Detecting habitability signatures using spectroscopy on the ESA ExoMars Mars rover

**This project has guaranteed funding from the UK Space Agency for starting October 2024**

Overview 

Two robotic rovers are exploring the Martian surface with a focus on past habitability and detection of biosignatures – NASA Curiosity and Perseverance, with the ESA ExoMars rover Rosalind Franklin set for launch in 2028. All three rovers utilise a combination of visible – near infrared (Vis-NIR) multispectral and shortwave infrared (SWIR) spectroscopic measurements. For Rosalind Franklin, rock and soil geochemistry will be inferred from multi- and hyper-spectral reflectance measurements. These measurements will be provided by Enfys, an IR spectrometer (900 – 3200 nm) and the multispectral Panoramic Camera (PanCam), in addition to other spectroscopic instruments on Rosalind Franklin. This PhD project will provide underpinning science for PanCam and Enfys in preparation for the ExoMars rover mission, exploring the scientific utility of these two instruments in combination using a suite of Mars-analogue geological samples. 

Project Description 

You will investigate how the multidimensional spectral parameters provided by PanCam and Enfys indicate changes in chemistry and mineralogy that are conducive to the capture and preservation of organic carbon. Multidimensional spectral parameters include features such as band depths, ratios, slopes, band minima and maxima, and combinations of these, which describe the unique reflectance properties of a material. As a new addition to the Rosalind Franklin instrument payload, Enfys requires dedicated scientific testing with respect to its scientific utility both in isolation and as a complementary instrument to PanCam. Your project will focus on two core studies, however there is research flexibility inherent to both. 

Study 1 | Cross-instrument spectral parameters for Mars analogue organic-bearing materials. You will test the hypothesis that mineralogical and compositional features associated with low sedimentation rates, chemically-reducing conditions, and, as a consequence of these, locally-elevated organic carbon, can be confidently identified with spectral data generated using PanCam and Enfys measurements of Mars analogue samples. Earth’s rock record serves as a valuable guide for understanding where, and the extent to which, microbial biomass can be preserved for billions of years. Complementing this archive, younger sedimentary strata provide analogues that have not undergone high-grade metamorphism, a process largely absent on Mars. You will investigate the geochemically-influenced spectral signatures imparted through major and trace element compositions of the host deposits and co-preserved inorganic trace phases that are spatially associated with organic-rich horizons or deposits within natural, heterogeneous samples.  

Study 2 | Investigating clay mineral provenance. Clay minerals are high-priority targets on Mars due to their ability to sequester organic matter. You will test the hypothesis that qualitative spectral measurements can be related to quantitative element geochemistry for sediments recording different alteration histories. For this, you will use existing samples of mafic fluvial and lacustrine sediments from Iceland.  

Methods

Fieldwork to Scotland will be conducted in Spring 2025 to collect additional samples and take in situ spectroscopic measurements with instrument emulators.

Geochemistry

Samples will be characterised with respect to (i) mineralogy and kerogen by micro-Raman spectroscopic mapping; (ii) whole rock mineralogy by X-Ray Diffraction (XRD) including clay speciation; (iii) whole rock Total Organic Carbon (TOC) by Elemental Analyser; (iv); spatially-mapped major and minor elemental composition by Energy Dispersive X-Ray and Electron Microprobe mapping; and (v) trace element geochemistry by solution or laser-ablation ICP-MS.

Spectroscopy

Samples will be analysed at the Space Instrumentation Laboratory at Aberystwyth University by (i) VNIR (400 – 1000 nm) hyperspectral imaging, resampled to PanCam spectral resolutions, (ii) Vis - SWIR (400 – 2500 nm) reflectance spectroscopy under controlled lighting and viewing geometries, and (iii) with the Enfys breadboard instrument (900 – 3200 nm).

Data analysis

Hyperspectral image data will be analysed using ENVI and the PanCam Operations Toolkit (PCOT) software in development at Aberystwyth University that will be used for the ExoMars rover mission. Results from this study will feed back into the ongoing development of PCOT. 

Supervision and Training

Collectively the supervisory team has expertise in planetary exploration (Cousins; Grindrod), optical instrumentation (Gunn), and Archaean geology and biosignatures (Stüeken). The team includes the Enfys PI (Gunn), and science feasibility leads (Grindrod, Cousins) and PanCam Co-Is (Cousins, Gunn, Grindrod). All PhD students are additionally assigned an independent mentor upon starting, and all supervision is carried out under the University of St Andrews PGR Code of Conduct. You will follow the GRADskills training programme run by the St Andrews Organisational, Staff, and Development Services (OSDS). You will receive hands-on training by technicians for the microanalytical techniques used, plus spectroscopy and data analysis. You will become a member of the ExoMars PanCam and Enfys Science Teams. There is also the option to attend Honours and Masters-level taught classes in SEES on topics such as Processes and Products in Sedimentary Systems, Data Analysis in Earth Science, Analytical Methods in Geochemistry, and The Chemistry of the Solar System. 

Research environment

You will become part of the “Planets and Life” research theme in SEES, the cross-disciplinary Centre for Exoplanet Science at St Andrews, and also be affiliated with the NHM. You will have the opportunity to participate in our internal Seminar Series, contribute to conference hosting, and discuss research in settings ranging from social coffee, annual PhD conference, and ECR away days. Further, you will be a member of the St Leonard’s Postgraduate College. 

Skills and Background

This project will suit someone with either a geoscience or planetary science background, with a keen interest in Mars exploration and/or instrumentation. Experience with GIS software and/or geochemical analysis would be advantageous but not essential. For informal enquiries and further information, please contact Claire Cousins (crc9@st-andrews.ac.uk).

Application Process

Please apply via the St Andrews application webpage

Following the guidance specific to the School of Earth and Environmental Sciences. The deadline for applications is 7 January 2024, 17.00 GMT. All applications will be reviewed by the project supervisory team and an internal academic panel at the University of St Andrews. Shortlisted applications will be invited for interview, which usually lasts 30-60 minutes.