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The Regenerable Carbon Dioxide Removal System (RCRS) has been flying on Extended Duration Orbiter (EDO) versions of Shuttle since 1992. Life characteristics of an enhanced sorbent were evaluated after five years of service life on two Orbiter vehicles. Performance data is presented showing excellent carbon dioxide removal. Limited data forces a range of life predictions for the useful life of the sorbent.

A two-stage steam gasification and reforming process was evaluated for converting wastes generated within enclosed habitable environments into synthesis gas (CO & H2) and other recyclable inorganic species, i.e. water, CO2 and inorganic salts. Waste compounds used in the experimentation included: cellulose; urea; methionine; sucrose; butyric acid; Igepon TC-42 - a particularly (chemically) stable soap selected by NASA for use in space life support systems; wheat straw and a high density polyethylene. The compounds were tested individually and in combination to simulate the wastes anticipated within enclosed habitat environments.

A porous plate sublimator (an existing Lunar Module design) is being evaluated as the heat sink for the X-38 vehicle due to its simplicity, reliability, and flight readiness. It is ideally suited for the X-38/CRV as it requires no active control, has no moving parts, has 100 % water usage efficiency, and is a well-proven technology. This paper presents sublimator performance, including ground test data at CRV conditions, at both a component and system level. Potential sublimator modifications which could allow significant CRV ECLSS system simplification, reliability enhancement, and cost reduction are also discussed.

Hamilton Standard has been working on one EVA system concept which responds to NASA's design reference mission for the manned exploration of Mars early in the 21st century. Our concept uses a robotic support cart, to allow a simpler and lighter space suit and life support system. This, together with use of Martian resources, has shown the potential to satisfy mission needs. Present work includes preliminary design studies, analyses, and fabrication of a functional mock-up including the pressure garment, life support system, suit donning stand, and support cart. This paper describes our EVA system concept, the results of preliminary design analyses, and mock-up system tests, as well as some of the issues and challenges involved..

Pretreatment of urine using Oxone® and sulfuric acid is baselined in the International Space Station (ISS) waste water reclamation system to control odors, fix Ammonia and control microbial growth. In addition, pretreatment is recommended for long term flight use of urine collection and two phase separation to reduce or eliminate fouling of the associated hardware and plumbing with urine precipitates. This is important to the ISS application because the amount of maintenance time for cleaning and repairing hardware must be minimized. This paper describes the development of a chemical pretreatment system based on solid tablet shapes which are positioned in the inlet urine collection hose and are dissolved by the entrained urine at the proper ratio of pretreatment to urine. Building upon the prior success of the developed and tested solid Oxone tablet, a trade study and tests were completed to confirm if a similar approach would be appropriate for the sulfuric acid injection method.

Hamilton Standard Space Systems International, Inc. is currently under contract to NASA for the development and certification of an advanced technology regenerable carbon dioxide removal system for the International Space Station Extravehicular Mobility Unit (EMU), or “space suit.” This new metal-oxide-based system (“Metox”) will replace the existing non-regenerable lithium hydroxide (LiOH) carbon dioxide (CO2) removal system located in the EMU's Primary Life Support System (PLSS). The Metox canister is designed to replace the current LiOH Contamination Control Canister (CCC) with no modification to existing EMU interfaces. The metal oxide sorbent is “regenerable” and can be restored to its original condition permitting the Metox canisters to be used over and over again on-orbit. Once a Metox canister becomes “loaded” with CO2, it will be placed in the “Regenerator,” where the system will circulate hot air through the canister to drive off, or desorb, the CO2.

Hamilton Standard Space Systems International, Inc. (HSSSI) has obtained and is currently testing a variety of Russian life support hardware. These units have been or are contemplated for use on Mir I and II space stations. This paper presents the current status of performance testing of a Sabatier Carbon Dioxide Processing Unit (CDPU) and components of a Potable Water Processing System (PWP). These systems were fabricated by NIICHIMMASH, the supplier of these units to the Russian space program. It is the intent of this testing program to obtain a data base for technology comparisons to support planned and future international missions. For the CDPU, reactant conversion efficiencies in excess of 99 percent have been noted for the variation in test conditions with 2 to 6 man processing (flows) tested. The CDPU's effluent water has been produced at anticipated rates and is relatively contaminant free.

