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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.

The vast array of C-130 applications demand a variety of air conditioning solutions to meet the specific needs of each variant and its user. Existing C-130′s are often reconfigured for special use such as airborne early warning and control (AEW&C), electronic surveillance, or armed reconnaissance, or just upgraded to current flight standards where new equipment is added to the aircraft that significantly increases the heat load on the air conditioning system. These factors dictate the need for high-, middle-, and low-end solutions to deliver the increased cooling capacity required at a price each user can afford. This paper will recap the evolution of the C-130 environmental control system (ECS) to date, summarize current improvement efforts, and suggest future ECS developments.

The Lunar-Mars Life Support Test Project (LMLSTP) Phase III test examined the use of biological and physicochemical life support technologies for the recovery of potable water from waste water, the regeneration of breathable air, and the maintenance of a shirt-sleeve environment for a crew of four persons for 91 days. This represents the longest duration ground-test of life support systems with humans performed in the United States. This paper will describe the test from the inside viewpoint, concentrating on three major areas: maintenance and repair of life support elements, the scientific projects performed primarily in support of the International Space Station, and numerous activities in the areas of public affairs and education outreach.

In-situ production of oxygen and methane for utilization as a return propellant from Mars for both sample-return and manned missions is currently being developed by NASA in cooperation with major aerospace companies. Various technologies are being evaluated using computer modeling and analysis at the system level. An integrated system that processes the carbon dioxide in the Mars atmosphere to produce liquid propellants has been analyzed. The system is based on the Sabatier reaction that utilizes carbon dioxide and hydrogen to produce methane and water. The water is then electrolyzed to produce hydrogen and oxygen. While the hydrogen is recycled, the propellant gases are liquefied and stored for later use. The process model considers the surface conditions on Mars (temperature, pressure, composition), energy usage, and thermal integration effects on the overall system weight and size. Current mission scenarios require a system that will produce 0.7 kg of propellant a day for 500 days.

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.

The Lunar-Mars Life Support Test Project (LMLSTP), formerly known as the Early Human Testing Initiative (EHTI), was established to perform the necessary research, technology development, integration, and verification of regenerative life support systems to provide safe, reliable, and self-sufficient human life support systems. Four advanced life support system test phases make up LMLSTP. Phase I of the test program demonstrated the use of plants to provide the atmosphere revitalization requirements of a single test subject for 15 days. The primary objective of the Phase II test was to demonstrate an integrated regenerative life support system capable of sustaining a human crew of four for 30 days in a closed chamber. The third test phase, known as Phase IIA, served as a demonstration of International Space Station (ISS) representative life support technology, supporting a human crew of four for 60 days.

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).

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.

Biological wastewater processing has been under investigation by AlliedSignal Aerospace and NASA Johnson Space Center (JSC) for future use in space. Testing at JSC in the Hybrid Regenerative Water Recovery System (HRWRS) in preparation for future closed human testing has been performed. Computer models have been developed to aid in the design of a new four-person immobilized cell bioreactor. The design of the reactor and validation of the computer model is presented. In addition, the total organic carbon (TOC) computer model has been expanded to begin investigation of nitrification. This model is being developed to identify the key parameters of the nitrification process, and to improve the design and operating conditions of nitrifying bioreactors. In addition, the model can be used as a design tool to rapidly predict the effects of changes in operational conditions and reactor design, significantly reducing the number and duration of experiments required.

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.

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.

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.

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.

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.

Reversible adsorption on zeolite molecular sieve material allows selective removal of carbon dioxide (CO2) from spacecraft air without the use of expendables. The four-bed molecular sieve (4BMS) CO2 removal subsystem chosen for use on space station is based on proven Skylab technology and provides continuous CO2 removal from the cabin atmosphere and concentration for further processing downstream or venting overboard. A 4BMS subsystem has also been chosen to remove CO2 from air in the Systems Integration Research Facility (SIRF) at NASA/Johnson Space Center (JSC). After installation in the SIRF in 1992, the subsystem underwent extensive testing in which cycle time, process air flow rate, and process air inlet CO2 composition were varied. In order to obtain performance data required for integration, the subsystem was operated under both nominal and off-nominal conditions. Results of this testing are presented.

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.