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The development of the Advanced Life Support (ALS) Sizing Analysis Tool (ALSSAT) using Microsoft® Excel was initiated by the Crew and Thermal Systems Division (CTSD) of Johnson Space Center (JSC) in 1997 to support the ALS and Exploration Offices in Environmental Control and Life Support System (ECLSS) design and studies. It aids the user in performing detailed sizing of the ECLSS for different combinations of the ALS regenerative system technologies (1, 2). This analysis tool will assist the user in performing ECLSS preliminary design and trade studies as well as system optimization efficiently and economically.

The development of an optimum regenerative Advanced Life Support (ALS) system for future Mars missions has been a crucial issue in the space industry. Considering the numerous potential technologies for subsystems with the complexity of the Air Revitalization System (ARS), Water Reclamation System (WRS), and Waste Management System of the Environmental Control and Life Support System (ECLSS), it will be time-consuming and costly to determine the best combination of these technologies without a powerful sizing analysis tool. Johnson Space Center (JSC), therefore, initiated the development of ALSSAT using Microsoft® Excel for this purpose. ALSSAT has been developed based upon the ALS Requirement and Design Definition Document (Ref. 18). In 1999, a paper describing the development of ALSSAT with its built-in ARS mass balance model (Ref. 21) was published in ICES.

The existing Shuttle Extravehicular Mobility Unit (EMU) has served NASA well for sometime, however, it uses a large amount of consumables including water, O2 and lithium hydroxide. In order for extended missions to the Moon and Mars to be successful, two new portable life support systems (PLSS) designs have been proposed that will minimize the amount of consumables used and will be more reliable due to simplified designs. This paper considers one such PLSS, currently designated the Cryogenic-PLSS (CPLSS). The reason for this designation is because it uses liquid O2 to provide the breathing gas for the astronaut and to provide backup cooling for the astronaut. In order to understand how the system will function in space and to evaluate final design parameters, a transient thermal model has been developed using the software package MATLAB/Simulink.

A transient model of the Minimum Consumables Portable Life Support System (MPLSS) Advanced Space Suit design has been developed and implemented using MAT-LAB/Simulink. The purpose of the model is to help with sizing and evaluation of the MPLSS design and aid development of an automatic thermal comfort control strategy. The MPLSS model is described, a basic thermal comfort control strategy implemented, and the thermal characteristics of the MPLSS Advanced Space Suit are investigated.

The duration and frequency of extravehicular activity (EVA) is expected to increase with the anticipation of challenging missions ahead. This necessitates the development of an automatic controller for astronaut thermal comfort regulation. A reliable human thermal model is essential in order to predict the thermal response of subjects under various conditions to aid in automatic controller development. This paper examines thermal response sensitivity to several parameters and input modifications using a popular human thermal model. These parameter and input variations are based either on values reported in the literature or realistic estimates.

The NASA JSC Shuttle EMU computer model (SINDA EMU) is presently used to analyze the thermal behavior of the Space Shuttle EMU. This paper uses the SINDA EMU model along with EMU experimental and flight data to investigate and define several performance characteristics of the Space Shuttle EMU related to thermal comfort control.

This paper discusses several issues related to the PLSS thermal model requirements for a planned generalized EVA Simulation Test Bed. The existing models of the extravehicular mobility unit (EMU) are briefly discussed and then the paper focuses specifically on the NASA JSC Shuttle EMU model (referred to as SINDA EMU). After the SINDA EMU model review, the PLSS thermal model requirements for the EVA Simulation Test Bed are discussed in detail.