelle; Hummerick, Mary; Stutte, Gary; Sirmons, Takiya; Graham, Thomas; Massa, Gioia; Wheeler, Raymond
Crops for space life support systems and in particular, early supplemental food production systems must be able to fit into the confined volume of space craft or space habitats. For example, spaceflight plant chambers such as Svet, Lada, Astroculture, BPS, and Veggie provided approximately 15-40 cm of growing height for plant shoots. Six cultivars each of tomato and pepper were selected for initial study based on their advertised dwarf growth and high yields. Plants were grown in 10-cm pots with solid potting medium and controlled-release fertilizer to simulate the rooting constraints that might be faced in space environments. Lighting was provided by fluorescent lamps (~300 umol m-2 s-1) and a 16 h light / 8 h dark photoperiod. Cultivars were then down selected to three each for pepper (cvs. Red Skin, Pompeii, and Fruit Basket) and tomato (cvs. Red Robin, Mohamed, and Sweet n’ Neat). In all cases (pepper and tomato), the plants grew to an approximate height of 20 cm and produced between 200 and 300 g fruit fresh mass per plant. In previous hydroponic studies with unrestricted root growth, Fruit Basket pepper and Red Robin tomato produced much larger plants with taller shoots. The findings suggest that high value, nutritious crops like tomato and pepper could be grown within small volumes of space habitats, but horticultural issues, such as rooting volume could be important in controlling plant size.
Evaluation of Long-Term Microbial Regrowth in Slosh Water Tanks from the International Space Station
(2023 International Conference on Environmental Systems, 2023-07-16) Roberson, Luke; Fischer, Jason; Saetta, Daniella; Franco, Carolina; Kodadad, Christina; Hummerick, Mary; Spern, Cory; Yeh, Daniel; Pickett, Melanie
The NASA Launch Services Program (LSP) maintained the SPHERES-Slosh experiment aboard the International Space Station (ISS) between 2013 and 2019. The purpose of the Slosh experiment was to examine how liquids move inside fuel tanks in a microgravity environment. These tanks were similar to water storage tanks planned for use aboard future space systems, where large dormant periods between crew-use will provide similar conditions for biological growth or chemical leaching. The water within the SLOSH tanks remained undisturbed for over five years after testing concluded, providing a unique sample for stored water under microgravity conditions without prior protocols for microbial control such as sterilization or addition of biocides. The Slosh storage tanks were returned to Kennedy Space Center (KSC) aboard SpaceX CRS-18 mission in November 2019. Upon return of the tanks, the water within each tank was analyzed to determine how the water chemistry and biology changed during its tenure in microgravity. The data obtained and described within this publication provided a basis and reasoning for planning water storage and purification treatment methods aboard ISS, Gateway, and future space habitats. Results demonstrated that low microbial concentrations were present within the water, as expected since no biocide treatment was employed, yet no extensive biofilm formation was observed after 5 years even in the presence of microbial food sources such as the polycarbonate structure and food color additives. This experimentation demonstrates that future biofilm studies should be performed on this type of experimental setup with proper controls aboard ISS to examine microbial regrowth to improve microbial control within space water systems.
Evaluation of Low-Pressure Cold Plasma for Disinfection of ISS Grown Produce and Metallic Instrumentation
(47th International Conference on Environmental Systems, 2017-07-16) Hintze, Paul; Franco, Carolina; Hummerick, Mary; Maloney, Phillip; Spencer, Lashelle
Cold plasma (CP) cleaning is a dry, non-thermal process, which can provide broad-spectrum antimicrobial activity yet reportedly causes little to no damage to the object being sanitized. Since cold plasma uses no liquids, it has the distinct advantage when used in microgravity of not having to separate liquids from the item being cleaned. This paper will present results on an effort to use low pressure CP to disinfect or sterilize materials for in space applications. Exposure times from 0 to 60 minutes and pressures ranging from 0.10 to 1.0 mbar were used to optimize plasma parameters. Tests were done on produce and metal coupons to simulate medical equipment. Escherichia coli was used as the challenge organism on produce and Bacillus pumilus SAFR-32 was used on metal surfaces. Produce testing was not successful, with unacceptable kill rates and the produce being negatively impacted by exposure to the plasma. The plasma caused a 5 log reduction in the number of viable bacteria on metal coupon tests, which placed the number of viable bacteria below the detection limit. This is a very promising result showing that sterilization of medical equipment with cold plasma is feasible. Scanning Electron Microscope images were taken before and after exposure. The images after plasma exposure show that the bacteria spores have been physically affected, as their size has gotten smaller and their appearance has changed.
