34-5 Quantifying interactions between dust devils and recurring slope lineae from reflectance change: Implications for Martian slope lineae formation processes

Session: Geobiology and Astrobiology in Modern and Ancient Environments: From Microbial Interactions to Planetary Exploration

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Abstract:

While the influence of large-scale dust-driven events on Mars has been studied in detail, the interactions between transient, smaller-scale dust-driven events such as dust devils (DD’s) and hillslope processes of currently-unknown origin such as recurring slope lineae (RSL) are still relatively unexplored. As such, the apparent rare occurrence of DD’s and their associated light- and dark-toned dust devil tracks (LDDT’s and DDDT’s) overprinting RSL allows for further extraction of information, revealing additional unstudied processes that can help better elucidate RSL formative mechanisms.

To further elucidate these RSL-DD interactions, we conducted a three-part study to quantify the change in reflectivity from interactions between dust devils and RSL using the bidirectional reflectance distribution function to correct for differing viewing angle- and roughness-related parameters. We established a baseline that showed that RSL, crater walls, and dust devil tracks showcased increasing reflectivity respectively, with no major reflectivity change observed per surface cover type between five High-Resolution Imaging Science Experiment (HiRISE) images that spanned two Martian years (MY).

We then characterized relative change in reflectivity by moving laterally across an LDDT and downslope along multiple RSL features, finding that the RSL and LDDT’s exhibited no statistically significant reflectivity change along each transect or track, save for statistically significant increases in reflectivity where LDDT’s interacted with RSL. Finally, we quantified changes in reflectivity within and near LDDT-RSL interactions dependent on terrain cover combinations and found that dust devil tracks traversing bare ground typically exhibited the highest reflectivity, that RSL lowered the reflectivity of the surfaces they covered by up to 10%, and that the LDDT-RSL intersection areas had an albedo intermediate to these two endmembers.

This research has implications for both the small-scale interaction between surface grains and their cohesiveness and the larger-scale formation of and interaction between features on Mars, including both light- and dark-toned dust devil tracks and the presence of low-albedo recurring slope lineae. Given the changes in reflectivity observed between differing terrain types and within different types of terrain covers, a dry formation mechanism for RSL appears most likely.

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