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Dean Leslie Muirhead

Publications and source records attributed to Dean Leslie Muirhead.

Development of a Planetary Water Treatment System

As NASA prepares for human missions beyond the International Space Station (ISS), NASA personnel have begun development of a water treatment system that is optimized for operation on the Moon and Mars. This system will take advantage of the partial gravity of surface-based habitats while minimizing resupply mass and ensuring optimum reliability. An overview of expected water uses, waste streams, and architectures for a partial gravity water recovery system (WRS) is presented and compared to the WRS on ISS. This paper summarizes the current progress of evaluating various technologies and architectures for the potential mission profiles currently being considered.

Dean Leslie Muirhead↗

A Review of Baseline Assumptions and Ersatz Waste Streams for Partial Gravity Habitats and Orbiting Micro-gravity Habitats

Highly efficient water management and recovery systems will be required to support human missions beyond the low Earth orbit of the International Space Station (ISS). A review of baseline assumptions for the human activities and associated water cycle in surface, partial gravity habitats and orbiting, microgravity habitats is conducted. The paper reviews and updates ersatz formulations and water flow rates for the main liquid water waste streams of urine, humidity condensate, hygiene, and laundry. Development of a new framework is recommended to coordinate advancement and commonalities of water recovery systems for 30- day crew occupancies under partial gravity with longer term, continuous occupancy in surface or orbiting microgravity habitats and the Mars transit habitat.

Dean Leslie Muirhead↗

To Biocide or not to Biocide? Exploring the "No Biocide" Option in Spacecraft Potable Water Systems

Residual biocide has been used to protect against microbial growth in spacecraft potable water systems since the Gemini program. Iodine, the biocide currently used on the International Space Station (ISS) has a long history of use but presents a few challenges for exploration: it must be removed using a consumable absorbent before crew consumption and is known to lose its biocidal concentration due to interactions with wetted components, especially during periods of dormancy. Biocidal silver is being considered for exploration missions as it is safe for crew consumption, but it too has challenges with proper material design to maintain sufficient disinfection residuals. An idea proposed by some in the Environmental Control and Life Support System (ECLSS) community has been that the biocide does not provide a true barrier against microbial growth, and therefore, perhaps the challenges of maintaining a residual biocide in the system could be best overcome by removing the biocide altogether. In this argument, they point to the regenerative water treatment system on the ISS which produces high purity water that theoretically meets the microbiological requirements before the iodine is added. Exploration water processing systems are expected to have similar water processing capabilities. This paper will discuss the role that residual biocide may play in controlling microbial growth and presents perspectives on the potential risks associated with removing it from exploration water systems.

biocide↗

Baseline Assumptions and Ersatz Waste Streams for Partial Gravity Habitats with Mobile Female and Male Crew

Effective and reliable water management and recovery systems will be required to sup-port human missions beyond the low Earth orbit (LEO) of the International Space Station (ISS). Lunar and Mars surface missions will introduce new challenges to managing water and associated waste streams from mobile crew members who will be living in up to six shelters in extreme environmental conditions under a range of gravity conditions. A review of baseline assumptions for the human activities and associated air and water cycles in and between the transit vehicle, orbiting station, lander-ascent vehicle, surface habitat, pressurized rover, and suits is conducted. The paper reviews ersatz formulations and water flow rates for the main liquid water waste streams of urine, humidity condensate, hygiene, and laundry. Emphasis is placed on the metabolic emissions partitioning between the six habitat elements and the lunar exosphere during a design reference mission scenario.

Water Ersatz Habitat↗

Baseline Assumptions and Ersatz Waste Streams for Partial Gravity Habitats with Mobile Female and Male Crew

Effective and reliable water management and recovery systems will be required to sup-port human missions beyond the low Earth orbit (LEO) of the International Space Station (ISS). Lunar and Mars surface missions will introduce new challenges to managing water and associated waste streams from mobile crew members who will be living in up to six shelters in extreme environmental conditions under a range of gravity conditions. A review of baseline assumptions for the human activities and associated air and water cycles in and between the transit vehicle, orbiting station, lander-ascent vehicle, surface habitat, pressurized rover, and suits is conducted. The paper reviews ersatz formulations and water flow rates for the main liquid water waste streams of urine, humidity condensate, hygiene, and laundry. Emphasis is placed on the metabolic emissions partitioning between the six habitat elements and the lunar exosphere during a design reference mission scenario.

Water Ersatz Habitat↗