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During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment, the load from the electrical components and incident radiation. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Radiators have no moving parts and are thus simple and highly reliable. However, past freezable radiators have been too heavy.

This paper details the analysis and design of the Temporary Sleep Station (TeSS) environmental control system for International Space Station (ISS). The TeSS will provide crewmembers with a private and personal space, to accommodate sleeping, donning and doffing of clothing, personal communication and performance of recreational activities. The need for privacy to accommodate these activities requires adequate ventilation inside the TeSS. This study considers whether temperature, carbon dioxide, and humidity remain within crew comfort and safety levels for various expected operating scenarios. Evaluation of these scenarios required the use and integration of various simulation codes. An approach was adapted for this study, whereby results from a particular code were integrated with other codes when necessary.

Procedures that have been developed as part of the NASA JSC-sponsored pre-prototype Checkout, Servicing and Maintenance (COSM) program for pre- and post-EVA airlock operations are described. This paper addresses the accompanying pressure changes in the airlock and in the Advanced Extravehicular Mobility Unit (EMU). Additionally, the paper focuses on the components that are checked out, and includes the step-by-step sequences to be followed by the crew, the required screen displays and prompts that accompany each step, and a description of the automated processes that occur.

As a key component in its ground test bed capability, NASA's Advanced Life Support Program has been developing a large-scale advanced life support facility capable of supporting long-duration testing of integrated bioregenerative life support systems with human test crews. This facility, the Bioregenerative Planetary Life Support Systems Test Complex (BIO-Plex), is currently under development at the Johnson Space Center. The BIO-Plex is comprised of a set of interconnected test chambers with a sealed internal environment capable of supporting test crews of four individuals for periods exceeding one year. The life support systems to be tested will consist of both biological and physicochemical technologies and will perform all required air revitalization, water recovery, biomass production, food processing, solid waste processing, thermal management, and integrated command and control functions.

Approximately 50% of the water consumed by International Space Station crewmembers is water recovered from cabin humidity condensate. Condensing heat exchangers in the Russian Service Module (SM) and the United States On-Orbit Segment (USOS) are used to control cabin humidity levels. In the SM, humidity condensate flows directly from the heat exchanger to a water recovery system. In the USOS, a metal bellows tank located in the US Laboratory Module (LAB) collects and stores condensate, which is periodically off-loaded in about 20-liter batches to Contingency Water Containers (CWCs). The CWCs can then be transferred to the SM and connected to a Condensate Feed Unit that pumps the condensate from the CWCs into the water recovery system for processing. Samples of the condensate in the tank are collected during the off-loads and returned to Earth for analyses.

Scientists and engineers at NASA are currently developing flight instruments which will demonstrate oxygen production on the Moon and Mars. REGA will extract oxygen from the lunar regolith, measure implanted solar wind and indigenous gases, and monitor the lunar atmosphere. MIP will demonstrate oxygen production on Mars, along with key supporting technologies including filtration, atmospheric acquisition and compression, thermal management, solar cell performance, and dust removal.

The Space Shuttle humidity separator prefilter was developed to remove debris from the air/water stream that flows from the cabin condensing heat exchanger to the humidity separator. Debris in this flow stream has caused humidity separator pitot tube clogging and subsequent water carryover on several Shuttle flights. The first design concept of the prefilter was flown on STS-40 in June, 1991. The prefilter was installed on-orbit. Video footage of its operation revealed that the prefilter did not pass water at a constant rate, resulting in a tendency to slug the humidity separator. The results from this flight test have resulted in a complete redesign of the prefilter. In this paper the first prefilter design is described, the flight results from STS-40 are examined, and the on-orbit performance of the prefilter is explained. The redesigned prefilter is described with emphasis on the features that should allow successful reduced gravity operation.

Metabolically produced carbon dioxide (CO2) removal in spacesuit applications has traditionally been accomplished utilizing non-regenerative Lithium Hydroxide (LiOH) canisters. In recent years, regenerative Metal Oxide (MetOx) has been developed to replace the Extravehicular Mobility Unity (EMU) LiOH canister for extravehicular activity (EVA) missions in micro-gravity, however, MetOx may carry a significant weight burden for potential use in future Lunar or planetary EVA exploration missions. Additionally, both of these methods of CO2 removal have a finite capacity sized for the particular mission profile. Metabolically produced water vapor removal in spacesuits has historically been accomplished by a condensing heat exchanger within the ventilation process loop of the suit life support system.

