Organic matter in the most extreme environments: arid zone soils, rock varnishes and multi-technique analyses of Mars analogues

The Viking Landers in the 1970s demonstrated that the search for life on the surface of Mars is a formidable scientific challenge (Navarro-Gonzalez et al., 2006). As new missions have been developed to address this question the importance of understanding the character of organic matter in Mars-like environments on Earth has become readily apparent.

Terrestrial desert environments have been proposed as “Mars Analogues” (Fairén et al., 2010, Hutchinson et al., 2014). These provide vital opportunities to develop and test new instrumentation to detect life (or its remains) on planetary surfaces (Navarro-Gonzalez et al., 2003; Edwards et al., 2012). Hyper-arid environments also allow us to test the limits of life on Earth by developing an understanding of the habits of extremophile organisms and the functioning of the soil C and N cycles under conditions of extreme aridity.

Relatively recently it has been shown that organic matter in some characterisable form can be detected in soils from even the most arid regions (Navarro-Gonzalez et al., 2006). The purpose of this PhD is to understand the molecular composition and preservation mechanisms of organic matter in arid and hyper-arid environments. Forthcoming Mars missions (ESA ExoMars and NASA2020) will be equipped with miniature Raman spectrometers (RS) which are designed to detect organic biomarkers, particularly UV-protective pigments. A key goal of this PhD is therefore to test flight-equivalent RS instruments in desert settings in order to refine instrument design and to provide vital assistance for future interpretations of RS data obtained from the Martian surface.

The work also has wider implications. Only recently have researchers begun to consider the origins and character of organic matter in the most extreme desert ecosystems and such work hints at fundamental changes in the functioning of the carbon and nitrogen cycles in such environments (Ewing et al., 2006). This study will therefore also provide an opportunity to consider basic mechanisms of organic matter creation / degradation / preservation under hyper-arid conditions (Carr et al., 2013). Given the extent of the world’s drylands, such findings have wider implications for the global C and N cycles.

We are an equal opportunities employer and particularly welcome applications for Ph.D. places from women, minority ethnic and other under-represented groups.