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The Vapor Phase Catalytic Ammonia Removal (VPCAR) system is being developed to recycle water for future NASA Exploration Missions [1,2,3,4,5]. Reduced gravity testing of the VPCAR System has been initiated to identify any potential problems with microgravity operation. Two microgravity testing campaigns have been conducted on NASA's C-9B Reduced Gravity Aircraft. These tests focused on the fluid dynamics of the unit's Wiped-Film Rotating Disk (WFRD) evaporator. The experiments used a simplified system to study the process of forming a thin film on a rotating disk. The configuration simulates the application of feed in the VPCAR's WFRD evaporator. The first round of aircraft testing, which was completed in early 2006, indicated that a problem with microgravity operation of the WFRD existed. It was shown that in reduced gravity the VPCAR wiper did not produce a uniform thin film [6]. The film was thicker near the axis of rotation where centrifugal forces are small.

The future of manned space exploration will be determined through a process which balances the innate need of humanity to explore its surroundings and the costs associated with accomplishing these goals. For NASA this balance is derived from economics and budgetary constraints that hold it accountable for the expenditure of public funds. These budgetary realities demand a reduction in cost and expenditures of exploration and research activities. For missions venturing out to the edge of habitability, the development of cost effective life support approaches will have a significant influence on mission viability. Over the past several years a variety of mission scenarios for Lunar and Mars missions have been developed. The most promising of these attempt to provide basic mission requirements at a minimum cost. As a result these missions are extremely power limited.

This project is a Phase III SBIR contract between NASA and Water Reuse Technology (WRT). It covers the redesign, modification, and construction of the Wiped-Film Rotating-Disk (WFRD) evaporator for use in microgravity and its integration into a Vapor Phase Catalytic Ammonia Removal (VPCAR) system. VPCAR is a water processor technology for long duration space exploration applications. The system is designed as an engineering development unit specifically aimed at being integrated into NASA Johnson Space Center's Bioregenerative Planetary Life Support Test Complex (BIO-Plex). The WFRD evaporator and the compressor are being designed and built by WRT. The balance of the VPCAR system and the integrated package are being designed and built by Hamilton Sundstrand Space Systems International, Inc. (HSSSI) under a subcontract with WRT. This paper provides a description of the VPCAR technology and the advances that are being incorporated into the unit.

This paper presents the results of a program to develop the next generation Vapor Phase Catalytic Ammonia Removal (VPCAR) system. VPCAR is a spacecraft water recycling system designed by NASA and constructed by Water Reuse Technology Inc. The technology has been identified by NASA to be the next generation water recycling system [1]. It is designed specifically for a Mars transit vehicle mission. This paper provides a description of the process and an evaluation of the performance of the new system. The equivalent system mass (ESM) is calculated and compared to the existing state-of-the art. A description of the contracting mechanism used to construct the new system is also provided.

This paper describes the results of ground testing of a scroll pump with a potential of being a substitute for the current vacuum pump of the Vapor Phase Catalytic Ammonia Reduction (VPCAR). Assessments of the pressure-time, pump-down time, pump power and the pump noise were made for three configurations of the pump the first of which was without the gas ballast, the second with the gas ballast installed but not operating and the third with the gas ballast operating. The tested scroll pump exhibited optimum characteristics given its mass and power requirements. The pump down time required to reach a pressure of 50 Torr ranged from 60 minutes without the ballast to about 120 minutes with the gas ballast operational. The noise emission and the pump power were assessed in this paper as well.

An evaluation of a development Condensing Heat Exchanger (CHX) was conducted at the MSFC ECLS Test Facility. The purpose of this test was to assess the effect of particulates and metals in the CHX condensate on downstream components, primarily the Air/Water Separator and the Back Pressure Relief Valve (BPRV). This test was performed using a flight-like CHX to simulate the particulate load and the concentration of metals from the ISS CHX coating. Two designs of the flight BPRV used on ISS were tested to assess the effect of particulates on the valve operation. As expected, the original design of the BPRV showed it was susceptible to particulate blockage. Particulate levels were not as significant as those observed in condensate generated during ground tests of the Lab and Airlock modules.

