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In order to provide effective cooling for astronauts during extravehicular activities (EVAs), a liquid cooling and ventilation garment (LCVG) is used to remove heat by a series of tubes through which cooling water is circulated. To better predict the effectiveness of the LCVG and determine possible modifications to improve performance, computer simulations dealing with the interaction of the cooling garment with the human body have been run using the Wissler Human Thermal Model. Simulations have been conducted to predict the heat removal rate for various liquid cooled garment configurations. The current LCVG uses 48 cooling tubes woven into a fabric with cooling water flowing through the tubes. The purpose of the current project is to decrease the overall weight of the LCVG system. In order to achieve this weight reduction, advances in the garment heat removal rates need to be obtained.

Spacecraft radiators reject heat to their surroundings. Radiators can be deployable or mounted on the body of the spacecraft. NASA's Crew Exploration Vehicle is to use body mounted radiators. Coatings play an important role in heat rejection. The coatings provide the radiator surface with the desired optical properties of low solar absorptance and high infrared emittance. These specialized surfaces are applied to the radiator panel in a number of ways, including conventional spraying, plasma spraying, or as an appliqué. Not specifically designed for a weathering environment, little is known about the durability of conventional paints, coatings, and appliqués upon exposure to weathering and subsequent exposure to solar wind and ultraviolet radiation exposure. In addition to maintaining their desired optical properties, the coatings must also continue to adhere to the underlying radiator panel.

The Waste and Hygiene Compartment will serve as the primary facility for metabolic waste management and personal hygiene on the United States segment of the International Space Station. The Compartment encloses the volume of two standard ISS racks and will be installed into Node 3 after launch inside a Multipurpose Logistics Module on the Space Shuttle. Long duration space flight requires a departure from the established hygiene and waste disposal practices employed on the Space Shuttle. This paper describes requirements and a conceptual design for the Waste and Hygiene Compartment that are both logistically practical and acceptable to the crew.

Air flow through the passages of a Chrysler LH platform ventilated brake rotor is measured. Modifications to the production rotor's vent inlet geometry are prototyped and measured in addition to the production rotor. Vent passage air flow is compared to existing correlations. The inlet modifications show significantly improved vent air flow, over the production rotor. The result improvement in heat transfer and rotor cooling is reported. These benefits in performance should be attainable at very low increases in production cost.

The US Army uses a light tactical High-Mobility Multi-Purpose Wheeled Vehicle (HMMWV) which, due to the amount of armor added, requires air conditioning to keep its occupants comfortable. The current system uses R134a in a dual evaporator, remote-mounted condenser, engine-driven compressor system. This vehicle has been adapted to use an environmentally friendly refrigerant (carbon dioxide) to provide performance, efficiency, comfort and logistical benefits to the Army. The unusual thermal heat management issues and the fact that the vehicle is required to operate under extreme ambient conditions have made the project extremely challenging. This paper is a continuation of work presented at the SAE Alternate Refrigerants Symposium held in Phoenix last June [1].

A thermal analysis of the compressible carbon dioxide (CO2) flow for the Portable Fire Extinguisher (PFE) system has been performed. A SINDA/FLUINT model has been developed for this analysis. The model includes the PFE tank and the Temporary Sleep Station (TeSS) nozzle, and both have an initial temperature of 72 °F. In order to investigate the thermal effect on the nozzle due to discharging CO2, the PFE TeSS nozzle pipe has been divided into three segments. This model also includes heat transfer predictions for PFE tank inner and outer wall surfaces. The simulation results show that the CO2 discharge rates and component wall temperatures fall within the requirements for the PFE system. The simulation results also indicate that after 50 seconds, the remaining CO2 in the tank may be near the triple point (gas, liquid and solid) state and, therefore, restricts the flow.

The International Space Station (ISS) Active Thermal Control System (ATCS) (Ref. 1,2) has changed over the past several years to address problems and to improve its assembly and operation on-orbit. This paper captures the ways in which the Internal (I) ATCS and External (E) ATCS have changed design characteristics and operations both for the system currently operating on-orbit and the new elements of the system that are about to be added and/or activated. The rationale for changes in ATCS design, assembly and operation will provide insights into the lessons learned during ATCS development. The state of the assembly of the integrated ATCS will be presented to provide a status of the build-up of the system. The capabilities of the on-orbit system will be presented with a summary of the elements of the ISS ATCS that are functional on-orbit plus the plans for launch of remaining parts of the integrated ISS ATCS.

