Fracture mapping from orbital imagery: a case study of Oxia Planum, Mars

Le résumé fourni par la source

Rock fractures on planetary bodies provide critical insights into composition and geologic history. On Earth, fracture mapping is performed manually on-site or remotely through drone, aircraft, or orbital photography. On other planets, fracture mapping mainly relies on orbital data, with on-the-ground confirmation only possible in very limited areas. To date, a repeatable and clearly defined workflow for fracture mapping from orbital data has not been presented. Here, we present a workflow protocol for producing comparable and consistent fracture data using orbital imaging. We present a case study of Oxia Planum, Mars, the landing site for the European Space Agency's ExoMars Rosalind Franklin Rover mission. On Mars, the High Resolution Imaging Science Experiment (HiRISE) provides over 100,000 0.25-0.50 m/px orbital images, equivalent to very-high resolution orbital imagery of Earth. Existing fracture mapping products around Mars are not directly comparable due to the interpretive nature of fracture mapping and a bias which leads to characterizing the most clearly visible fractures. This study leverages field fracture mapping expertise to present an unbiased, reproducible approach, and provides recommendations for basic statistical assessment of fracture data. We found that fracture density is reproduced to ±5%, and minimum visual resolvability of fracture lengths is 0.5 cm on screen. Comparison of fracture data with bedrock characteristics confirms the general unit descriptions for the area, where visually bright, clay-rich rocks are more fractured than other units, with significantly higher numbers of fractures and sum fracture lengths (387% and 360%, respectively).

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