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Title: A compact borehole, thermal-infrared radiometer and infrared reflectometer for the characterization of subsurface habitability and presence of water ice on Mars
Author: Fletcher, Lauren
ISNI:       0000 0004 6499 0840
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2016
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One of the most important steps in the search for life on Mars is to determine if a specific sub-surface location it is "habitable", or that it provides the conditions and requirements to support life as we know it. In this thesis, I present a miniature, thermal-IR radiometer and reflectometer designed to determine temperature, the presence of water ice, and the discrimination of minerals, all necessary for a habitable environment. A dual use detector was selected for the thermal and five reflectance channels. The IR source is provided by five LEDs. These components were embedded in a thermally controlled aluminium block. Integrated electronics provided signal amplification and demodulation. This device will be suitable for drilling applications with less than 25 mm diameter boreholes and with limited available power (<5watts). Thermal testing was within a simulated borehole mounted in a thermal vacuum chamber. The results were compared to a theoretical model of the expected temperature. The maximum temperature error between predicted and measured was 0.21 K (∼0.08%). The total RMS error of all sources were calculated to be <3%. Reflectance testing in all five channels included a variety of minerals and a two point calibration method. The results were compared to the predicted reflectance values for the samples. The results of the reflectance channel testing demonstrated that the measured values matched the predicted values with a 2.5% measured error. The total RMS error was 6.1%. Detection and discrimination of water ice and hydrated minerals included a non-linear mixing model and/or testing. The model predicted that water ice mixed in a pyroxene mineral matrix can be detected and discriminated from 5% to 60% concentration by weight. Testing with a hydrated mineral mixed within a non-hydrated mineral matrix demonstrated that the measured result matched the predicted result from 5-45% concentration by weight.
Supervisor: Bowles, Neil E. Sponsor: NASA
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Thermal IR Radiometer ; Mars Exploration Technologies ; Multi-channel NIR Reflectometer ; Mars Technologies ; NIR reflectometer