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Future space exploration missions will require a lightweight spacesuit that expends no consumables. This paper describes the design and performance of a prototype heat rejection system that weighs less than current systems and vents zero water. The system uses regenerable LiCl/water absorption cooling. Absorption cooling boosts the heat absorbed from the crew member to a high temperature for rejection to space from a compact, non-venting radiator. The system is regenerated by heating to 100°C for two hours. The system provides refrigeration at 17°C and rejects heat at temperatures greater than 50°C. The overall cooling capacity is over 100 W-hr/kg.

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.

A new life support approach is proposed for use on the International Space Station (ISS). This involves advanced technologies for water recovery and air revitalization, tested at the Johnson Space Center (JSC), including bioprocessing, reverse-osmosis and distillation, low power carbon dioxide removal, non-expendable trace contaminant control, and carbon dioxide reduction.

An Advanced Automotive Manikin (ADAM), is used to evaluate liquid cooling garments (LCG) for advanced space suits for extravehicular applications and launch and entry suits. The manikin is controlled by a finite-element physiological model of the human thermoregulatory system. ADAM's thermal response to a baseline LCG was measured.The local effectiveness of the LCG was determined. These new thermal comfort tools permit detailed, repeatable measurements and evaluation of LCGs. Results can extend to other personal protective clothing including HAZMAT suits, nuclear/biological/ chemical protective suits, fire protection suits, etc.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on applicable air-quality standards, measurements of pollutant concentrations, and crew reports of air quality. Samples of air were obtained during ingress and egress of the Zarya and Unity modules on missions 2A and 2A.1. The results from 2A suggest that trace pollutants were at safe levels and that there was good air exchange between the modules. Results from the 2A.1 flight also showed that trace pollutants were at acceptable concentrations; however, there was evidence of inadequate mixing between the modules during the hatch-open operations. Furthermore, the 2A.1 crew reported after the flight that the air quality seemed to cause symptoms during their operations in Zarya, particularly when more than one crewmember was working inside open panels for some time.

Space-faring crews must have safe breathing air throughout their missions to ensure adequate performance and good health. Toxicological assessment of air quality depends on the standards that define acceptable air quality, measurements of pollutant levels during the flight, and reports from the crew on their in-flight perceptions of air quality. Air samples returned from ISS on flights 8A, UF2, 9A, and 11A were analyzed for trace pollutants. On average, the air during this period of operations was safe for human respiration. However, about 3 hours into the regeneration of 2 Metox canisters in the U.S. airlock on 20 February 2002 the crew reported an intolerable odor that caused them to stop the regeneration, take refuge in the Russian segment, and scrub air in the U.S. segment for 30 hours. Analytical data from grab samples taken during the incident showed that the pollutants released were characteristic of nominal air pollutants, but were present in much higher concentrations.

There are many sources of air pollution that can threaten air quality during space missions. The International Space Station (ISS) is an extremely complex platform that depends on a multi-tiered strategy to control the risk of excessive air pollution. During the seven missions surveyed by this report, the ISS atmosphere was in a safe, steady-state condition; however, there were minor loads added as new modules were attached. There was a series of leaks of octafluoropropane, which is not directly toxic to humans, but did cause changes in air purification operations that disrupted the steady state condition. In addition, off-nominal regeneration of metal oxide canisters used during extravehicular activity caused a serious pollution incident.

Flexible fiber-reinforced aerogel composites were studied for use as insulation materials of a future space suit for Moon and Mars exploration. High flexibility and good thermal insulation properties of fiber-reinforced silica aerogel composites at both high and low vacuum conditions make it a promising insulation candidate for the space suit application. This paper first presents the results of a durability (mechanical cycling) study of these aerogels composites in the context of retaining their thermal performance. The study shows that some of these Aerogels materials retained most of their insulation performance after up to 250,000 cycles of mechanical flex cycling. This paper also examines the problem of integrating these flexible aerogel composites into the current space suit elements.

For planetary exploration, new thermal insulation materials are needed to deal with unique environmental conditions presented to extravehicular activity (EVA). The thermal insulation material and system used in the existing space suit were specifically designed for low orbit environment. They are not adequate for low vacuum condition commonly found in planetary environments with a gas atmosphere. This study attempts to identify the types of lofty nonwoven thermal insulation materials and the construction parameters that yield the best performance for such application. Lofty nonwovens with different construction parameters are evaluated for their thermal conductivity performance. Three different types of fiber material: solid round fiber, hollow fiber, and grooved fiber, with various denier, needling intensity, and web density were evaluated.

