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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.

Catalytic oxidation is an effective means of controlling the build up of ammonia and other trace gas contaminants within closed spaces. However, it sometimes leads to the formation of noxious gases that need to be removed in post-treatment systems. In addition, ammonia removal is an issue when regeneration of water from wastewater is considered since ammonia is a byproduct of urea decomposition. For example, the VPCAR (Vapor Phase Catalytic Ammonia Reduction) advanced water processor system includes an oxidation reactor for the destruction of ammonia and of other volatile organics that are not separated out in the evaporator due to their volatility. The oxidation of ammonia may produce nitrogen, nitrogen oxides (NO and NO2), nitrous oxide (N2O) and water vapor. The Spacecraft Maximum Allowable Concentration (SMAC) for NO and NO2 are respectively 4.5 and 0.5 ppm whereas the Threshold Limit Value (TLV) for N2O is 25 ppm.

Hamilton Sundstrand Space Systems International, Inc. (HSSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop a Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) for the international Space Station (ISS). The WPA produces potable quality water from humidity condensate, carbon dioxide reduction water, water obtained from fuel cells, reclaimed urine distillate, hand wash and oral hygiene waste waters. The Oxygen Generation Assembly (OGA) electrolyzes potable water from the Water Recovery System (WRS) to provide gaseous oxygen to the Space Station module atmosphere. The OGA produces oxygen for metabolic consumption by crew and biological specimens. The OGA also replenishes oxygen lost by experiment ingestion, airlock depressurization, CO2 venting, and leakage. As a byproduct, gaseous hydrogen is generated. The hydrogen will be supplied at a specified pressure range to support future utilization.

The International Space Station (ISS) IATCS (Internal Active Thermal Control System) includes two internal coolant loops that use an aqueous based coolant for heat transfer. A silver salt biocide was used initially as an additive in the coolant formulation to control the growth and proliferation of microorganisms in the coolant loops. Ground-based and in-flight testing has demonstrated that the silver salt is rapidly depleted and not effective as a long-term biocide. Efforts are now underway to select an alternate biocide for the IATCS coolant loop with greatly improved performance. An extensive evaluation of biocides was conducted to select several candidates for test trials.

The ISS (International Space Station) ITCS (Internal Thermal Control System) includes two internal coolant loops that utilize an aqueous based coolant for heat transfer. A silver salt biocide had previously been utilized as an additive in the coolant formulation to control the growth and proliferation of microorganisms within the coolant loops. Ground-based and in-flight testing demonstrated that the silver salt was rapidly depleted, and did not act as an effective long-term biocide. Efforts to select an optimal alternate biocide for the ITCS coolant application have been underway and are now in the final stages. An extensive evaluation of biocides was conducted to down-select to several candidates for test trials and was reported on previously.

Carbon dioxide reduction in a closed loop life support system recovers water from otherwise waste carbon dioxide and hydrogen. Incorporation of a carbon dioxide reduction assembly (CRA) into the International Space Station life support system frees up thousands of pounds of payload capacity in the supporting Space Shuttle that would otherwise be required to transport water. Achievement of this water recovery goal requires coordination of the CRA design to work within the existing framework of the interface systems that are either already on orbit or well advanced in their development; namely, the Oxygen Generator Assembly (OGA), Carbon Dioxide Removal Assembly (CDRA) and Water Processor Assembly (WPA). The Oxygen Generation System (OGS) rack is in its final design phase and is scarred to accept later installation of the CRA.

A trade study conducted in 2001 selected a rotary disk separator as the best candidate to meet the requirements for an International Space Station (ISS) Carbon Dioxide Reduction Assembly (CRA). The selected technology must provide micro-gravity gas/liquid separation and pump the liquid from 69 kPa (10 psia) at the gas/liquid interface to 124 kPa (18 psia) at the wastewater bus storage tank. The rotary disk concept, which has pedigree in other systems currently being built for installation on the ISS, failed to achieve the required pumping head within the allotted power. The separator discussed in this paper is a new design that was tested to determine compliance with performance requirements in the CRA. The drum separator and pump (DSP) design is similar to the Oxygen Generator Assembly (OGA) Rotary Separator Accumulator (RSA) in that it has a rotating assembly inside a stationary housing driven by a integral internal motor[1].

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.

