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Technical Paper

Lunar EVA Thermal Environment Challenges

2006-07-17
2006-01-2231
With new direction to return to the Moon, NASA is developing highly efficient and lightweight extravehicular activity (EVA) equipment for working on the rugged lunar terrain. This paper presents results and evaluations of lunar thermal environments and design challenges for the EVA system. The evaluations include a review of basic lunar environment data, a review of metabolic rate predictions, analyses and reviews of spacesuit heat leak effects in past designs, and methods to improve the performance of spacesuit-mounted radiators in a hot lunar environment. In addition to reviewing existing lunar thermal environment data, a simplified thermal model is presented that can simulate the lunar surface temperature variation as a function of latitude and time on the lunar surface. The assumed physical and optical properties of the lunar soil as well as the solar heating on the Earth's Moon are also presented.
Technical Paper

Space Shuttle Launch Entry Suit Thermal Performance Evaluation

1993-07-01
932297
Comments of the Space Shuttle crew indicate that the Launch Entry Suit (LES) may provide inadequate cooling before launch and after reentry. During these periods some crewmembers experienced thermal discomfort induced by localized cabin heating, middeck experiments, and crewmembers' body heat and humidity. The NASA Johnson Space Center(JSC) Crew and Thermal System Division (CTSD) executed a two phase study, analysis and testing, to investigate this problem. The analysis phase used a computer model of the LES to study the transient heat dissipation and temperature response under the various Space Shuttle flight cabin environments. After the completion of the analysis, the testing phase was conducted to collect the engineering data in order to validate the analysis results. Due to the constraint of the test facility, the test was conducted on the air cooled techniques only. This paper presents the analytical model, its solution and an evaluation and summary of the test results.
Technical Paper

First Lunar Outpost Extravehicular Life Support System Evaluation

1993-07-01
932188
A preliminary evaluation of several portable life support system (PLSS) concepts which could be used during the First Lunar Outpost (FLO) mission extravehicular activities (EVA's) has been performed. The weight, volume and consumables characteristics for the various PLSS concepts were estimated. Thermal effects of day and night EVA's on PLSS consumables usage and hardware requirements were evaluated. The benefit of adding a radiator and the total PLSS weight to be carried by the astronaut were also evaluated for each of the concepts. The results of the evaluation were used to provide baseline weight, volume and consumables characteristics of the PLSS to be used on the 45 day FLO mission. The benefit of radiators was shown to be substantial. Considerable consumables savings were predicted for EVA schedules with a high concentration of nighttime EVA's versus daytime EVA's.
Technical Paper

ASDA - Advanced Suit Design Analyzer Computer Program

1992-07-01
921381
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.
Technical Paper

Shuttle EMU 4000 Series and 4750 Series Glove Thermal Performance

1995-07-01
951548
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.
Technical Paper

Shuttle Launch Entry Suit Liquid Cooling System Thermal Performance

1995-07-01
951546
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.
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