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Investigating the Effects of Dust Re-Settling on Near-Surface Activity on Comet 67P/C-G

Presentation #408.03 in the session Comets: Nucleus (Oral Presentation)

Published onOct 23, 2023
Investigating the Effects of Dust Re-Settling on Near-Surface Activity on Comet 67P/C-G

The transport and redistribution of dust around cometary nuclei is of great interest for understanding the uppermost layer of the surface, its thermal and physical properties, and its origins. Additionally, dust particles settling onto the nucleus may, over time, form a protective layer that hampers further sublimation of near-surface ices. On comet 67P/C-G, whose northern hemisphere is coated with dust originating from the active southern hemisphere each apparition [1], this feedback process would result in a global asymmetry in dust and gas emission: as dust is deposited onto the northern hemisphere, activity would slow and potentially cease as the dust mantle thickness becomes larger than the diurnal skin depth; conversely, dust entrainment by the sublimating gas in the active southern hemisphere would act to reduce the mantle thickness, thereby enabling further sublimation of near-surface ices. Utilizing a dust transport model in conjunction with a thermal model [2], this study investigates the dynamic relationship between dust deposition, erosion, and the sublimation rate of volatiles, principally H2O, on comet 67P throughout its orbit. We employ a high-resolution digital shape model to explore the spatial variability in this feedback process at local scales, where previous work [2] has shown strong heterogeneities in dust fallback due to topographic shielding at scales of tens of meters.

[1] Keller, H. U. (2017). MNRAS, 469(Suppl_2), S357-S371. [2] Kloos, J. L. (2023). Asteroids, Comets and Meteors Conference, LPI Contrib. No. 2851.

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