Browsing by Author "Carlsen, Christopher"
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Item Investigation of a Solid-State Cooling System for Analog EVA Life Support(48th International Conference on Environmental Systems, 2018-07-08) Carlsen, Christopher; Akin, DavidSpacesuit simulators are used for analog testing on Earth to simulate the look, feel, and bulk of a spacesuit to the wearer while performing test operations. These simulators are low cost and reasonably high fidelity, reducing the cost and complexity of analog testing while providing some of the physiological strain of extravehicular activity (EVA). Cooling analog spacesuits is required due to their bulk, and is accomplished with a liquid cooling garment (LCG). Simulator LCGs had been cooled by melting several kilograms of water ice packaged into the simulated portable life support system (PLSS) carried on the user's back. This was effective in cooling the test subject, but difficult operationally as cooling requirements can approach ten kilograms of ice per hour, requiring a ready supply of ice to be on location or limiting the duration of analog EVAs. To address the shortcomings of ice cooling, a system using thermal-electric coolers (TECs) was devised. The end goal of this design was to make an equivalent system that requires a lower mass in batteries than the previous solution would in ice. A systems level analysis found the efficiency of the TECs are highly dependent on the thermal resistance between TEC, heat source, and heat sink, as well as on the current used by the junction. It proved necessary to use multiple liquid cooling loops to achieve an efficiency high enough to demonstrate a significantly higher mass efficiency than using ice. Using a TEC-based system is also simpler operationally, as the user can change batteries or attach to a power supply rather than add ice to the system. This system was found to be sufficient for cooling a user while standing still and walking at a normal pace. Further expansion of this design will allow for higher metabolic workloads, lower mass, and higher efficiency.Item Random Access Frame (RAF) System Neutral Buoyancy Evaluations(45th International Conference on Environmental Systems, 2015-07-12) Howe, A. Scott; Polit-Casillas, Raul; Akin, David L.; McBryan, Katherine; Carlsen, ChristopherThe Random Access Frame (RAF) concept is a system for organizing internal layouts of space habitats, vehicles, and outposts. The RAF system is designed as a more efficient improvement over the current International Standard Payload Rack (ISPR) used on the International Space Station (ISS), which was originally designed to allow for swapping and resupply by the Space Shuttle. The RAF system is intended to be applied in variable gravity or microgravity environments. This paper discusses evaluations and results of testing the RAF system in a neutral buoyancy facility simulating low levels of gravity that might be encountered in a deep space environment.