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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.

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.

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.

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.

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.

When technologies are traded for incorporation into vehicle systems to support a specific mission scenario, they are often assessed in terms of “Technology Readiness Level” (TRL). TRL is based on three major categories of Core Technology Components, Ancillary Hardware and System Maturity, and Control and Control Integration. This paper describes the Technology Readiness Level assessment of the Carbon Dioxide Reduction Assembly (CRA) for use on the International Space Station. A team comprising of the NASA Johnson Space Center, Marshall Space Flight Center, Southwest Research Institute and Hamilton Sundstrand Space Systems International have been working on various aspects of the CRA to bring its TRL from 4/5 up to 6. This paper describes the work currently being done in the three major categories. Specific details are given on technology development of the Core Technology Components including the reactor, phase separator and CO2 compressor.