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.

For over 40 years, NASA has been putting humans safely into space in part by minimizing microbial risks to crew members. Success of the program to minimize such risks has resulted from a combination of engineering and design controls as well as active monitoring of the crew, food, water, hardware, and spacecraft interior. The evolution of engineering and design controls is exemplified by the implementation of HEPA filters for air treatment, antimicrobial surface materials, and the disinfection regimen currently used on board the International Space Station. Data from spaceflight missions confirm the effectiveness of current measures; however, fluctuations in microbial concentrations and trends in contamination events suggest the need for continued diligence in monitoring and evaluation as well as further improvements in engineering systems. The knowledge of microbial controls and monitoring from assessments of past missions will be critical in driving the design of future spacecraft.

Research into increased capacity solid amine sorbents has found a candidate (SA9T) that will provide enough increase in cyclic carbon dioxide removal capacity to produce a fully redundant Regenerative Carbon Dioxide Removal System (RCRS). This system will eliminate the need for large quantities of backup LiOH, thus gaining critical storage space on board the shuttle orbiter. This new sorbent has shown an ability to package two fully redundant (four) sorbent beds together with their respective valves, fans and plumbing to create two operationally independent systems. The increase in CO2 removal capacity of the new sorbent will allow these two systems to fit within the envelope presently used by the RCRS. This paper reports on the sub-scale amine testing performed in support of the development effort. In addition, this paper will provide a preliminary design schematic of a fully redundant RCRS.

Long-duration missions in space will require regenerative air revitalization processes. Human testing of these regenerative processes is necessary to provide focus to the system development process and to provide realistic metabolic and hygiene inputs. To this end, the Lyndon B. Johnson Space Center (JSC), under the sponsorship of NASA Headquarters Office of Life and Microgravity Sciences and Applications, is implementing an Early Human Testing (EHT) Project. As part of this project, an integrated physicochemical Air Revitalization System (ARS) is being developed and tested in JSC's Life Support Systems Integration Facility (LSSIF). The components of the ARS include a Four-Bed Molecular Sieve (4BMS) Subsystem for carbon dioxide (CO2) removal, a Sabatier CO2 Reduction Subsystem (CRS), and a Solid Polymer Electrolyte (SPE)™ Oxygen Generation Subsystem (OGS). A Trace Contaminant Control Subsystem (TCCS) will be incorporated at a later date.

The Sublimator Driven Coldplate (SDC) is a unique piece of thermal control hardware that has several advantages over a more traditional thermal control system. The principal advantage is the possible elimination of a pumped fluid loop, potentially saving mass, power, and complexity. Because this concept relies on evaporative heat rejection techniques, it is primarily useful for short mission durations. Additionally, the concept requires a conductive path between the heat-generating component and the heat rejection device. Therefore, it is mostly a relevant solution for a vehicle with a relatively low heat rejection requirement and/or short transport distances. Tests were performed on coupons and an Engineering Development Unit (EDU) at NASA's Johnson Space Center to better understand the basic operational principles and to validate the analytical methods being used for the SDC development.

This paper presents system identification methods of using both frequency and time domain analyses to estimate system parameters for a nonlinear electrohydraulic (E/H) tractor steering system. The frequency domain method identified parameters of the system using a linear model with a nonlinear gain function. The time domain method identified those parameters using a discrete time expression. A method of multiple models was used to represent the nonlinear system for both frequency and time domain analyses. Simulation and test results showed that the modified identification method could satisfactorily identify the parameters of the nonlinear E/H tractor steering system.

Automotive software complexity has been growing rapidly with time. The demand for automation in automotive segment including autonomous automobiles and software based products has caught the attention of researchers. Hence, it is necessary to check the complexity of automotive software and their reliability growth. Testing in the field of software artifact is resource intensive exercise. If project managers are able to put forward testing activities well then the testing resource consumptions may be much more resource/cost efficient. Reliability can be estimated during testing phase of software using software reliability growth models (SRGMs). A software package Computer Aided Software Reliability Estimation (CASRE) has many important SRGMs. These SRGMs are based on Non-Homogeneous Poisson Process (NHPP), Markov process or Bayesian models.