Designing an EVA system for Mars’s exploration will require a thorough understanding of the mission. Data are available from NASA mission studies, preliminary EVA requirements document, and Apollo program experience. However, additional relevant field experience is required to complete the picture. NASA has addressed this through field tests using prototype EVA equipment and field science programs like the Haughton Mars Project on Devon Island. There, a group of scientists conducts scientific exploration in and around an impact crater in a polar desert similar to expected exploration sites on Mars. Hamilton Sundstrand Space Systems Intl. (HSSSI) EVA system engineers participated in the summer 2000 field research program to gain firsthand knowledge of field science activities. By using a Mars EVA system mockup, they were also able to conduct experiments on EVA system impacts on field science tasks. This field experience and some of its results are described in this paper.

The International Space Station Waste Collector Subsystem Risk Mitigation Experiment (ISS WCS RME) was flown as the primary (Shuttle) WCS on Space Shuttle flight STS-104 (ISS-7A) in July 2001, to validate new design enhancements. In general, the WCS is utilized for collecting, storing, and compacting fecal & associated personal hygiene waste, in a zero gravity environment. In addition, the WCS collects and transfers urine to the Shuttle waste storage tank. All functions are executed while controlling odors and providing crew comfort. The ISS WCS previously flew on three Shuttle flights as the Extended Duration Orbiter (EDO) WCS, as it was originally designed to support extended duration Space Shuttle flights up to 30 days in length. Soon after its third flight, the Space Shuttle Program decided to no longer require 30 day extended mission duration capability and provided the EDO WCS to the ISS Program.

Enhancements to the Regenerable Carbon Dioxide Removal System (RCRS) have undergone full-scale, pre-prototype development and testing to demonstrate a redundant system within the volume allotted for the RCRS on the Space Shuttle Orbiter. The concept for a Redundant Regenerable Carbon Dioxide Removal System (RRCRS) utilizes the existing canister of the RCRS, but partitions it into two, independent, two-bed systems. This partitioning allows for two, fully capable RCRS units to be packaged within the original volume, thus reducing stowage volume and launch weight when compared to the flight RCRS plus the backup LiOH system. This paper presents the results of development and testing of a full-scale, pre-prototype RRCRS and includes an overview of the design concept for a redundant system that can be packaged within the existing envelope.

A Rotary Separator/Accumulator (RSA) has been developed to function as a phase separator and accumulator in the Oxygen Generator Assembly (OGA) in the microgravity environment of the International Space Station. The RSA design utilizes a fixed housing with rotating disks to create a centrifugal force field to separate hydrogen gas from water. The volume within the assembly is utilized to act as an accumulator for the OGA. During the development of the RSA, design refinements were made to meet the changing system operating requirements. Two proof of concept (POC) units and a “flight-like” development unit were fabricated and tested as system requirements evolved. Testing of the first POC unit demonstrated that a combined rotary separator and accumulator was feasible and showed areas where improvements could be made. The second POC unit incorporated a fifty percent volume increase to accommodate changing system requirements and geometry changes to help reduce power consumption.

The Water Processor developed for the International Space Station includes a high temperature catalytic reactor that utilizes oxygen gas to oxidize dissolved chemicals. The effluent from the reactor is a mixture of gases (O2, CO2, N2) and hot water. Since the crew has requested that drinking water does not contain any free gas at body temperature (37.8 °C or 100 °F), a phase separator operating at elevated temperatures is required downstream of the catalytic reactor. For this application, Hamilton Sundstrand Space Systems International (HSSSI) has developed a passive Gas Liquid Separator (GLS) that relies on a positive barrier - a membrane - to extract the free gas from the inlet two-phase mixture. The membrane selected is a hollow fiber hydrophobic asymmetric membrane with pore size in the ultra-filtration range. This paper outlines the challenges in both design and operation that were overcome during the development of this device.

The purification of waste water is a critical element of any long-duration space mission. The Vapor Phase Catalytic Ammonia Removal (VPCAR) system offers the promise of a technology requiring low quantities of expendable material that is suitable for exploration missions. NASA has funded an effort to produce an engineering development unit specifically targeted for integration into the NASA Johnson Space Center's Integrated Human Exploration Mission Simulation Facility (INTEGRITY) formally known in part as the Bioregenerative Planetary Life Support Test Complex (Bio-Plex) and the Advanced Water Recovery System Development Facility. The system includes a Wiped-Film Rotating-Disk (WFRD) evaporator redesigned with micro-gravity operation enhancements, which evaporates wastewater and produces water vapor with only volatile components as contaminants. Volatile contaminants, including organics and ammonia, are oxidized in a catalytic reactor while they are in the vapor phase.

