Fig. 1: Overview of targets analysed by SHERLOC during the crater floor campaign.

a, High Resolution Imaging ScienceExperiment (HiRISE) image of the region studied with the rover’s traverse marked in white, the boundary between the Séítah and Máaz fm delineated by the light blue line, and each rock target labelled. Scale bar, 100 m. b, Average number of fluorescence detections (out of 1,296 points) from survey scans for each target interrogated by SHERLOC, arranged in order of observation. *The acquisition conditions were different for dust-covered natural targets as compared to relatively dust-free abraded targets, possibly resulting in reduced detections. c, WATSON images of natural (red box) and abraded targets (Máaz is the blue box, Séítah is the green box) analysed in this study, with SHERLOC survey scan footprints outlined in white. Two survey scans were performed on Guillaumes, Dourbes and Quartier. Sol 141 imaging on Foux had an incomplete overlap of WATSON imaging and SHERLOC spectroscopy mapping. Scale bars, 5 mm.