Browsing by Author "Mungin, Rihana"
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Item Mitigation of Micro-Droplet Ejections During Open Cabin Unit Operations Aboard ISS(49th International Conference on Environmental Systems, 2019-07-07) Turner, Caleb; Weislogel, Mark; Goodman, Jesse; Mohler, Sam; Mungin, Rihana; Ungar, Eugene; Buchli, JenniferThe rupture and break-up of thin films, droplets, bubbles, and rivulets can produce tiny satellite droplet ejections. For example, when nearly any object is withdrawn from a liquid bath, the formation of an ever-thinning columnar rivulet eventually ruptures, ejecting a variety of satellite droplets that are often too small and too fast to observe by eye. In terrestrial environments such events are often of little concern due to the fact that gravity rapidly returns such drops to the liquid surface from which they came. This of course is not the case in low-g environments where during simple activities such as pipetting these satellite drops travel away from the liquid only to impact the surrounding surfaces leading to possible contamination of the working environment. In this work we demonstrate the variety of micro-droplet ejections formed during simple wet lab unit operations such as pipetting and how in the low-gravity environment such dynamics depend on system geometry, wettability, fluid properties, and withdraw rate. A large drop tower dataset is collected in support of regime maps organized by the appropriate dimensionless groups. The results can be exploited to guide mitigation strategies for high volume wet lab operations aboard spacecraft; i.e., manifold pipetting, sequencing, 3-D printing, and more.Item Omni-gravity Hydroponics for Space Exploration(49th International Conference on Environmental Systems, 2019-07-07) Mungin, Rihana; Weislogel, Mark; Hatch, Tyler; McQuillen, JohnAs part of the NASA Plant Water Management technology demonstration experiments, a capillary fluidics hydroponic system that can function in a variety of gravity environments has been developed and tested for crop production in space. A passive liquid delivery method is employed that drastically reduces the number of contaminable moving parts providing a high reliability solution requiring minimal resources for operation. The terrestrial, lunar, and Martian environments are managed in a ‘gravity-dominated mode,’ while the low-gravity transit and orbit environments are managed in a ‘capillary fluidics mode,’ where the role of gravity is replaced by the equally passive effects of surface tension, conduit shape, and wettability. The unique considerations for priming, germination, aeration, nutrient supply, root accommodation, layout, crew interaction, etc. are highlighted. Design guides for system function are provided along with high Technology Readiness Level demonstrations of the system during terrestrial and drop tower tests. Long duration tests are planned on short schedule aboard the International Space Station in 2019.Item Plant Water Management in Microgravity(2020 International Conference on Environmental Systems, 2020-07-31) Hatch, Tyler; Weislogel, Mark; Mungin, Rihana; Hernandez, MariaThe NASA Plant Water Management (PWM) technology demonstrations aboard ISS apply recent advances in microgravity capillary fluidics research towards the mundane yet problematic challenges of simply watering plants in space. Plant growth in a low-g environment is often hampered by inadequate aeration and over-saturation of the root zone. The present effort aims to exploit the passive capillary forces of poorly wetting liquids (i.e., contaminated water) within unique system geometries that effectively replace the role of gravity in providing sufficient aeration and hydration for simulated plants. Several ISS demonstrations are currently on orbit for experiments in late 2019 through 2020, including soil and hydroponic models in single and parallel channel networks. Supportive terrestrial and low-g drop tower tests are conducted to aid in experiment design via scale- and full-scale demonstrations. The test demonstrate proof-of-concept, limits of operation, system stability, and more. Applications are discussed in relation to plant growth facilities for both near-term microgravity plant science research and long duration human exploration missions.Item The Plant Water Management Experiments on ISS: Soil(51st International Conference on Environmental Systems, 7/10/2022) Wasserman, Marc; Weislogel, Mark; Mungin, Rihana; Hatch, Tyler; McQuillen, JohnA simple means of watering plants in the low-g environment aboard orbiting spacecraft is not obvious. Since the beginning of spaceflight, numerous approaches have been pursued to water plants that seek to maximize plant viability and system reliability, while minimizing crew time and system complexity. We are not there yet. The Plant Water Management (PWM) Soil experiments seek to apply recent advances in low-g capillary fluidics phenomena to the challenges faced by plant growth operations aboard spacecraft. The primary challenge is to establish earth-like flows minimizing low-g specific adaptations required of the plants. This is difficult due to the ever-present fluid physics challenges associated with poorly-wetting multiphase inertial-visco-capillary flows in geometrically complex conduits and containers�which change dramatically as the plants grow. In this paper, we present recent flight results for the simple visual PWM-Soil experiments where arcillite �soil reservoirs� are arranged in a non-wetting host soil that serves as an O2-breathing wetting barrier. In this way, a largely terrestrial water-soil environment might be mimicked where, as liquid is evapotranspired through the growing plant foliage, the effective water table passively �falls� reducing viscous lengths and increasing oxygenated water uptake for the plant. We present data from 6 days of 24-7 experiments on the ISS testing 3 different plant root models geometries. Not everything goes as planned as the �widely� varying plant models eventually perform similarly regarding total transport rate. We explain why via reference to a capillary flow model developed to capture the primary features of the flow. We summarize that successful passive capillary soil delivery systems can be designed at will, but the time/growth-dependent water requirements for plants in low-g environments may prove an elusive requirement.