Hamilton Sundstrand Space Systems International, Inc. (HSSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop, an Oxygen Generation Assembly (OGA) for the International Space Station (ISS). The Oxygen Generation Assembly (OGA) electrolyzes potable water from the Water Recovery System (WRS) to provide gaseous oxygen to the Space Station module atmosphere. The OGA produces oxygen for metabolic consumption by crew and biological specimens. The OGA also replenishes oxygen lost by experiment ingestion, airlock depressurization, CO2 venting, and leakage. As a byproduct, gaseous hydrogen is generated. The hydrogen will be supplied at a specified pressure range to support future utilization. Initially, the hydrogen will be vented overboard to space vacuum. The OGA has been under development at HSSSI for 3 years. This paper will update last year's ICES paper on the design/development of the OGA.

Hamilton Sundstrand Space Systems International, Inc. (HSSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop a Water Processor Assembly (WPA) for the International Space Station (ISS). The WPA produces potable quality water from humidity condensate, carbon dioxide reduction water, water obtained from fuel cells, reclaimed urine distillate, shower, handwash and oral hygiene wastewaters. All planned development testing has been completed and this paper provides the status of the development activities and results for the WPA.

Hamilton Sundstrand Space Systems International, Inc. HSSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop a Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) for the International Space Station (ISS). The WPA produces potable quality water from humidity condensate, carbon dioxide reduction water, water obtained from fuel cells, reclaimed urine distillate, shower, handwash and oral hygiene waste waters. The Oxygen Generation Assembly (OGA) electrolyzes potable water from the Water Recover System (WRS) to provide gaseous oxygen to the Space Station module atmosphere. The OGA produces oxygen for metabolic consumption by crew and biological specimens. The OGA also replenishes oxygen lost by experiment ingestion, airlock depressurization, CO2 venting, and leakage. As a byproduct, gaseous hydrogen is generated. The hydrogen will be supplied at a specified pressure range to support future utilization.

Hamilton Sundstrand Space Systems International, Inc. (HSSSI) is under contract to NASA Marshall Space Flight Center (MSFC) to develop a Water Processor Assembly (WPA) and Oxygen Generation Assembly (OGA) for the International Space Station (ISS). The WPA produces potable quality water from humidity condensate, carbon dioxide reduction water, water obtained from fuel cells, reclaimed urine distillate, shower, handwash and oral hygiene waste waters. The Oxygen Generation Assembly (OGA) electrolyzes potable water from the Water Recovery System (WRS) to provide gaseous oxygen to the Space Station module atmosphere. The OGA produces oxygen for metabolic consumption by crew and biological specimens. The OGA also replenishes oxygen lost by experiment ingestion, airlock depressurization, CO2 venting, and leakage. As a byproduct, gaseous hydrogen is generated. The hydrogen will be supplied at a specified pressure range to support future utilization.

A Low Pressure Electrolyzer (LPE) is being developed to provide metabolic oxygen aboard US nuclear submarines. The system is derived from a more complex system already developed for the Virginia Class of attack submarines. The LPE generates up to 250 standard cubic feet per hour (SCFH) of oxygen at ambient pressure through electrolysis of water utilizing SPE® (Solid Polymer Electrolyte) technology. The hydrogen is generated at pressures suitable for disposal overboard. The system operates unattended which minimizes crew workload, and can safely shut down without crew intervention. Generating oxygen at ambient pressure significantly reduces risk to personnel and greatly simplifies the system. Reliability, maintainability, safety, and ease of operation are major system design drivers.

Hamilton Sundstrand Space Systems International (HSSSI) is currently under contract with NASA MSFC to design, fabricate and deliver the Water Processor Assembly (WPA) for the International Space Station (ISS). As part of this effort HSSSI has developed an oxidation catalyst for the catalytic reactor assembly in the WPA. This paper discusses full-scale development reactor testing and the status of the life testing of the oxidation catalyst used in the reactor.