Future NASA manned missions to the moon and Mars will require development of robust regenerative life support system technologies which offer high reliability and minimal resupply. To support the development of such systems, early ground-based test facilities will be required to demonstrate integrated, long-duration performance of candidate regenerative air revitalization, water recovery, and thermal management systems. The advanced life support Systems Integration Research Facility (SIRF) is one such test facility currently being developed at NASA's Johnson Space Center (JSC). The SIRF, when completed, will accommodate unmanned and subsequently manned integrated testing of advanced regenerative life support technologies at ambient and reduced atmospheric pressures.

The Space Shuttle Lightweight Mission Specialist Seat (LWS-MS) is a crew seat used by mission specialists who fly aboard the Space Shuttle. A team of NASA and Lockheed-Martin engineers from the Johnson Space Center (JSC) in Houston, Texas, redesigned the MS seats and reduced the weight of the seats by 52%. In addition to weight reduction, the seats were designed to tolerate stringent load conditions, inspired by new FAA regulations requiring new seats to undergo dynamic testing and floor warping demonstrations. This paper describes the analysis methods used to predict the behavior of the seat. Detailed finite element models, developed using MSC/NASTRAN, and dynamic models using finite element and rigid-body information combined in a program called DADS, were used to accurately characterize the behavior of the seat before testing even began. This analysis technique led to significant weight reductions, as well as safety improvements in the seat.

The Portable Life Support System (PLSS) emergency oxygen system is being reexamined for the next generation of suits. These suits will be used for transit to Low Earth Orbit, the Moon and to Mars as well as on the surface of the Moon and Mars. Currently, the plan is that there will be two different sets of suits, but there is a strong desire for commonality between them for construction purposes. The main purpose of this paper is to evaluate what the emergency PLSS requirements are and how they might best be implemented. Options under consideration are enlarging the tanks on the PLSS, finding an alternate method of storage/delivery, or providing additional O2 from an external source. The system that shows the most promise is the cryogenic oxygen system with a composite dewar which uses a buddy system to split the necessary oxygen between two astronauts.

An evaporative heat sink has been designed and built by AlliedSignal for NASA's Johnson Space Center. The unit is a demonstrator of a primary heat exchanger for NASA's prototype Crew Return Vehicle (CRV), designated the X-38. The primary heat exchanger is responsible for rejecting the heat produced by both the flight crew and the avionics. Spacecraft evaporative heat sinks utilize space vacuum as a resource to control the vapor pressure of a liquid. For the X-38, water has been chosen as the heat transport fluid. A portion of this coolant flow is bled off for use as the evaporant. At sufficiently low pressures, the water can be made to boil at temperatures approaching its freezing point. Heat transferred to liquid water in this state will cause the liquid to evaporate, thus creating a heat sink for the spacecraft's coolant loop. The CRV mission requires the heat exchanger to be compact and low in mass.

Shortly after installation of the service and performance heat exchanger (SPCU HX) in 2001, samples collected from the coolant fluid indicated the presence of nickel accompanied by a subsequent decrease in phosphate concentration along with a high microbial load. When the SPCU HX was replaced and evaluated post-flight, it was expected that the heat exchanger would have significant biofilm and corrosion present given the composition of the coolant fluid; however, there was no evidence of either. Early results from two experiments imply that the heat exchanger materials themselves are inhibiting biofilm formation. This paper discusses the results of one set of experiments and puts forward the inhibition of quorum sensing as a possible mechanism for the lack of biofilm formation.

