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Development of closed life support systems for water recovery, oxygen generation and food processing is achievable in the future. However, currently the possibility of partial reproduction of food components from metabolic products and biocomplex waste should be taken into account when advanced life support system development is under consideration. Studies on carbohydrate synthesis from products of life are of particular interest because carbohydrates hold the first place in terms of mass in the food. The paper discusses possible ways of carbohydrate synthesis by physical/chemical means. Separate stages of a carbohydrate synthesis process are considered.

This paper reviews the design and properties of the Water Supply System (WSS). It also discusses the water balance and its delivery amounts, as well as it presents diagrams and properties of water recovery system from humidity condensate WRS-CM and regeneration from urine WRS-UM which are the part of WSS. Some results of activities conducted for provision of water intake in a system of WRS-CM from different modules of station are shown and the problems of WSS interaction of Russian segment (RS) and American segment (USOS) of the International Space Station (ISS) are discussed.

The dual membrane gas trap filter is utilized in the internal thermal control system (ITCS) as part of the pump package assembly to remove non-condensed gases from the ITCS coolant. This improves pump performance and prevents pump cavitation. The gas trap also provides the capability to vent air that is Ingested into the ITCS during routine maintenance and replacement of the International Space Station (ISS) system orbital replacement units. The gas trap is composed of two types of membranes that are formed into a cylindrical module and then encased within a titanium housing. The non-condensed gas that is captured is then allowed to escape through a vent tube in the gas trap housing.

The two-phase pump assembly (TPPA) supports advanced thermal control systems (TCS) being developed for future orbital and deep space missions that continuously demand technological advancements to reduce cost, schedule, size, and weight. The TCS provides cooling to onboard personnel and systems by utilizing a coolant in which the working fluid undergoes vaporization and condensation while circulating in the coolant fluid loop. The considerable latent heat associated with these liquid-vapor phase transitions allows the working fluid to absorb and transport a given amount of heat energy with a significantly reduced coolant flow rate resulting in a smaller system size, volume, and mass. Properly designed heat exchangers which utilize boiling and condensation phase transitions can be made smaller and lighter than single-phase systems for a given heat dissipation load.

Advanced space suit portable life support systems (PLSS) require high performance fans for the breathing gas ventilation system. AlliedSignal has developed a high speed air bearing fan for this application. This work addresses the development of an advanced electronic controller to drive this fan. Advances in space suit technology required an improved fan controller. The architecture of the controller was modified to enhance performance and facilitate testing in a space environment. These modifications were both physical and functional. To reduce the size of the controller, electrical, electronic and electromechanical (EEE) components were divided into two circuit cards, the housing was redesigned, test points and control knobs were removed, and a higher grade of EEE components were used in the development of the controller. These modifications improved the functional characteristics of the controller.

Bioreactor technology for waste water reclamation in a regenerative life support system (RLSS) is currently being developed by a team of NASA and major aerospace companies. To advance this technology, several activities are being performed concurrently; these include conducting small-scale studies and developing computer models. Small-scale studies are being performed to characterize and enhance the bioprocesses occurring within the bioreactor. New bioreactor configurations have been investigated which improved total organic carbon degradation as well as nitrification, the polishing step which converts nitrogenous wastes into forms that are easily removable from the water. Small-scale studies have also been performed using an activated sludge reactor demonstrating that TOC reduction and nitrification can occur in a single reactor. Computer models have been developed to guide the laboratory studies and to assist in full-scale system design.

Bioreactor technology is currently being developed by a team of NASA and major aerospace companies to provide capabilities for water reclamation within a Regenerative Life Support System (RLSS). An integrated approach is being used for this development process consisting of fundamental laboratory studies, full-scale experimental studies and mathematical modeling. The laboratory studies are focused on a series of identical bioreactors which are being used to develop an understanding of the kinetics, growth characteristics, and viability of the microbial population in the reactors through variation of key parameters. These studies have provided insight into system control issues, development of advanced reactor design concepts, and establishment of key parameter values for the mathematical modeling effort. The full-scale experimental studies are being used to develop a complete water reclamation system founded on a biologically-based primary water processor.