Hollow Fiber Membrane Bioreactor Systems for Wastewater Processing: Effects of Environmental Stresses Including Dormancy Cycling and Antibiotic Dosing
(46th International Conference on Environmental Systems, 2016-07-10) Coutts, Janelle; Hummerick, Mary; Lunn, Griffin M.; Larson, Brian; Spencer, Lashelle; Kosiba, Michael; Khodadad, Christina; Catechis, John
Hollow fiber membrane bioreactors (HFMBs) have been studied for a number of years as an alternate approach for treating wastewater streams during space exploration. While the technology provides a promising pre-treatment for lowering organic carbon and nitrogen content without the need for harsh stabilization chemicals, several challenges must be addressed before adoption of the technology in future missions. One challenge is the transportation of bioreactors containing intact, active biofilms as a means for rapid start-up on the International Space Station or beyond. Similarly, there could be a need for placing these biological systems into a dormant state for extended periods when the system is not in use, along with the ability for rapid restart. Previous studies indicated that there was little influence of storage condition (4 or 25ºC, with or without bulk fluid) on recovery of bioreactors with immature biofilms (48 days old), but that an extensive recovery time was required (20+ days). Bioreactors with fully established biofilms (13 months) were able to recover from a 7-month dormancy within 4 days (~1 residence). Further dormancy and recovery testing is presented here that examines the role of biofilm age on recovery requirements, repeated dormancy cycle capabilities, and effects of long-duration dormancy cycles (8-9 months) on HFMB systems. Another challenge that must be addressed is the possibility of antibiotics entering the wastewater stream. Currently, for most laboratory tests of biological water processors, donors providing urine may not contribute to the study when taking antibiotics because the effects on the system are yet uncharacterized. A simulated urinary tract infection event, where an opportunistic, pathogenic organism, E. coli, was introduced to the HFMBs followed by dosing with an antibiotic, ciprofloxacin, was completed to study the effect of the antibiotic on reactor performance and to also examine the development of antibiotic-resistant communities within the system.
Investigation into Simulated Microgravity Techniques Used to Study Biofilm Growth
(51st International Conference on Environmental Systems, 2022-07-10) Diaz, Angie; Li, Wenyan; Irwin, Tesia; O'Rourke, Aubrie; Calle, Luz; Hummerick, Mary; Khodadad, Christina; Gleeson, Jonathan; Callahan, Michael
Bacterial 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.
Microbial Characterization of Heat Melt Compaction for Treatment of Space Generated Solid Wastes
(51st International Conference on Environmental Systems, 2022-07-10) Hummerick, Mary; Fisher, Jason; Wheeler, Raymond; Richardson, Tra-My Justine; Ewert, Michael; Lee, Jeffrey; Koss, Lawrence
One treatment process in development for solid waste management in space has been the Trash Compaction Processing System (TCPS). Heat Melt Compaction (HMC) technology, a TCPS liked hardware, which is operated to reduce trash volume and safen the trash by compaction and heat, while simultaneously removing water. Human space mission wastes typically contain large percentages contaminated wet solid waste. The HMC is being developed to be a multi-function means of water recovery, volume reduction, and the safening of contaminant-rich trash with the potential for waste stabilization and/or sterilization. To determine the efficacy of the HMC treatment to kill microorganisms in solid waste and remain biologically stable, testing was done on three tiles produced by HMC Gen 2 at Ames Research Center. Samples were shipped to Kennedy Space Center to test for microbial viability after compaction, determine the bio-stability of the HMC disks during storage (43 days), and assess potential airborne contaminate microbial growth on surfaces. In addition to the products of waste processing, there is a concern that the crew might come into contact with hardware surfaces that have been contaminated by microorganisms during waste processing. The extent of microbial surface contamination of waste processing hardware was determined by surface sample swabbing and analysis for total bacterial and yeast counts and cultivable counts of aerobic and anaerobic bacteria, spore-forming bacteria, and fungi. Results indicate that trash processing increased bacterial counts on the surfaces of the compacter. All but one biological indicator spore strip imbedded in the tiles were negative for growth after incubation for five days indicating effective sterilization through the heat melt compaction process. Analysis of core samples and surface growth of tiles inoculated with Aspergillus niger fungal spores incubated at three different humidities indicate that HMC created tiles do not support the proliferation of bacterial and fungal growth.
