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This paper discusses the current state of technology in reduced gravity fire suppression. The focus is on the unique issues associated with the CEV and future spacecraft including operation in reduced gravity and enriched oxygen ambients. Inert gas agents such as carbon dioxide, nitrogen and helium have different minimum extinguishing concentrations (MEC) in microgravity compared to normal gravity; in most instances the MEC in microgravity being higher than in normal gravity. This means that designs based on terrestrial standards will not offer the same factor of safety in microgravity. The results also show that the MEC is a strong function of ambient oxygen concentration in reduced gravity (as expected).

This paper presents a new portable metabolic device (PUMA-Portable Unit for Metabolic Analysis) developed at the NASA Glenn Research Center. PUMA is a battery-operated, wearable unit to measure metabolic rate (minute ventilation, oxygen up-take, carbon dioxide output and heart rate) in a clinical setting, in the field or in remote, extreme environments. The critical sensors in PUMA are located close to the mouth and sampled at 10 Hz to allow intra-breath measurements. PUMA transmits metabolic data wirelessly to a remote computer for data analysis and storage. In addition to it's primary function as a portable metabolic measurement device, the PUMA sensors can also be easily adapted to other applications, including future EVA suits where they could measure metabolic rate for a suited crew member. The first section of the paper discusses the specific technologies and innovations of PUMA.

This paper presents a fire suppression analysis for the Altair project. The architecture of the Altair systems relevant to fire safety is briefly reviewed. This is followed by an outline of a fire safety analysis of the spacecraft including an outline of a probabilistic risk analysis (PRA). The particular emphasis of this analysis is the change in risk as the vehicle moves to lower pressure, higher operating voltage and increased oxygen mole fraction. The analysis shows that all of these changes increase the likelihood and intensity of a fire. The paper then outlines the options for a suppression system followed by a trade analysis of the different options. The candidate systems include inert gas agents (nitrogen, carbon dioxide and helium), water-based systems (spray, mist and foam) and chemically active agents. Chemically active agents are included for reference purposes since they are not likely candidates for the Altair vehicles.