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Title: Development of methodology for astrobiological sampling and analysis
Author: Phillips, Stephen James McGregor
Awarding Body: University of Aberdeen
Current Institution: University of Aberdeen
Date of Award: 2011
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The aim of the thesis is to improve the strategy for exploration of life on Mars and potentially other planetary bodies. This was achieved through the analysis of terrestrial analogues, particularly for targets on the surface of Mars. The search for evidence of life requires optimising several aspects including choice of samples, sample preparation and sample analysis. Analogues selected include snow/ice, evaporites and weathered volcanics. The determination of optimal parameters for extraction of biomarkers was performed on carbon-rich and carbon-poor samples using powdered limestone-shale pairs and on weathered basalt. For all samples, extraction efficiency increased (i) up to about 35°C then did not increase further with temperature; (ii) with smaller grain size; (iii) up to 24 hours extraction time then did not increase further. These data indicate that extraction protocols could be optimised in advance. Dry core drilling experiments showed that the resultant powder obscured visual observation, the range of particle sizes did not allow for the most efficient extraction of organics, and the core powder contained less biomarkers than the core as a result of heating. Extracts of melted Cairngorm snow/ice contained a range of n-alkanols up C18 and extracts of particulate matter contained n-alkanols up to C29. High molecular weight biomarkers are poorly soluble in water, emphasising the importance of optimising the extraction protocol. Samples of snow containing snow algae were successfully analysed for biological pigments using Surface Enhanced Raman Spectroscopy. The development of a bioluminescence assay for the detection of ATP was undertaken in the Cairngorm mountains during a summer and winter season. The detection of ATP was optimised by filtration. An assessment of the potential for site selection, on basalt, from visual parameters, proved that fracture density had the clearest correlation to ATP levels determined by bio-assay. Areas of high fracture density can be detected from Mars orbit, therefore such data could be used to highlight areas most likely to harbour microbes on Mars. The research has shown that terrestrial analogues can yield valuable information on how to optimise different stages of the analysis of a range of rock types that may be expected on Mars.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Exobiology ; Work sampling