Terraforming of Mars is the long-term goal of colonization of Mars. However, this process is likely to be a very slow process and conservative estimates involving a synergetic, technocentric approach suggest that it may take around 10,000 years before the planet can be parallel to that of Earth and where humans can live in open systems (Fogg, 1995). Hence, for the foreseeable future, any missions will require habitation within small confined habitats with high biomass to atmospheric mass ratios, thereby requiring that all wastes be recycled. Processing of the wastes will ensure predictability and reliability of the ecosystem and reduce resupply logistics. Solid wastes, though smaller in volume and mass than the liquid wastes, contain more than 90% of the essential elements required by humans and plants.

Presented is a synopsis of ongoing research into the development of techniques and hardware required to produce useable quantities of astrobiology relevant biomass under controlled and repeatable laboratory conditions. This study has developed microbial habitats (referred to as digesters, due to their biomass production function) capable of sustaining microbial communities under low temperature, high salt, high sulfate, anaerobic conditions. This set of basic conditions is necessary to develop biomass material that is analog to the biomass that would be present in subsurface brine habitats on Mars or Europa, from the perspective of several critical biochemical properties.

The Conductivity Sensor designed for use in the Node 3 Water Processor Assembly (WPA) was based on the existing Space Shuttle application for the fuel cell water system. However, engineering analysis has determined that this sensor design is potentially sensitive to two- phase fluid flow (gas/liquid) in microgravity. The source for this sensitivity is the fact that free gas will become lodged between the sensor probe and the wall of the housing without the aid of buoyancy in 1-g. Once gas becomes lodged in the housing, the measured conductivity will be offset based on the volume of occluded gas. A development conductivity sensor was flown on the NASA Microgravity Plane (KC-135) to measure the offset, which was determined to range between 0 and 50%. This range approximates the offset experienced in 1-g gas sensitivity testing.

This paper describes the results of performance testing of the Vapor Phase Catalytic Ammonia Removal (VPCAR) technology. The VPCAR technology is currently being developed by NASA as a Mars transit vehicle water recycling system. NASA has recently completed a grant to develop a next generation VPCAR system. This grant concluded with the shipment of the final deliverable from Water Reuse Technology Inc. to NASA on August 31, 2003. This paper presents the results of initial performance testing of the VPCAR-EDU. Mass, power, volume, and acoustic measurements are reported. Product water purity analysis for a Mars transit mission and a planetary base simulated wastewater feeds are also reported.

The Water Processor Assembly (WPA) for use on the International Space Station (ISS) includes various technologies for the treatment of waste water. These technologies include filtration, ion exchange, adsorption, catalytic oxidation, and iodination. The WPA hardware implementing portions of these technologies, including the Particulate Filter, Multifiltration Bed, Ion Exchange Bed, and Microbial Check Valve, was recently qualified for chemical performance at the Marshall Space Flight Center. Waste water representing the quality of that produced on the ISS was generated by test subjects and processed by the WPA. Water quality analysis and instrumentation data was acquired throughout the test to monitor hardware performance. This paper documents operation of the test and the assessment of the hardware performance.

Direct osmotic concentration (DOC) has been identified as a potential wastewater treatment process for potable reuse in advanced life support systems (ALSS). As a result, further development of the DOC process is being supported by a NASA Rapid Technology Development Team (RTDT) program. DOC is an integrated membrane system combining three unique membrane separation processes including forward osmosis (FO), membrane distillation (MD), and reverse osmosis (RO) that is designed to treat separate wastewater streams comprising hygiene wastewater, humidity condensate, and urine. An aqueous phase catalytic oxidation (APCO) process is incorporated as post treatment for the product water. In an ongoing effort to improve the DOC process and make it fully autonomous, further development of the three membrane technologies is being pursued.

Dewatering of wet waste during space exploration missions is important for crew safety as it stabilizes the waste. It may also be used to recover water and serve as a preconditioning step for waste compaction. A thermoelectric cooler (TEC)- driven lyophilizer is under development at NASA Ames Research Center for this purpose. It has three major components: (i) an evaporator section where water vapor sublimes from the frozen waste, (ii) a condenser section where this water vapor deposits as ice, and (iii) a TEC section which serves as a heat pump to transfer heat from the condenser to the evaporator. This paper analyses the heat and mass transfer processes in the lyophilizer in an effort to understand the ice formation behavior in the condenser. The analysis is supported by experimental observations of ice formation patterns in two different condenser units.

