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Three commercial off-the-shelf hollow fiber membrane evaporators, which were modified for low pressure, were tested as potential spacesuit water membrane evaporator (SWME) heat rejection technologies at pressures below 33 pascals in a vacuum chamber. Water quality was controlled in a series of 25 tests, first by simulating potable water that was reclaimed from wastewater and then by changing periodically to simulate the ever-concentrating make-up of the circulating coolant over that which is predicted over the course of 100 extravehicular activities. Two of the systems, which are comprised of nonporous tubes with hydrophilic molecular channels as the water vapor transport mechanism, were severely impacted by increasing concentrations of cations in the water. One of the systems, which was based on hydrophobic porous polypropylene tubes, was not affected by the degrading water quality or the presence of microbes. The polypropylene system, the SWME 1, was selected for further testing.

Performing extravehicular activity at various locations on the lunar surface presents thermal challenges that exceed those that have been experienced in space flight to date. The lunar Portable Life Support System (PLSS) cooling unit must maintain thermal conditions within the spacesuit (SS) and reject heat loads that are generated by both the crew member and the PLSS equipment. The amount of cooling that will be required varies based on lunar location and terrain due to the heat that is transferred between the suit and its surroundings, A study, which assumes three different thermal technology categories, has been completed that studied the resources that are required to provide cooling under various lunar conditions as follows: 1. SS water membrane evaporator 2. Sub-cooled phase change material (SPCM) 3.

A compact, low-power, electrochemically driven fluid cooling pump is currently being developed by Lynntech. With no electric motor and lightweight components, the pump is significantly lighter than conventional rotodynamic and displacement pumps. Reliability and robustness are achieved with the absence of rotating or moving components (apart from the bellows). By employing sulfonated polystyrene-based proton exchange membranes rather than conventional Nafion® membranes, a significant reduction in the actuator power consumption was demonstrated. Lynntech designers also demonstrated that these membranes possess the mechanical strength, durability, and temperature range that are necessary for long-life space operation. The preliminary design for a prototype pump compares very favorably to the design targets of the next generation spacesuit Portable Life Support Systems cooling pump.

An advanced Portable Life Support System for a future space suit will require a small, robust, and energy-efficient system to transport ventilation gas through the space suit for lunar Extravehicular Activity (EVA) operations. A trade study identified and compared ventilation transport technologies in commercial, military, and space applications to determine which technologies could be adapted for EVA use. Based on these trade study results, five commercially available, 24-V fans were selected for performance testing at various pressures and flow rates. Measured fan parameters included: fan delta-pressures, input voltages, input electrical currents, and, in some cases, motor windings electrical voltages and currents. A follow-on trade study was also performed to identify oxygen compatibility issues and assess their impact on fan design. This paper outlines the results of the fan performance characterization testing, as well as the results from the oxygen compatibility assessment.

Recovery of potable water from wastewater is essential to the success of long-duration human missions to the moon and Mars. Honeywell International and a team from the NASA Johnson Space Center (JSC) are developing a wastewater processing subsystem that is based on centrifugal vacuum distillation. The wastewater processor, which is referred to as the cascade distillation subsystem (CDS), uses an efficient multistage thermodynamic process to produce purified water. A CDS unit employing a five-stage distiller engine was designed, built, and delivered to the NASA JSC Advanced Water Recovery Systems Development Facility for performance testing; an initial round of testing was completed in fiscal year 2008 (FY08). Based, in part, on FY08 testing, the system is now in development to support an Exploration Life Support Project distillation comparison test that is expected to begin in 2009.

Metabolic heat regenerated temperature swing adsorption (MTSA) technology is being developed for removal and rejection of carbon dioxide (CO2) and heat from a portable life support system (PLSS) to the Martian environment. Previously, hardware was built and tested to demonstrate using heat from simulated, dry ventilation loop gas to affect the temperature swing required to regenerate an adsorbent used for CO2 removal. New testing has been performed using a moist, simulated ventilation loop gas to demonstrate the effects of water condensing and freezing in the heat exchanger during adsorbent regeneration. Also, the impact of MTSA on PLSS design was evaluated by performing thermal balances assuming a specific PLSS architecture. Results using NASA's Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT), a PLSS system evaluation tool, are presented.