Novel modern terrestrial analogues for potential life-favouring environments on ancient Mars

With the landing of the Mars2020 rover Perseverance, a new generation of Martian research is possible. This mission will return samples from Jezero crater, including those from settings that were likely wet (e.g., as evidenced by smectite clays and carbonate sequences) and therefore possibly habitable in the Martian past. Tremendous strides in proxy development have opened up windows to reconstructing past microbial ecology, pH and alkalinity on Earth. We propose to extend these advances to Martian samples, but such efforts will require a new generation of paleo-proxy validation and calibration in terrestrial analogues. These analogue locations include famous alkaline settings that remain unexplored using the planned methods: Lake Myvatn in Iceland, the Coorong coastal lagoon in Australia, and Lake Salda in Turkey. The student will use i) organic biomarkers to reveal ecologies associated with highly alkaline setting and ii) boron and nitrogen isotope analysis to provide perspectives of pH and alkalinity conditions. Additional biomarkers (e.g. glycerol ether lipids) will provide further constraints on pH. These parameters will help define the conditions of potential past life on Mars and expanded possibilities for biosignatures, particularly once Martian samples are returned and analysed in our labs in the coming years. The overarching goal is to develop an interdisciplinary strategy for exploring possible microbial ecology on ancient Mars, emphasizing alkaline settings that are hypothesised from Mars' wet past and shown on Earth are known to harbour large and diverse microbial communities. This study also speaks broadly to habitability on high-pH bodies such as Enceladus and exoplanetary water worlds as targets in the search for extraterrestrial life.