This paper reviews designs of urine distillation systems for spacecraft water recovery. Consideration is given to both air evaporation and vacuum distillation cycles, to the means for improving cycle performance (such as heat pumps, multistaging, and rotary evaporators), and to system concepts offering promise for future development. Vacuum distillation offers lower power consumption, at some increase in system complexity; air evaporation distillation is capable of providing higher water recovery efficiency, which could offset the lower power consumption advantage of vacuum distillation for long-duration missions.

The research conducted at NIICHIMMASH for the past several years in the area of Integrated Life Support System (ILSS) strategy development for technology efficiency analysis and system structure synthesis is reviewed in this paper. This study proposes an generalized efficiency model for ILSS development, which includes global, thermodynamic and local quantitative and qualitative factors. The research resulted in a strategy for the synthesis of ILSS structure based on evolutionary and integral- hypothhetical approaches. This strategy allows development of new system configurations, evaluation of existing ILSS effectiveness and considers decision marker's (DM) preferences. Uncertainty in the initial information about properties of the system or technology has a big influence on DM making decisions about future system appearance. Fuzzy set theory is used to define the uncertainty in the initial information.

The paper reviews one of the possible approaches to developing an analysis technique of Oxygen Generation System (OGS) thermal conditions. As an object of simulation a 30% KOH water electrolysis system with forced electrolyte circulation through the both electrolyzer chamber followed by separation of a gas/liqiud mixture using hydrophobic porous membranes. A formalized description of the key system components (an electrolyzer, set of coolers, separator, canister) is presented. A mathematical model simulating stationary and non-stationary thermal conditions of the system is constructed and its programming is reviewed. Some results of computational and operational experiments obtained for checking the model adecuacy are presented.

In the closed environment of an inhabited spacecraft, a critical aspect of the air revitalization system is the removal of the carbon dioxide (CO2) and water vapor produced by the crew. A number of different techniques can be used for CO2 removal, but current methods are either non-regenerative or require a relatively high power input for thermal regeneration. Two-bed CO2 adsorption systems that can remove CO2 from humid air and be regenerated using pressure-swing desorption offer mass, volume, and power advantages when compared with the other methods. Two classes of sorbent materials show particular promise for this application: Zeolite sorbents, similar to those in the International Space Station (ISS) CO2 removal assembly Functionalized carbon molecular sieves (FCMS), which adsorb CO2 independent of the humidity in the airstream Pressure-swing testing of these two different sorbents under both space station and space suit conditions are currently underway.

Space environmental control systems must control cabin temperature and humidity. This can be achieved by transferring the heat load to a circulating coolant, condensing the humidity, and separating the condensate from the air stream. In addition, environmental control systems may be required to remove particulate matter from the air stream. An assembly comprised of a filter, a condensing heat exchanger, a thermal control valve, and a liquid carryover sensor, is used to achieve all these requirements. A condensing heat exchanger and filter assembly (CHXFA) is being developed and manufactured by SECAN/AlliedSignal under a contract from Dornier Daimler-Benz as part of a European Space Agency program. The CHXFA is part of the environmental control system of the Columbus Orbital Facility (COF), the European laboratory module of the International Space Station (ISS).

Computer models are currently being developed by NASA and major aerospace companies to characterize regenerative life support waste water reclamation bioreactors. Detailed models increase understanding of complex processes within the bioreactors and predict performance capabilities over a wide range of operating parameters. Bench-top scale bioreactors are contributing to the development and validation of these models. The purpose of the detailed bioreactor model is to simulate the complex water purification processes as accurately as possible by minimizing the use of simplifying assumptions and empirical relationships. Fundamental equations of mass transport and microbial kinetics were implemented in a finite-difference model structure to maximize accuracy and adaptability to various bioreactor configurations. The model development is based upon concepts and data from the available literature and data from the bench top bioreactor investigations.