Mitigation of Biofouling in Plant Watering Systems Using AgXX, a Novel Surface Treatment
(2023 International Conference on Environmental Systems, 2023-07-16) Irwin, Tesia; Li, Wenyan; Diaz, Angie; Hummerick, Mary
The development of plant growth systems with high yield and low maintenance for food production is a key focus area for NASA. One of the remaining technical challenges is keeping the plant watering systems clean without affecting plant growth, requiring consumables, or demanding crew time. Plant watering systems, such as the one onboard ISS, provide a nutrient rich environment for biofilm formation. Frequent maintenance is necessary to prevent biofouling, which currently requires crew time and mechanical means of cleaning. Better solutions are needed. The current ISS practices for biofilm mitigation in the water recovery and distribution system include the use of biocides (silver ion or iodine) along with regular maintenance (e.g. flushing, filter replacement). These biocide-based strategies could be problematic for plant watering systems, such as Ohalo, Exploration Garden, and APH, due to incompatibilities of the biocides with plants. We propose the application of AgXX, a novel antifouling surface treatment that meets the above requirements. This paper will report on an initial study that was completed to determine whether AgXX would be effective in a plant nutrient solution, and whether or not it would negatively impact plant growth in an aquaponics-type system.
New Frontiers in Food Production Beyond LEG
(49th International Conference on Environmental Systems, 2019-07-07) Monje, Oscar; Dreschel, Tom; Nugent, Matthew; Hummerick, Mary; Spencer, Lashelle; Romeyn, Matthew; Massa, Gioia; Wheeler, Raymond; Fritsche, Ralph
New technologies will be needed as mankind moves towards exploration of cislunar space, the Moon and Mars. Although many advances in our understanding of the effects of spaceflight on plant growth have been achieved in the last 40 years, spaceflight plant growth systems have been primarily designed to support space biology experiments where the mission ended after the completion of a series of experiments. Recently, the need for a sustainable and robust food system for future missions beyond LEO has identified gaps in current technologies for food production. The goal is to develop safe and sustainable food production systems with reduced resupply mass and crew time than current systems. New soilless water and nutrient delivery systems are needed to avoid constant resupply of bulky single-use porous media. Autonomous plant health and food safety monitoring systems are needed for to ensure that the food produced is suitable for supplementing crew diets with fresh and nutritious salad crops. New plant species and cultivars with improved contents of antioxidants, vitamins, and minerals when grown elevated CO2 concentrations found in spacecraft. These improvements in food production technologies will enable the design of more robust and sustainable life support systems for manned exploration missions beyond Low Earth Orbit.
