Detecting life on Mars through the study of organic host Mars analogues and Urey instrument development

Abstract

The search for life on Mars is one of today’s most exciting and far-reaching scientific challenges. The European Space Agency’s ExoMars mission will renew the pursuit of signs of past or present life equipped with a range of analytical instruments: one such instrument will likely be Urey, a tool that will extract and analyze organic molecules. This thesis first seeks to contextualize the search for life through the use of analogue sites on Earth and ultimately works to optimize the spectrofluorometric detection of relevant organic molecules. Organic host analogues – sites on Earth where life faces similar challenges as potential martian life forms – aid in mission planning and data analysis. With these dual purposes in mind and the understanding that collaborative analogue use benefits all stakeholders, the Imperial College Mars Analogue Repository (ICMAR) was established. Samples from Iceland and the Middle Atlas mountains of Morocco were gathered to start the collection. As it grows, mission planners and scientists will have a centralized, well-characterized set of samples for astrobiological studies. Optimizing Urey’s spectrofluorometric detection of amino acids and polycyclic aromatic hydrocarbons (PAHs) was another primary aim of this study. Standard solutions were tested across a range of instrumental parameters and an ideal excitation wavelength was identified to optimize the detection of any organics present at the sampling site. The fluorescent interaction between molecules was also investigated to evaluate the instrument’s ability to detect and quantify complicated, multicomponent samples. Finally, natural organic-rich samples from England’s Blue Lias formation were tested to evaluate spectrofluorometric analysis of natural samples – a capability that will be crucial for in situ martian analysis. By highlighting the role of organic Mars analogues and optimizing the Urey instrument, this thesis enhances ExoMars’ ability to identify organic molecules and sets the stage for continued martian exploration.