This paper presents the analysis findings of a study reducing the overall mass of the lightweight liquid cooling garment (LCG). The LCG is a garment worn by crew to actively cool the body, for spacesuits and launch/entry suits. A mass reduction of 66% was desired for advanced missions. A thermal math model of the LCG was developed to predict its performance when various mass-reducing changes were implemented. Changes included varying the thermal conductivity and thickness of the garment or of the coolant tubes servicing the garment. A second model was developed to predict behavior of the suit when the cooling tubes were to be removed, and replaced with a highly-conducting (waterless) material. Findings are presented that show significant reductions in weight are theoretically possible by improving conductivity in the garment material.

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.

There is a possibility that trace contaminants in the Shuttle Orbiter cabin atmosphere may chemically react with amine beads found in the Regenerative Carbon Dioxide Removal System and degrade system performance. Two contaminant compounds were exposed to the amine beads, and performance changes were measured. Acetone was tested because it is sometimes found in small but appreciable quantities in the cabin, and it has chemical properties that make it a potential poison. Halon 1301 was tested because it is the fire extinguishant, and a discharge of a Halon canister would trigger high concentrations in the cabin. Acetone was shown to be weakly and reversibly adsorbed. It does not poison the bed, and the RCRS was shown to remove small quantities of acetone. Halon was shown to be inert to the amine. It does not poison the RCRS, and is not removed by the RCRS.

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.

Metabolic heat regenerated temperature swing adsorption (MTSA) technology is being developed for removal and rejection of carbon dioxide (CO2) and heat from a portable life support system (PLSS) to the Martian environment. Previously, hardware was built and tested to demonstrate using heat from simulated, dry ventilation loop gas to affect the temperature swing required to regenerate an adsorbent used for CO2 removal. New testing has been performed using a moist, simulated ventilation loop gas to demonstrate the effects of water condensing and freezing in the heat exchanger during adsorbent regeneration. Also, the impact of MTSA on PLSS design was evaluated by performing thermal balances assuming a specific PLSS architecture. Results using NASA's Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT), a PLSS system evaluation tool, are presented.

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.

In a crewed spacecraft environment, atmospheric carbon dioxide (CO2) and moisture control are crucial. Hamilton Sundstrand has developed a stable and efficient amine-based CO2 and water vapor sorbent, SA9T, that is well suited for use in a spacecraft environment. The sorbent is efficiently packaged in pressure-swing regenerable beds that are thermally linked to improve removal efficiency and minimize vehicle thermal loads. Flows are all controlled with a single spool valve. This technology has been baselined for the new Orion spacecraft. However, more data was needed on the operational characteristics of the package in a simulated spacecraft environment. A unit was therefore tested with simulated metabolic loads in a closed chamber at Johnson Space Center during the last third of 2006. Tests were run at a variety of cabin temperatures and with a range of operating conditions varying cycle time, vacuum pressure, air flow rate, and crew activity levels.

Research committed by the Langley Research Center through 1995 resulting in the HZETRN code provides the current basis for shield design methods according to NASA STD-3000 (2005). With this new prominence, the database, basic numerical procedures, and algorithms are being re-examined with new methods of verification and validation being implemented to capture a well defined algorithm for engineering design processes to be used in this early development phase of the Bush initiative. This process provides the methodology to transform the 1995 HZETRN research code into the 2005 HZETRN engineering code to be available for these early design processes. In this paper, we will review the basic derivations including new corrections to the codes to insure improved numerical stability and provide benchmarks for code verification.

Meeting radiation protection requirements during EVA is predominantly an operational issue with some potential considerations for temporary shelter. The issue of spacesuit shielding is mainly guided by the potential of accidental exposure when operational and temporary shelter considerations fail to maintain exposures within operational limits. In this case, very high exposure levels are possible which could result in observable health effects and even be life threatening. Under these assumptions, potential spacesuit radiation exposures have been studied using known historical solar particle events to gain insight on the usefulness of modification of spacesuit design in which the control of skin exposure is a critical design issue and reduction of blood forming organ exposure is desirable.

Major improvements have recently been completed in the approach to spacecraft shielding analysis. A Computer-Aided Design (CAD)-based system has been developed for determining the shielding provided to any point within or external to the spacecraft. Shielding analysis is performed using a commercially available stand-alone CAD system and a customized ray-tracing subroutine contained within a standard engineering modeling software package. This improved shielding analysis technique has been used in several vehicle design projects such as a Mars transfer habitat, pressurized lunar rover, and the redesigned Space Station. Results of these analyses are provided to demonstrate the applicability and versatility of the system.