Mapping of Fractures at the ExoMars Rosalind Franklin Landing Site

Fractures are ubiquitous in rocks, representing the mechanical stresses exerted on geological materials. They are also of considerable biological interest because of their pivotal role in facilitating fluid circulation within the subsurface. The search for signs of life beyond Earth drives the European Space Agency (ESA) ExoMars Rosalind Franklin (RF) rover mission, which selected the phyllosilicate-rich region of Oxia Planum (latitude 16 °-19 ° N, longitude 23 ° 28 ° W), Mars, as its landing site. In this context, the identification and characterization of fractures are critical in guiding the search for potential biosignatures. Fracture patterns, with spacings ranging from meters to tens of meters, are observable in the region through the Mars Reconnaissance Orbiter (MRO) HiRISE camera, which provides high-resolution optical remote sensing imagery at a resolution of 30 cm per pixel. While the ExoMars team conducted a geological survey focused on the "one-sigma" landing ellipse (approximately 66.75 × 5 km, corresponding to a 67% probability of landing), we initiated a systematic mapping of fractures using HiRISE data through a grid-based mapping approach (1 km by 1 km). Our 1:50,000 scale map represents the current understanding of the spatial distribution of fractures across the "three-sigma" landing ellipse (approximately 115 × 15 km, with a 99% probability of touchdown). Fractures are classified into three categories based on their visibility at 1:5,000 map scale: clearly observable, barely observable, and not observable. By using open geospatial formats, we ensure that datasets produced at different times and in different contexts remain comparable. In this study, we compare our map of fractures with the existing geological map of the Rosalind Franklin landing site, highlighting similarities and differences. By implementing a grid-based mapping approach, we aim to extrapolate additional information and extend the current understanding of the region, providing critical information to support the surface operations of the RF rover. This extended dataset will contribute to the planning of rover exploration activities, provide a framework for testing geological hypotheses about the formation and evolution of Oxia Planum, and facilitate the identification of astrobiologically significant terrains with the potential to preserve biosignatures.

Acknowledgments: This work is supported by the ASI-INAF Mars Exploration agreement code 2023-3-HH 0.