A distributed avionics air architecture provides air cooling and air circulation in non-habitable Space Station zones utilizing dedicated hardware to support the zone-specific needs. That dedicated hardware, the Avionics Air Assembly (AAA), includes a selectable speed fan and heat exchanger used in racks for active avionics air cooling to reject the airborne heat load directly to the moderate temperature Internal Thermal Control System (ITCS). This paper addresses the design impacts resulting from the International Space Station Alpha (ISSA) restructure effort. It defines the service provided by the avionics air assembly, the design requirements and the integrated system performance. Detailed package configuration and interfaces, hardware design and off-design performance are included to define the full range of operating capability.

Shuttle Extravehicular Mobility Unit (EMU) studies have shown that the thermal interaction between the crewperson, liquid cooling garment and EMU thermal management system is highly transient in nature. Recent investigations of these phenomena provide a better understanding which have helped improve thermal comfort in the present system. Analyses show that the key to thermal comfort is understanding the interaction between physiological responses and EMU system thermal transients. A test program was conducted to evaluate the theorized causes of discomfort and proposed corrective actions. Several EMU thermal management related modifications were utilized in the Hubble Space Telescope repair mission where five, two crewperson ExtraVehicular Activities (EVAs) were conducted without any thermal discomfort in a mildly cold environment.

In 1991, Hamilton Standard initiated an Independent Research and Development program to enhance the performance characteristics of solid amine based regenerative CO2 removal systems. A solid amine based system had been selected by NASA/JSC for Extended Duration Orbiter missions. As a result of this research effort, two promising new solid amine candidates, designated HSC+ and HSG, were identified. Bench scale testing indicated that these formulations provided 25% to 33% greater initial cyclic capacity when compared to the baseline HSC solid amine sorbent. This paper reports on comparative life testing of HSC, HSC+ and HSG. The solid amine sorbents were exposed to accelerated life testing with laboratory air under controlled temperature and flow conditions.

The International Space Station Alpha Electrical Power System has a thermal control system to remove heat from the batteries and power distribution electronics. A major subsystem of this thermal loop is the Pump and Flow Control Subassembly (PFCS) which functions as an ammonia fluid distribution and control subsystem. This paper will detail the development, construction and operational performances of the PFCS hydraulic elements operating with an ammonia fluid. These elements include flow meter, accumulator, flow control valve, and pumps. The electronics which are utilized to operate these hydraulic elements will also be described. The combination of these hydraulic and electronic elements form a subassembly to safely control a hazardous, low viscosity fluid.

The Avionics Air Assembly Cooling Package which provides cooling for high heat load racks aboard the International Space Station has been designed and developed to balance challenging requirements for noise emissions, emitted vibrations, power usage, weight, and volume. The assembly consists of a high speed selectable flow fan, a compact air-to-water heat exchanger, noise attenuation components, motor controller electronics, and mounting structure. This paper addresses the final hardware configuration and performance characteristics and the successful development program that was required to create the first qualification/flight assembly. It describes the initial component development hardware performance, the initial package integration results, the completed optimization effort, and the final package performance. These optimization cycles, both to improve and reduce component performance, were necessary to attain the desired package results from this highly integrated assembly.

Based on the high volume of Extravehicular Activity (EVA) needed for assembly and operation of the International Space Station (1792 hrs through GFY2005), a large number of new crewmembers will be trained in the use of the Extravehicular Mobility Unit (EMU). In addition, the crewmembers will require on-orbit refresher training in the use of an EMU given their extended duration on-orbit of 90-180 days. Currently, there is a single hardware based training unit at Johnson Spaceflight Center (JSC) (the MALF II Simulator). This paper reports on the development of a software based training simulator (EMU Malfunction Training Simulator [EMTS]) which will run on any PC under Microsoft Windows and will be used to supplement MALF II.

