Search Results

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.

The Spacesuit Water Membrane Evaporator (SWME) is the baseline heat rejection technology selected for development for the Constellation lunar suit. The first SWME prototype, designed, built, and tested at Johnson Space Center in 1999 used a Teflon hydrophobic porous membrane sheet shaped into an annulus to provide cooling to the coolant loop through water evaporation to the vacuum of space. This present study describes the test methodology and planning to compare the test performance of three commercially available hollow fiber materials as alternatives to the sheet membrane prototype for SWME, in particular, a porous hydrophobic polypropylene, and two variants that employ ion exchange through non-porous hydrophilic modified Nafion. Contamination tests will be performed to probe for sensitivities of the candidate SWME elements to ordinary constituents that are expected to be found in the potable water provided by the vehicle, the target feedwater source.

ASDA was developed to evaluate the heat and mass transfer characteristics of advanced pressurized suit design concepts for use in low pressure or vacuum planetary environments. The model incorporates a generalized 3-layer suit, constructed with the Systems Integrated Numerical Differencing Analyzer '85 (SINDA '85), with a 41- node FORTRAN routine that simulates the transient heat transfer and respiratory processes of a human body in a suited environment. User options for the suit include a liquid cooled garment, a removable jacket, a CO2/H2O permeable layer and a phase change layer. The model also has an option to isolate flowing oxygen in the helmet from stagnant or flowing gas in the torso and limbs. Options for the environment include free and forced convection with a user input atmosphere, incident solar/infrared fluxes, radiation to a background sink and radiation and conduction to a surface. Results from a study of Mars suit concepts will also be presented.

A series of hot and cold thermal vacuum tests compared the radiation and contact conduction thermal performance of two Space Shuttle extravehicular pressure suit glove designs. An ambient test established the relationship between heat transfer and contact pressure. Contact with hot and cold objects was tolerated longer with an enhanced fingertip insulation design. The data obtained was used to correlate a glove model for predicting skin temperatures of advanced gloves in extreme extravehicular thermal environments.

A thermoelectric liquid cooling system recently developed at the Johnson Space Center was evaluated in manned and unmanned ground tests as an alternative to the Space Shuttle launch and entry suit personal fan. The liquid cooling system provided superior cooling in environments simulating flight deck conditions during launch and postlanding.