Browse Publications Technical Papers 2007-01-3208
2007-07-09

Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT) for Advanced Spacesuit Systems 2007-01-3208

An effort was initiated by NASA/JSC in 2001 to develop an Extravehicular Activity System Sizing Analysis Tool (EVAS_SAT) for the sizing of Extravehicular Activity System (EVAS) architecture and studies. Its intent was to support space suit development efforts and to aid in conceptual designs for future human exploration missions. Its basis was the Life Support Options Performance Program (LSOPP), a spacesuit and portable life support system (PLSS) sizing program developed for NASA/JSC circa 1990. EVAS_SAT estimates the mass, power, and volume characteristics for user-defined EVAS architectures, including Suit Systems, Airlock Systems, Tools and Translation Aids, and Vehicle Support equipment.
The tool has undergone annual changes and has been updated as new data have become available. Certain sizing algorithms have been developed based on industry standards, while others are based on the LSOPP sizing routines. Because EVAS_SAT was designed for use by members of the EVA community, subsystem familiarity on the part of the intended user group and in the analysis of results is assumed. The current EVAS_SAT is operated within Microsoft Excel 2003 using a Visual Basic interface system.
The EVAS_SAT sizing approach breaks the Extravehicular Activity (EVA) System down into major subsystems (Suit, Airlock, Tools, and Vehicle Equipment) and then breaks the subsystems down into technology-independent functional blocks that become the input categories for each subsystem. Each functional block contains the different technologies that provide that function. Baseline sizing for existing technologies is determined, as well as baseline sizing for new technologies. The baseline value will be used as a default value. If a detailed sizing method is not available for new technologies, the new technology is scaled relative to the default technology.
EVAS_SAT has been used to conduct trade studies of combinations of technologies based on various PLSS schematics proposed by NASA, Oceaneering Space Systems (OSS), and the Texas Engineering Experiment Station (TEES).

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