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The Advanced Integration Matrix (AIM) Project will investigate systems integration and test for the Vision for Space Exploration. The goal of AIM is to reduce the risk of future human missions by identifying those significant risks that Earth-based integration and test can reduce. AIM will focus on the mission requirements that need verification beyond component/subsystem testing, but that can still be tested on Earth. In order to help set priorities for AIM, this paper describes a preliminary Probabilistic Risk Analysis (PRA) framework that was developed based on the Vision for Space Exploration. The PRA provides a decision-making tool to balance mission risk, performance, and cost.

A regenerable carbon dioxide (CO2) removal system has been certified for use with the Extravehicular Mobility Unit (EMU), or space suit. The new system, nicknamed “Metox” to reflect its use of metal-oxide as the CO2 sor-bent material, was designed and developed by Hamilton Standard Space Systems International (HSSSI), Inc., under contract1 to the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC). As a part of the certification process, one hundred (100) operating cycles were accumulated on the certification canister and sixteen (16) regeneration cycles on the certification regenerator. This paper presents a summary of those tests. The results characterize canister performance for a wide range of temperatures, pressures and metabolic rates. It also presents regenerator performance under nominal and worst case operating conditions.

The importance of being able to determine the usage rate of life support subsystem consumables was recognized well before the first Apollo Extravehicular Activity (EVA). Since that time, metabolic activity levels have been evaluated and recorded for each EVA crew member. Throughout the history of the United States space program, EVA metabolic rates have been shown to be variable depending upon the mission scenario and the equipment used. Knowing this historic information is invaluable for current EVA planning activities, as well as for the design of future Extravehicular Mobility Unit (EMU) systems. This paper presents an overview of historic metabolic expenditures for Apollo, Skylab, and Shuttle missions, along with a discussion of the types of EVA crew member activities which lead to various metabolic rate levels, and a discussion on how this data is being used to develop advanced EMU systems.

The device described in this paper is a flat sheet membrane module that removes humidity from the space suit breathing loop by venting it to the vacuum of space. The module consists of alternating vacuum layer assemblies and vent layer assemblies separated by solid polymer membrane sheets. The module is designed to optimize volume and pressure drop at a given vent flow rate and water removal rate. Both Hamilton Standard and the NASA Johnson Space Center tested the module under varying EMU flow and humidity conditions; the results of the testing are presented in the paper. The module met or exceeded all of the design goals set forth in the program statement of work, including volume, pressure drop and water removal rate.

Hamilton Standard Space Systems International, Inc. is currently under contract to NASA for the development and certification of an advanced technology regenerable carbon dioxide removal system for the International Space Station Extravehicular Mobility Unit (EMU), or “space suit.” This new metal-oxide-based system (“Metox”) will replace the existing non-regenerable lithium hydroxide (LiOH) carbon dioxide (CO2) removal system located in the EMU's Primary Life Support System (PLSS). The Metox canister is designed to replace the current LiOH Contamination Control Canister (CCC) with no modification to existing EMU interfaces. The metal oxide sorbent is “regenerable” and can be restored to its original condition permitting the Metox canisters to be used over and over again on-orbit. Once a Metox canister becomes “loaded” with CO2, it will be placed in the “Regenerator,” where the system will circulate hot air through the canister to drive off, or desorb, the CO2.

The NASA Shuttle Extravehicular Mobility Unit (EMU) uses a non-regenerable absorbent to remove CO2 from an astronaut's breathing loop. A savings in launch weight, storage volume and life cycle cost may be achieved by incorporating a regenerable CO2 removal system into the EMU. This paper will discuss regenerable CO2 sorbents and their impact on the life support system of an EMU. The systems evaluated will be judged on their technical maturity, impact to the EMU, and impacts to space station and shuttle operation

Developing advanced technology through the prototype phase on a system as complex as a Portable Life Support Subsystem (PLSS) for an Extravehicular Mobility Unit (EMU) is a time and resource consuming process. Experience has shown that most of the decisions controlling the life cycle cost of a system intended for operational use are made very early in the design process. By the preliminary design review most of the design-controlled cost drivers are locked into the design. To ensure a reasonable chance for the design to successfully meet mission requirements, it is best to choose the most promising, most likely-to-succeed technology available in the early stages of breadboard and preprototype development.

An Extravehicular Mobility Unit (EMU) Portable Life Support Subsystem (PLSS) has among its primary functions requirements to remove metabolically generated heat and respiratory byproducts to maintain an atmosphere which is both physiologically safe and comfortable for the Extravehicular Activity (EVA) crew person. The EMU thermal control system interacts with the crew member through the Liquid Cooling and Ventilation Garment (LCVG), which circulates the ventilation gas to remove carbon dioxide, humidity, and trace contaminants, and the cooling water to remove metabolically produced heat. To maintain thermal comfort, the crew member may vary the LCVG inlet water temperature. The thermal interaction between the EMU and the crew member is very complex and highly dependent upon the individual crew member's cooling preferences and the exterior environment.

Selection of advanced technologies for an evolutionary Space Station Freedom or a planetary (lunar or Martian) extravehicular mobility unit (EMU) will be strongly driven by the system volume and weight, among other factors such as life cycle costs, reliability, safety, etc. A packaging factor will be used to estimate the volume and weight of future EMUs for which the individual component volumes and weights can be determined (by breadboard and preprototype development) but for which the final configurations are not yet known. The purpose of this study is to determine volume and weight packaging factors to be used for sizing trade studies of advanced development Portable Life Support Subsystem (PLSSs). Packaging factors should be based on similar operational systems, e.g., Apollo and Shuttle PLSSs. This paper reports the results of packaging factor studies of both the Apollo EMU PLSS and the National Space Transportation System (NSTS) EMU PLSS.