The TIMES is an evaporative water processor which has shown great theoretical potential for providing reliable and efficient production of high quality water. The test results of the system have however fallen short of the predicted performances. A thorough systems analysis has identified the condensing heat exchanger as a primary source of the shortcomings of the assembly. This condenser, along with three other heat exchangers in the system, have been redesigned and integrated into a new “Regenerator” that is predicted to significantly lower the power consumption and improve both the operating stability and product water quality.

The Extravehicular Mobility Unit (EMU) used by astronauts during space walks is powered by an 11-cell, silver-zinc battery. The present battery is certified for 6 cycles with a minimum discharge requirement of 7 hours above 16.0 volts at a 3.8 Amp load. Its certified wet-life is 170 days. Operational requirements for the International Space Station (ISS) led to a design capable of 32 cycles over a 425 day wet-life. Other battery parameters including capacity, rate capability, weight, volume, safety and the need for continuing compatibility with the EMU and the Space Shuttle charger dictate that the new battery will also be silver-zinc.

Hamilton Standard’s subsidiaries, Microtecnica/Italy and Hamilton Standard Space Systems International/USA, have collaborated to design and fabricate a Water Pump Package (WPP) for the International Space Station (ISS) Multi-Purpose Logistics Module (MPLM). MPLM active payloads (Refrigerator/Freezer Racks (R/FR)) supply cold volume for food and scientific sample storage. The MPLM Active Thermal Control Subsystem (ATCS) maintains specific structural and equipment temperatures for the active payloads. The active thermal control is provided via a low temperature water loop whose flow rate is created by the WPP during MPLM pre-launch and MPLM pre-ISS attach and post-ISS detach mission phases. The WPP also provides compensation for water loop volume variations. This paper will provide a detailed overview of the MPLM Water Pump Package design, as well as providing system performance data.

A porous plate sublimator (based on an existing Lunar Module LM-209 design) is baselined as a heat rejection device for the X-38 vehicle due to its simplicity, reliability, and flight readiness. The sublimator is a passive device used for rejecting heat to the vacuum of space by sublimating water to obtain efficient heat rejection in excess of 1,000 Btu/lb of water. It is ideally suited for the X-38/CRV mission as it requires no active control, has no moving parts, has 100% water usage efficiency, and is a well-proven technology. Two sublimators have been built and tested for the X-38 program, one of which will fly on the NASA V-201 space flight demonstrator vehicle in 2001. The units satisfied all X-38 requirements with margin and have demonstrated excellent performance. Minor design changes were made to the LM-209 design for improved manufacturability and parts obsolescence.

The generation (and recovery) of water, rather than the reduction of CO2, drives the requirements for the integration of a Sabatier CO2 Reduction Subsystem (SCRS) within an Air Revitalization Subsystem (ARS). It is important, therefore, to understand the system level decisions that impact the water production capability of the Sabatier CO2 Reduction Subsystem. This paper defines each of the operational parameters that affect water production and loss and explores the impact they each have on total water recovery. The particular subsystem parameters examined include hydrogen and carbon dioxide flow rates, feed gas composition, subsystem operating pressure, condensing heat exchanger performance, heat sink temperature, and phase separator performance. Each of these has a minor contribution to the amount of water lost from the system, but combined, their effect is substantial.

The International Space Station's primary external heat transport system is a single phase ammonia loop called the Active Thermal Control System (ATCS). ATCS loop heat is acquired from the station modules through interface heat exchangers (Internal Thermal Control System water to ATCS ammonia) and from external truss mounted electronics through cold plates. The heat exchangers are compact plate/fin counterflow type and the cold plates are a brazed and bonded construction using a radiation heat transfer interface to the electronics.