A key component of an Advanced Life Support (ALS) system is the solid waste handling system. One of the most important data sets for determining what solid waste handling technologies are needed is a solid waste model. A preliminary solid waste model based on a six-person crew was developed prior to the 2000 Solid Waste Processing and Resource Recovery (SWPRR) workshop. After the workshop, comments from the ALS community helped refine the model. Refinements included better estimates of both inedible plant biomass and packaging materials. Estimates for Extravehicular Mobility Unit (EMU) waste, water processor brine solution, as well as the water contents for various solid wastes were included in the model refinement efforts. The wastes were re-categorized and the dry wastes were separated from wet wastes. This paper details the revised model as of the end of 2001. The packaging materials, as well as the biomass wastes, vary significantly between different proposed Mars missions.

Two crops of lettuce (Lactuca sativa cv. Waldmann's Green) were grown in the Regenerative Life Support Systems (RLSS) Test Bed at NASA's Johnson Space Center. The RLSS Test Bed is an atmospherically closed, controlled environment facility for the evaluation of regenerative life support systems using higher plants. The chamber encloses 10.6 m2 of growth area under cool-white fluorescent lamps. Lettuce was double seeded in 480 pots, each containing about 250 cm3 of calcined-clay substrate. Each pot was irrigated with half-strength Hoagland's nutrient solution at an average total applied amount of 2.5 and 1.8 liters pot-1, respectively, over each of the two 30-day crop tests. Average environmental and cultural conditions during both tests were 23°C air temperature, 72% relative humidity, 1000 ppm carbon dioxide (CO2), 16h light/8h dark photoperiod, and 356 μmol m-2s-1 photosynthetic photon flux.

Reductions of noise in vehicle passenger compartments in recent years have made some previously undetectable noises audible. Expansion devices used in automobile air conditioning systems are known producers of noise. The fact that these devices are mounted very close to the passengers increases the problems associated with the reduction of this noise. The understanding of the propagation mechanisms from the noise generated in the refrigerant by the expansion device, through the tube and evaporator walls, and finally to the outside air is important. This paper will focus on how noise from expansion devices is transmitted through tube walls downstream of the expansion valve.

This paper presents the study of refrigerant charge imbalance between A/C (cooling) mode and HP (heating) mode of a mobile reversible system. Sensitivities of cooling and heating capacity and energy efficiency with respect to refrigerant charge were investigated. Optimum refrigerant charge level for A/C mode was found to be larger than that for HP mode, primarily due to larger condenser size in A/C mode. Refrigerant charge retention in components at both modes were measured in the lab by quick close valve method. Modeling of charge retention in heat exchangers was compared to experimental measurements. Effect of charge imbalance on oil circulation was also discussed.

When a permanent human outpost is established on the Moon, various methods may be used to reject the heat generated by the base. One proposed concept is the use of a heat pump operating with a vertical, flow-through thermal radiator mounted on a Space Station type habitation module [1]. Since the temperature of the lunar surface varies over the day, the vertical radiator sink temperatures can reach much higher levels than the comfort and even survivability requirements of a habitation module. A high temperature lift heat pump will not only maintain a comfortable habitation module temperature, but will also decrease the size of the radiators needed to reject the waste heat. Thus, the heat pump will also decrease the mass of the entire thermal system. Engineers at the Johnson Space Center (JSC) have tested a High Lift Heat Pump design and are developing the next generation heat pump based on information and experience gained from this testing.

Since the early 1980’s, the Shuttle Extra Vehicular Activity (EVA) glove design has evolved to meet the challenge of space based tasks. These tasks have typically been satellite retrieval and repair or EVA based flight experiments. With the start of the International Space Station (ISS) assembly, the number of EVA based missions is increasing far beyond what has been required in the past; this has commonly been referred to as the “Wall of EVA’s”. To meet this challenge, it was determined that the evolution of the current glove design would not meet future mission objectives. Instead, a revolution in glove design was needed to create a high performance tool that would effectively increase crewmember mission efficiency. The results of this effort have led to the design, certification and implementation of the Phase VI EVA glove into the Shuttle flight program.