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Grainflow Modeling of Martian Recurring Slope Lineae

Presentation #515.03 in the session Mars Surface (iPosters).

Published onOct 20, 2022
Grainflow Modeling of Martian Recurring Slope Lineae

Recurring Slope Lineae (RSL), seasonally varying dark streaks on Mars’ surface of unknown origin remain some of the most poorly understood features on Mars. These features have been considered the best evidence for liquid water flow on the surface of Mars, but a competing hypothesis for the origin of these enigmatic features does not require water and instead forms them via wind-cached grainflows. This hypothesis suggests that seasonal changes in winds act to cache lofted sand in locations where: (1) upslope saltation (grain transport) is impeded by large topographic rises (outcropping bedrock), or (2) downslope saltation is minimized due to wind shadowing outcropping bedrock. This cache then accumulates until slope failure. The released sand due to slope failure would then produce a dark streak as it displaces dust on the surface thereby producing an RSL without requiring liquid water. Confirming or refuting whether dry grainflows can produce these features has important implications for our understanding of water on Mars. Small aeolian features are below the resolution of available observations, so supporting evidence for this hypothesis requires simulating the conditions that would yield these features and comparing these simulated grainflows to RSL observations. Grainflow simulations can be produced via discrete element method modeling using the open-source software LIGGGHTS. This software is capable of simulating millions of particles with tunable properties (including particle size distribution and material) while under the influence of tunable external forces. We present results from our investigation of the hypothesized dry grainflow mechanism for RSL formation through parametric studies carried out using LIGGGHTS to identify grainflow conditions that would produce observed RSL flow rates and extents measured from HiRISE observations of Rauna crater.

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