Browsing by Author "Phillips, Straun"
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Item Compact Multi-gas Monitor for Life Support Systems Control in Space: Evaluation Under Realistic Environmental Conditions(44th International Conference on Environmental Systems, 2014-07-13) Alonso, Jesús Delgado; Phillips, Straun; Chullen, Cinda; Mendoza, EdgarAdvanced space life support systems require lightweight, low-power, durable sensors for monitoring critical gas components. A luminescence-based optical flow-through cell to monitor carbon dioxide, oxygen, and humidity has been developed and was demonstrated using bench-top instrumentation under environmental conditions relevant to portable life support systems, including initially pure oxygen atmosphere, temperature range from 50°F to 150°F, and humidity from dry to 100% RH and under conditions of water condensation. This paper presents the most recent progress in the development of this sensor technology. Trace gas contaminants in a space suit, originating from hardware and material off-gassing and crew member metabolism, are from many chemical families. The result is a gas mix much more complex than the pure oxygen fed into the space suit, and this complexity may interfere with gas sensor readings. This paper presents an evaluation of optical sensor performance when exposed to the most significant trace gases reported to be found in space suits. A study of the calibration stability of the sensors is also presented. For that purpose, a profile of temperature, pressure, humidity, and gas composition for the duration of an EVA has been defined, and the performance of sensors operated repeatedly under those conditions has been studied. Finally, this paper presents the first compact readout unit for these optical sensors, designed for the volume, power, and weight restrictions of a PLSS.Item Non-intrusive, Distributed Gas Sensing Technology for Advanced Spacesuits(45th International Conference on Environmental Systems, 2015-07-12) Delgado, Jesús; Phillips, Straun; Rubtsov, Vladimir; Chullen, CindaChemical sensors for monitoring gas composition, including oxygen, humidity, carbon dioxide, and trace contaminants, are needed to characterize and validate spacesuit design and operating parameters. This paper reports on the first prototypes of a non-intrusive gas sensing technology based on flexible sensitive patches positioned inside spacesuit prototypes and interrogated via optical fibers routed outside the suit, taking advantage of the transparent materials of the suit prototypes. The sensitive patches are based on luminescent materials whose emission parameters vary with the partial pressure of a specific gas or temperature. Patches sensitive to carbon dioxide, humidity, and temperature have been developed, and their preliminary laboratory characterization in Mark III-like helmet parts is described. The first prototype system consists of a four-channel fiber optic luminescent detector that can be used to monitor any of the selected target gases at four locations. To switch from one gas to another, we replace the (disposable) sensor patches and adjust the system settings. Repeatability among sensitive patches and of sensor performance from location to location has been validated. This assures that suit engineers will have flexibility in selecting multiple sensing points, fitting the sensor elements into the spacesuit, and easily repositioning the sensor elements as desired. The evaluation of the first prototype for monitoring carbon dioxide during washout studies in a spacesuit prototype is presented.