What lies beneath the surface of Mars? Advanced Numerical Modelling and Data Intensive Processing for Large and Complex Ground Penetrating Radar Data

Planetary subsurface exploration is a rapidly growing international scientific endeavour and a key part of the UK's Space Science Programme. The primary tool for surface and subsurface planetary exploration is the autonomous instrumented rover, with 3 currently active on Mars - Curiosity (NASA, 2012), Perseverance (NASA, 2021), and Zhurong (CNSA, 2021) - and Rosalind Franklin (ESA) to deploy in 2028.

The operational lifespan and distances surveyed by the rovers mean that large volumes of scientific data are being generated, e.g. Opportunity (NASA, 2003) holds the record for the longest distance driven on another planet (45km).

The most recently deployed (and planned) Mars rovers include Ground Penetrating Radar (GPR) as part of their scientific instrumentation. GPR is well-suited for imaging the subsurface of Mars because it provides high resolution continuous measurements, and can operate in dry, low-conductivity environments with minimum operational input. It is capable of accurately mapping the dielectric properties of the Martian subsurface up to depths of tens of metres, which can then be used to infer mineralogical and mechanical properties and reveal the both the stratigraphy and structure of the area.

Vast quantities (tens of kilometres) of GPR data are being generated by Perseverance, and similar data are expected from the GPR on Rosalind Franklin. Current GPR data processing techniques are inadequate for two key reasons: 1) they are based on a conventional workflow, i.e. time-varying gain, background removal, and simplistic hyperbola fitting, which is not suitable for the unique Martian subsurface environment; and 2) they do not provide automated interpretation at scales to manage the large volume of GPR data being acquired.

The fundamental aim of this project is to develop a new generation of open-source numerical modelling and data intensive processing tools for planetary GPR surveying. This will enable new knowledge of subsurface material properties and structures, such as the detection of liquid water on Mars, the study of habitability in Martian caves, and allow planning for the construction of future planetary infrastructure.

The project will develop and utilise gprMax (http://www.gprmax.com/), which is open-source EM modelling software already used by the RIMFAX project team (NASA) and China National Space Administration (CNSA) for Mars and Lunar GPR investigations. The research will focus on large volume, multi-offset GPR data and amplitude versus offset (AVO) analysis, as well as the development of an EM digital twin of the GPR/lander system which will allow its characteristics and performance to be investigated, and be a significant step forward for model-based processing.