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In preparation for the contract award of the Crew Exploration Vehicle (CEV), the National Aeronautics and Space Administration (NASA) produced two design reference missions for the vehicle. The design references used teams of engineers across the agency to come up with two configurations. This process helped NASA understand the conflicts and limitations in the CEV design, and investigate options to solve them.

The paper provides a summary of current work accomplished under technical task agreement (TTA) by the Marshall Space Flight Center (MSFC) regarding the Environmental Control and Life Support System (ECLSS) as well as future planning activities in support of the International Space Station(ISS).Current activities computer model development, component design and development, subsystem/integrated system testing, life testing, and government furnished equipment delivered to the ISS program. A long range plan for the MSFC ECLSS test facility is described whereby the current facility would be upgraded to support integrated station ECLSS operations. ECLSS technology development efforts proposed to be performed under the Advanced Engineering Technology Development (AETD) program are also discussed.

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.

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.

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).

Advanced life support flight experiments have been conceptualized for the International Space Station (ISS). Two of the experiments, a high pressure oxygen generator and a carbon dioxide reduction subsystem, offer high payback potential to the ISS program. This paper documents the cost-benefit analyses for these two experiments.

A two year test program has been initiated to evaluate the effects of extended duration operation on a solid polymer electrolyte Oxygen Generator Assembly (OGA); in particular the cell stack and membrane phase separators. As part of this test program, the OGA was integrated into the Marshall Space Flight Center (MSFC) Water Recovery Test (WRT) Stage 10, a six month test, to use reclaimed water directly from the water processor product water storage tanks. This paper will document results encountered and evaluated thus far in the life testing program.

A dynamic model of a top fuel dragster performance is presented. This model represents a four-degree-of-freedom system involving a set of nonlinear differential equations of motion. Drive-train angular motion, pitching chassis motion, rear tires deflection and diameter growth, variable mass moment of inertia, and traction characteristics are included. Engine characteristics and set-up are also incorporated in the model. Numerical simulations are made to investigate the effect of aerodynamics and engine initial torque on performance. The numerical results suggest that a reduction in elapsed time can be achieved if the conditions are appropriate.

An austere fiscal environment in the aerospace community creates pressure to reduce program costs, often minimizing or even deleting human interface requirements from the design process. With the assumption that the flight crew can recover, in real time, from a poorly human factored space vehicle design, the classical crew interface requirements have either been not included in the design or not properly funded, even though they are carried as requirements. Cost cuts have also affected the quality of retained human factors engineering personnel. Planning is ongoing to correct these issues. Herein are techniques for ensuring that human interface requirements are integrated with flight design from proposal through verification and launch activation.

The paper describes a methodology to co-simulate, with high fidelity, simultaneously and in one computational framework, all of the main vehicle subsystems for improved engineering design. The co-simulation based approach integrates in MATLAB/Simulink a physics-based tire model with high fidelity vehicle dynamics model and an accurate powertrain model allowing insights into 1) how the dynamics of a vehicle affect fuel consumption, quality of emission and vehicle control strategies and 2) how the choice of powertrain systems influence the dynamics of the vehicle; for instance how the variations in drive shaft torque affects vehicle handling, the maximum achievable acceleration of the vehicle, etc. The goal of developing this co-simulation framework is to capture the interaction between powertrain and rest of the vehicle in order to better predict, through simulation, the overall dynamics of the vehicle.

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.

A program is being performed to design, fabricate, and test a metal hydride sorption cryocooler system capable of supplying periodic refrigeration at 10 K. The system is intended to cool a focal plane array for a low-earth orbit satellite. The refrigeration is effected by sublimating solid hydrogen at 10 K. The solid hydrogen is produced in a batch process by cooling, solidifying, and subcooling liquid hydrogen formed at 30 K by a Joule-Thomson expansion. The spent hydrogen from the sublimation and Joule-Thomson expansion is absorbed by two metal hydride sorption bed assemblies.

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.

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.

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.

The Water Processor Assembly (WPA) for use on the International Space Station (ISS) includes various technologies for the treatment of waste water. These technologies include filtration, ion exchange, adsorption, catalytic oxidation, and iodination. The WPA hardware implementing portions of these technologies, including the Particulate Filter, Multifiltration Bed, Ion Exchange Bed, and Microbial Check Valve, was recently qualified for chemical performance at the Marshall Space Flight Center. Waste water representing the quality of that produced on the ISS was generated by test subjects and processed by the WPA. Water quality analysis and instrumentation data was acquired throughout the test to monitor hardware performance. This paper documents operation of the test and the assessment of the hardware performance.

This paper describes the development plan for a comprehensive research and diagnostic tool for aspects of advanced life support systems in space-based laboratories. Specifically, it aims to build a high fidelity tabletop model that can be used for the purpose of risk mitigation, failure mode analysis, contamination tracking, and testing reliability. The work envisions a comprehensive approach involving experimental work coupled with numerical simulation to develop this diagnostic tool. The use of an index matching fluid (fluid that matches the refractive index of cast acrylic, the model material) allows making the entire model (with complex internal geometry) transparent and hence conducive to non-intrusive optical diagnostics. Experimental and modeling work to date will be presented.

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].

An analysis model has been developed for analyzing/optimizing the integration of a carbon dioxide removal assembly (CDRA), CO2 compressor, accumulator, and Sabatier CO2 reduction assembly. The integrated model can be used in optimizing compressor sizes, compressor operation logic, water generation from Sabatier, utilization of CO2 from crew metabolic output, and utilization of H2 from oxygen generation assembly. Tests to validate CO2 desorption, recovery, and compression had been conducted in 2002-2003 using CDRA/Simulation compressor set-up at NASA Marshall Space Flight Center (MSFC). An analysis of test data has validated CO2 desorption rate profile, CO2 compressor performance, CO2 recovery and CO2 vacuum vent in the CDRA model. Analysis / optimization of the compressor size and the compressor operation logic for an integrated closed air revitalization system is currently being conducted