Development of an optimised detection system for a stand-off Raman spectrometer for planetary and lunar exploration

2018-07-30T12:20:09Z (GMT) by Melissa McHugh
Raman spectroscopy is a chemical and molecular structural identification technique which is sensitive to the vibrational modes of molecules. It is used in many fields, including: pharmaceuticals, security/defence and nuclear waste. In the past decade, significant advances in the miniaturisation and robustness of key technologies have also led to the consideration of Raman spectroscopy for application in the field of planetary exploration and in 2020 the first Raman instruments will be launched as part of two missions to the surface of Mars. The first is ESA’s ExoMars rover, which will include a compact macroscopic Raman instrument within its analytical laboratory. The second is NASA’s Mars2020 mission which will feature a stand-off Raman spectrometer: an instrument that provides a method of retrieving molecular information from remote distances, enabling rovers to investigate otherwise inaccessible regions. However, current stand-off and in situ instrument designs are limited by the challenging resource constraints associated with deploying systems on rover platforms, resulting in the need for detailed system software models and instrument prototypes that enable complex trade-offs and optimisations to be performed. This thesis presents work completed in preparation for the ExoMars, Mars2020 and other future planetary exploration missions that require information on molecular composition to fully address their science goals. It describes the development of sophisticated, end-to-end radiometric models and detailed software simulation tools for predicting and evaluating the performance of miniaturized Raman instrumentation. Details on the development of a prototype stand-off Raman instrument, designed to verify the software models are also provided, along with results from a number of instrument performance and model verification tests, including detector radiation damage campaigns. Several studies completed in order to assess and demonstrate the performance of various prototype and flight representative Raman instruments are also reported, including laboratory investigations of mission relevant sample standards and two field test campaigns.

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