A condensing heat exchanger and filter assembly (CHXFA) has been developed by SECAN/AlliedSignal under a contract from Dornier Daimler-Benz as part of a European Space Agency program. The CHXFA is part of the Environmental Control and Life Support System (ECLSS) of the Columbus Orbital Facility (COF), the European Laboratory Module of the International Space Station (ISS). Although the COF CHXFA has a lifetime requirement of 10 years, some of the assembly components have been designated orbital replacement units (ORU's), which means that they must be designed to be replaceable “on-orbit”, in micro-gravity conditions. The CHXFA contains a filter to remove particulates from the air stream, and a differential pressure sensor to monitor pressure drop across the filter. The filter is a limited lifetime ORU, which will be periodically replaced as part of routine maintenance. The differential pressure sensor is also designated as an ORU.

This paper reviews the development and testing of the distillation subsystem of water regeneration system from urine (WRS-UM) based on a method of vacuum distillation with a rotary multistage vacuum distiller and a thermal pump. Test results show that with relatively small power consumption the subsystem using rotary three-stage vacuum distiller provides high rates of heat and mass transfer processes, useful productivity and distillate quality. The conducted tests have confirmed that it will be efficient to use the presented system as a part of WRS-UM system in Russian segment of the International Space Station.

Condensing heat exchangers (CHX) are used in many applications, including space life support systems, to control temperature and humidity. Temperature control is achieved by transfer of the heat load to a circulating coolant. Simultaneously, humidity control is provided by cooling the air below its dew point, and separating the condensed water from the gas flow. In space, the condensate does not drain from the heat exchanger because of the absence of gravity. To overcome this problem, slurping condensing heat exchangers have been developed that combine a hydrophilic coating on the air flow passages and an additional slurping section added to the air outlet of the heat exchanger to achieve efficient air-water separation. For short missions such as those typical for shuttle flights, microbial proliferation in the coatings has not been a major issue, despite the fact that the coatings are continuously moist and an ideal breeding ground for microbial species.

A regenerable metal oxide CO2 absorber is being developed for future Extravehicular Mobility Unit (EMU) applications. It was designed to fit the existing shuttle EMU without modification of the interfaces. Absorption and regeneration tests were performed with subscale and full-size laboratory absorbers. Data is presented for open and closed loop absorber tests that evaluate the effects of residence time, mass velocity, and internal temperature on performance, with emphasis is on the full-size test unit. Regeneration testing quantified the effects of temperature and air flow rate on desorption rate, and of various absorber cooling modes. Its objective was to optimize conditions for minimum peak power and minimum total energy consumption.

One of the primary safety concerns for Space Station Freedom pressurized modules is fire. Some Freedom modules are unattended for long periods of time. In other cases, enclosed, pressurized volumes are not open to crew monitoring. As a result, a fire detection system is required to continuously monitor all modules for combustion. This paper briefly reviews the overall design for the Freedom fire detection system, and the design of the two basic types of detectors: smoke and flame. The smoke detectors monitor particulates in small open areas, stand-offs, end-cones, and racks. The flame detectors survey open areas for radiation at wavelengths and intensities characteristic of combustion. Responses from detectors are evaluated by Freedom's data management system to determine the presence of combustion and to recommend appropriate action.

We present the development of a semiconductor diode laser spectral absorption based gas species sensor for oxygen concentration measurements, intended for life support system monitoring and control applications. Employing a novel self-compensating, noise cancellation detection approach, we experimentally demonstrate better than 1% accuracy, linearity, and stability for monitoring breathing air conditions with 0.2 second response time. We also discuss applications of this approach to CO2 sensing.

The paper describes the design specifics of the system for oxygen generation by electrolysis Elektron and major results obtained in long-term operation of the system aboard space station Mir. Operational data analysis makes possible to draw a conclusion that the system is capable to attain life parameters for at least 2 years with maintaining serviceability for no less than 8 years without attendance and unit replacement. Based on flight operation the possibility of reducing power consumption by 10 per cent is proven. System design updates are realized in the water electrolysis system intended for the Russian segment of the international space station.