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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.

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.

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.

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.

In order to reduce the condensation in the Space Station Freedom module, the design of its surface and/or the meteoroid protection shield surface requires special coating to raise the surface temperature while on orbit. This raises a concern of whether the Extravehicular Mobility Unit (EMU) glove will be able to protect the crew member during the Extravehicular Activity (EVA) when the crew member touches the hot or cold surface. EMU gloves provide protection to crew members' hands from a hot or cold touch temperature during an EVA when grasping or touching an object. These gloves also provide protection to crew members in extreme thermal environments. A glove thermal model with the most up-to-date configuration information was developed and utilized to predict reliable touch temperature limits. The analyses performed evaluated several worst case scenarios of both hot and cold environments and object temperatures.

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.

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.

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.