Novel mesoporous bimetallic oxidation catalysts are described, which are currently under development for the deep oxidation (mineralization) of aqueous organic contaminants in wastewater produced on-board manned spacecraft, and lunar and planetary habitats. The goal of the ongoing development program is to produce catalysts capable of organic contaminant mineralization near ambient temperature. Such a development will significantly reduce Equivalent System Mass (ESM) for the ISS Water Processor Assembly (WPA), which must operate at 135°C to convert organic carbon to CO2 and carboxylic acids. Improvements in catalyst performance were achieved due to the unique structural characteristics of mesoporous materials, which include a three-dimensional network of partially ordered interconnected mesopores (5-25 nm).

Mixed liquid/solid wastes, including feces, water processor effluents, and food waste, can be lyophilized (freeze-dried) to recover the water they contain and stabilize the solids that remain. Our previous research has demonstrated the potential benefits of using thermoelectric heat pumps to build a lyophilizer for processing waste in microgravity. These results were used to build a working prototype suitable for ground-based human testing. This paper describes the prototype design and presents results of functional and performance tests.

This paper presents results of research on a solid waste dryer, based of the process of lyophilization, which recovers water and stabilizes solid waste. A lyophilizer has been developed and tested that uses thermoelectric heat pumps (TECs) to recycle heat during drying. The properties of TECs facilitate direct measurement of heat flow rates, and heat flow data are used to evaluate a heat and mass transfer model of the thermoelectric lyophilizer. Data are consistent with the theoretical model in most respects. Practical problems such as insulation and vacuum maintenance are minor in this system. However, the model’s assumption of a uniformly retreating ice layer during drying is valid only for the first 30% of water removed. Beyond this point, a shrinking core or lens model is more appropriate. Heat transfer to the shrinking core surrounded by dried material is slow.

An energy-efficient lyophilization technique is being developed to recover water from highly contaminated spacecraft waste streams. In the lyophilization process, water in an aqueous waste is frozen and then sublimed, separating the waste into a dried solid material and liquid water. This technology is ideally suited to applications such as the Mars Reference Mission, where water recovery rates approaching 100% are desirable but production of CO2 is not. Candidate wastes include feces, concentrated brines from water processors, and other solid wastes that contain water. To operate in microgravity, and to minimize power consumption, thermoelectric heat pumps can be used in place of traditional fluid cycle heat pumps. A mathematical model of a thermoelectric lyophilizer is described and used to generate energy use and processing rate estimates.

The Lightweight Contingency Water Recovery System (LWC-WRS) harvests water from various sources in or around the Orion spacecraft in order to provide contingency water at a substantial mass savings when compared to stored emergency water supplies. The system uses activated carbon treatment (for urine) followed by forward osmosis (FO). The LWC-WRS recovers water from a variety of contaminated sources by directly processing it into a fortified (electrolyte and caloric) drink. Primary target water sources are urine, seawater, and other on board vehicle waters (often referred to as technical waters). The product drink provides hydration, electrolytes, and caloric requirements for crew consumption. The system hardware consists of a urine collection device containing an activated carbon matrix (Stage 1) and an FO membrane treatment element (or bag) which contains an internally mounted cellulose triacetate membrane (Stage 2).

The Lightweight Contingency (LWC) Urine System is a contingency urine recovery system that produces a liquid food product. It does this on an individual (personal) basis thus removing the concerns associated with shared urine recycle. The system uses activated carbon treatment followed by forward osmosis (FO) to provide a hydration and electrolyte fluid (a sports drink) for crew consumption. The system hardware consists of an initial urine collection device containing an activated carbon matrix. This is followed by transfer of the treated urine into an FO membrane treatment cell. The FO treatment cell consists of a 2 L plastic bag. This FO bag is a robustly constructed intravenous (IV) surgical fluid drip bag equipped with input and output ports and an internally mounted cellulose triacetate membrane. All components are light weight disposable plastic, the system is potentially wearable, and it uses no electrical power.

One of the largest single mass penalties required to support the human exploration of Mars is the surface habitat structural mass. Reducing the amount of structural material that must be launched from Earth to provide a habitat will reduce the cost of future missions. This paper describes the use of physical chemical technologies to produce high-density polyethylene for use as structural/construction materials from Mars atmospheric carbon dioxide. The formation of polyethylene from Mars carbon dioxide is based on the use of the Sabatier and modified Fischer Tropsch reactions. The system describe can be fully integrate with planned Mars in situ propellant production concepts.