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Technical Paper

Results and Analysis from Reduced Gravity Experiments of the Flexible Membrane Commode Apparatus

2009-07-12
2009-01-2344
Two separate experimental rigs used in tests on NASA and Zero-G Corporation aircrafts flying low-gravity trajectories, and in the NASA 2.2 Second Drop Tower have been developed to test the functioning of the Flexible Membrane Commode (FMC) concept under reduced gravity conditions. The first rig incorporates the flexible, optically opaque membrane bag and the second rig incorporates a transparent chamber with a funnel assembly for evacuation that approximates the size of the membrane bag. Different waste dispensers have been used including a caulking gun and flexible hose assembly, and an injection syringe. Waste separation mechanisms include a pair of wire cutters, an iris mechanism, as well as discrete slug injection. The experimental work is described in a companion paper. This paper focuses on the obtained results and analysis of the data.
Technical Paper

Smoke Particle Sizes in Low-Gravity and Implications for Spacecraft Smoke Detector Design

2009-07-12
2009-01-2468
This paper presents results from a smoke detection experiment entitled Smoke Aerosol Measurement Experiment (SAME) which was conducted in the Microgravity Science Glovebox on the International Space Station (ISS) during Expedition 15. Five different materials representative of those found in spacecraft were pyrolyzed at temperatures below the ignition point with conditions controlled to provide repeatable sample surface temperatures and air flow conditions. The sample materials were Teflon®, Kapton®, cellulose, silicone rubber and dibutylphthalate. The transport time from the smoke source to the detector was simulated by holding the smoke in an aging chamber for times ranging from 10 to1800 seconds. Smoke particle samples were collected on Transmission Electron Microscope (TEM) grids for post-flight analysis.
Technical Paper

Development of Waste Bag Air Flow and Drying Models for Solid Waste Management

2007-07-09
2007-01-3263
NASA is developing a novel waste bag concept for filling, storing and drying astronaut fecal material. The three-layer bag is lined with a membrane that is impermeable to solid and liquid matter but permeable to gases. The air flow provided by a blower assists in containing the waste in the bag. After use, the bag is sealed and then connected to a vacuum manifold for drying the waste. This paper describes the development of theoretical models for analyzing the air flow patterns in the bag during the filling process as well as the parameters governing the drying rate. The models will be used to support the design and testing of the waste bag.
Technical Paper

Fire Suppression Technology in Human-Crewed Spacecraft -A Trade Study

2007-07-09
2007-01-3256
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).
Technical Paper

A Portable Unit to Measure Metabolic Rate during Shirtsleeve and Suited EVA Tests

2008-06-29
2008-01-2110
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.
Journal Article

Measurement of Smoke Particle Size under Low-Gravity Conditions

2008-06-29
2008-01-2089
Smoke detection experiments were conducted in the Microgravity Science Glovebox (MSG) on the International Space Station (ISS) during Expedition 15 in an experiment entitled Smoke Aerosol Measurement Experiment (SAME). The preliminary results from these experiments are presented. In order to simulate detection of a prefire overheated-material event, samples of five different materials were heated to temperatures below the ignition point. The smoke generation conditions were controlled to provide repeatable sample surface temperatures and air flow conditions. The smoke properties were measured using particulate aerosol diagnostics that measure different moments of the size distribution. These statistics were combined to determine the count mean diameter which can be used to describe the overall smoke distribution.
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