Recovery of Nutrients from Inedible Biomass of Tomato and Pepper to Recycle Fertilizer
(47th International Conference on Environmental Systems, 2017-07-16) Lunn, Griffin; Stutte, Gary; Spencer, Lashelle; Hummerick, Mary; Wong, Les; Wheeler, Raymond
Plants can be used as a source food, oxygen, and help remove carbon dioxide for human life support in space. But to grow these plants will require sufficient nutrients (fertilizer). This fertilizer can be stowed and resupplied, but this imposes a mass cost to the mission. Depending on the crop, a large portion of the biomass will be inedible. This inedible biomass contains various nutrients that can be recycled for subsequent crops, hence reducing the need for imported fertilizer. Previous studies demonstrated that continuously stirred tank bioreactors and composters can be used to retrieve many of these nutrients. This can provide a liquid effluent that is easily used in hydroponic systems. We explored various approaches to achieve more complete recovery of nutrients from inedible biomass, and focused our testing on pepper and tomato leaves and stems. Approaches included water leaching, acid treatment, microbial degradation, photocatalytic oxidation, thermal methods, and various combinations of these. Acid (0.1 M or 1.0 M HCl) pretreatment with contact times as low as 10 minutes proved effective in combination with many approaches. To date, these treatments have not been able to recover more than 70% of some macronutrients regardless of combination of treatments. This recalcitrant inorganic fraction needs additional study to explore cost effective approaches for closing the mass loop for crop growth systems.
Silver Foam: A Novel Approach for Long-Term Passive Dosing of Biocide in Spacecraft Potable Water Systems – Update 2023
(2023 International Conference on Environmental Systems, 2023-07-16) Irwin, Tesia; Diaz, Angie; Gooden, Jennifer; Hummerick, Mary; Li, Wenyan; Azim, Nilab; Essumang, Deborah; Callahan, Michael
A spacecraft water disinfection system that 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. Ionic silver is 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. Controlled-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 2022 International Conference on Environmental Systems (ICES) paper number 97. This paper provides the technical background and performance test results of ongoing long-term silver ion release testing, microbial check valve (MCV) function, and disinfection function during system dormancy 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.
Silver Foam: A Novel Approach for Long-Term Passive Dosing of Biocide in Spacecraft Potable Water Systems – Update 2024
(2024 International Conference on Environmental Systems, 2024-07-21) Irwin, Tesia D.; Diaz, Angie; Gooden, Jennifer; Atanowski, Rachael; Hummerick, Mary; Li, Wenyan; Azim, Nilab; Essumang, Deborah; Callahan, Michael R.
A 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 2023 International Conference on Environmental Systems (ICES) paper number 251. This paper provides the technical background and performance results for the product variability testing and microbial check valve (MCV) testing of the silver chloride (AgCl) NP/PU composite foams, referred to as AgFoams. 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.
The Microbiology of Microgreens Grown in Controlled Environment Chambers under ISS Conditions
(51st International Conference on Environmental Systems, 2022-07-10) Hummerick, Mary; Curry, Aaron; Gooden, Jennifer; Spern, Cory; Spencer, Lashelle; Romeyn, Matthew; Fischer, Jason
Microgreens have been identified as a new type of pick-and-eat salad crop that can be utilized in space crop production systems. The majority of traditionally grown leafy green crops can be grown as microgreens, in addition to crops such as legumes, sunflower, buckwheat, most herbs, and corn, presenting hundreds of microgreen crop options. Notably, microgreens are nutrient dense, high in beneficial compounds like antioxidants, Vitamins C and K, and exhibit a variety of desirable flavors and textures. The short growth cycles (7-14 days), low water requirements and volume optimization potential make them a viable option for sustainable production of nutritious and flavorful crops in space. The crop production team at Kennedy Space Center is investigating the food safety aspects of microgreens grown under spaceflight relevant conditions for crew consumption. Microbiological analysis and screening for potential foodborne pathogens was performed on over 20 varieties of microgreens that have demonstrated positive horticultural attributes. Additionally, a comparison of microgreens grown hydroponically under ISS environmental conditions and similar varieties from local markets was completed to collect baseline data on the microbial load on microgreens. In an effort to improve microgreen quality, strategies to reduce the microbial load were tested, including bulk seed sanitization, harvest age, exposure to high blue light, and post-harvest chemical disinfection. The efficacy of a citric acid-based produce wash currently used for ISS grown produce and 1% H2O2 were investigated at different exposure times for reduction in bacterial and fungal counts on a variety of microgreens. Limited log reduction was achieved depending on exposure time. Our testing also demonstrated that seed sanitization impacted microbial load on microgreens and systems.