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Investigation of Fresh Impact Crater Depths on Titan

Presentation #405.05 in the session “Titan Surface-Atmosphere Interaction”.

Published onOct 03, 2021
Investigation of Fresh Impact Crater Depths on Titan

Saturn’s largest moon, Titan, is the only planetary body in our solar system, besides Earth, that has liquid on its surface and a thick, nitrogen-rich atmosphere. NASA’s Cassini mission mapped the surface of Titan and detected an unusually low number of impact craters. This low count is likely the result of erosion and deposition altering the crater morphologies, such that they are unrecognizable from orbit. Cassini data also shows morphological indicators of fluvial erosion and aeolian infill in Titan’s craters. As a result, we don’t know the original, ‘uneroded’ morphology of Titan’s impact craters: information that is necessary to constrain the amount of erosion that has occurred since their emplacement. Numerical modeling would allow for an improved understanding of fresh crater morphologies on Titan. A comparison of Titan crater depths to Ganymede craters has already provided evidence of erosional processes on Titan; the impact craters on Titan are hundreds of metres shallower than expected. However, this result is based on the assumption that the initial crater depths on Titan are comparable to similarly sized craters on Ganymede and Callisto. Given the potentially different compositions of their surfaces (methane clathrate vs. water ice) and thermal structures of their interiors, this may be a poor assumption. As a result, we need models of more realistic “fresh” Titan craters. This study will simulate impact crater formation on Titan using the impact-Simplified Arbitrary Lagrangian Eulerian (iSALE) shock physics code. The simulations will explore how varying Titan’s crustal properties affects the crater depths over a range of diameters. We will investigate a range of thicknesses for its ice crust (40–100 km), as well as a range of thermal gradients in the ice crust (3–10 K/km). The resulting depths of fresh Titan impact craters will then be compared to the observed depths of craters on Titan, to determine the extent by which erosion has shaped its surface.

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