A system performance study on a portable life support system being developed for use in the Weightless Environment Training Facility (WETF) and the Neutral Buoyancy Laboratory (NBL) has been completed. The Neutral Buoyancy Portable Life Support System (NBPLSS) will provide life support to suited astronauts training for extravehicular activity (EVA) under water without the use of umbilicals. The basic configuration is characterized by the use of medium pressure (200 - 300 psi) cryogen (liquid nitrogen/oxygen mixture) which provides cooling within the Extravehicular Mobility Unit (EMU), the momentum which enables flow in the vent loop, and oxygen for breathing. NBPLSS performance was analyzed by using a modified Metabolic Man program to compare competing configurations. Maximum sustainable steady state metabolic rates and transient performance based on a typical WETF metabolic rate profile were determined and compared.

NASA's Constellation Program includes the Orion, Altair, and Lunar Surface Systems (LSS) project offices. The first two elements, Orion and Altair, are manned space vehicles while the third element is broader and includes several subelements including Rovers and a Lunar Habitat. The upcoming planned missions involving these systems and vehicles include several risks and design challenges. Due to the unique thermal environment, many of these risks and challenges are associated with the vehicles' thermal control system. NASA's Exploration Systems Mission Directorate (ESMD) includes the Exploration Technology Development Program (ETDP). ETDP consists of several technology development projects. The project chartered with mitigating the aforementioned risks and design challenges is the Thermal Control System Development for Exploration Project.

During extravehicular activities (EVAs) it is crucial to keep the astronaut comfortable. Currently, a sublimator rejects to space both the astronaut's metabolic heat and that produced by the Portable Life Support System. In doing so, it consumes up to 3.6 kg (8 lbm) of water; the single largest expendable during an eight-hour EVA. While acceptable for low earth orbit, resupply for moon and interplanetary missions will be too costly. Fortunately, the amount of water consumed can be greatly reduced if most of the heat load is radiated to space. However, the radiator must reject heat at the same rate that it is generated to prevent heat stroke or frostbite. Herein, we report on a freezable radiator and heat exchanger to proportionally control the heat rejection rate.

NASA's Advanced Life Support Program has included as part of its long-range planning the development of a large-scale advanced life support facility capable of supporting long-duration testing of integrated, regenerative biological and physicochemical life support systems. As the designated NASA Field Center responsible for integration and testing of advanced life support systems, Johnson Space Center has undertaken the development of such a facility--the Advanced Life Support Human-Rated Test Facility (HRTF). As conceived, the HRTF is an interconnected five-chamber facility with a sealed internal environment capable of supporting a test crew of four for periods exceeding one year. The life support system which sustains the crew consists of both biological and physicochemical components and will perform air revitalization, water recovery, food production, solid waste processing, thermal management, and integrated control and monitoring functions.

Automatic thermal comfort control for the minimum consumables PLSS is undertaken using several control approaches. Accuracy and performance of the strategies using feedforward, feedback, and gain scheduling are evaluated through simulation, highlighting their advantages and limitations. Implementation issues, consumable usage, and the provision for the extension of these control strategies to the cryogenic PLSS are addressed.

Debris in the Orbiter crew compartment of early Shuttle missions created crew health concerns and physiological discomfort, and was the cause of some equipment malfunctions. Debris from Orbiters during flight and processing was analyzed, quantized, and evaluated to determine its source. Records were kept on the amount of debris vacuumed by the crew during on-orbit cleaning and the amount found on air-cooled avionics boxes during ground turnaround. After ground turnaround operations at Kennedy Space Center and Palmdale were reviewed from a facility, materials use, and materials control standpoint, the following remedial steps were taken.

During an ExtraVehicular Activity (EVA), both the heat generated by the astronaut's metabolism and that produced by the Portable Life Support System (PLSS) must be rejected to space. The heat sources include the heat of adsorption of metabolic CO2, the heat of condensation of water, the heat removed from the body by the liquid cooling garment and the load from the electrical components. Although the sublimator hardware to reject this load weighs only 1.58 kg (3.48 lbm), an additional 3.6 kg (8 lbm) of water are loaded into the unit, most of which is sublimated and lost to space, thus becoming the single largest expendable during an eight-hour EVA. Using a radiator to reject heat from the astronaut during an EVA can reduce the amount of expendable water consumed in the sublimator. Last year we reported on the design and initial operational assessment tests of a novel radiator designated the Radiator And Freeze Tolerant heat eXchanger (RAFT-X).