The detection of reactive iron species and associated organic molecules on Mars and in meteorites - implications for sample return

Abstract

This PhD project is centred around the preservation potential of organic matter with reactive iron species with application to Mars, meteorites and sample return missions. Mössbauer Spectroscopy will be used to identify these reactive iron species within samples which will be further analysed by different techniques: Raman Spectroscopy, X-ray Fluorescence, X-ray Diffraction, Chemical sequential extractions, and carbon quantification techniques. Mössbauer spectroscopy, X-Ray Diffraction and Raman spectroscopy have already been used by rovers on the surface of Mars’. However, as each rover landed at different places on the surface of Mars, with different analytical instruments, comparative analysis is difficult. This project hopes to start this comparison whilst also investigating general iron mineralogy and redox environments of different samples (Chapter 3). The identification of iron oxides on Mars is important for preservation of evidence of past life. Both the current Mars 2020 rover, Perseverance, and the postponed ExoMars rover, Rosalind Franklin are equipped with Raman spectrometers for mineral identification. Identification of iron oxides with Raman spectroscopy can cause dehydration to haematite or fluorescence to overwhelm the resulting spectrum. Within this work, parameters to safely analyse iron oxides with Raman spectroscopy are begun to be investigated and what this means for finding evidence of past life on Mars (Chapter 4). The techniques listed above will be used on Mars analogues from various sites on Earth to compare mineral detections by the different instruments. Following this, the analogues will undergo sequential extractions to determine the amount of organic carbon bound to reactive iron species within the samples (Chapter 5). Another aim of this project is to analyse alteration of carbonaceous chondrite meteorites with Mössbauer Spectroscopy and how this relates to the preservation of organic matter (Chapter 6). Finally, results will be discussed and analysed in the greater context of the importance of mineralogical technique selection and the importance of sample return missions. Overall, this work aims to highlight the importance of correct mineralogical analytical technique for extraterrestrial missions and why sample return missions are of high importance for understanding geology of bodies other than Earth.