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A Sublimation Model for Exploring Cometary Activity and Surface Morphology of 67P/C-G

Presentation #312.02 in the session Physical Characteristics of Cometary Nuclei (iPosters).

Published onOct 20, 2022
A Sublimation Model for Exploring Cometary Activity and Surface Morphology of 67P/C-G

The Rosetta spacecraft spent ~2 years orbiting comet 67P/Churyumov-Gerasimenko (hereby 67P/C-G), during which it mapped the entire surface of the nucleus at submeter resolution and revealed its complex surface morphology composed of numerous classes of terrain, including rough, pitted terrain as well as smooth, dust-covered surfaces [1]. In addition, more dynamic surface features were also observed, including depressions that expand radially outward at rates as high as 10 m/day, presumably as a result of insolation-driven sublimation of near-surface ices [2]. In this work, we present a thermophysical model that is used to explore the formation and evolution of the aforementioned surface features on comet 67P/C-G. A digital shape model is used to simulate the incoming solar insolation at each facet, and a ray-tracing algorithm is used to incorporate shadowing and self-heating effects. Surface and sub-surface temperatures are computed using a 1-D thermal model that accounts for the physical and compositional properties of the surface (albedo, porosity, grain size, ice content, etc.), and these temperatures are used in turn to estimate the resulting gas production and surface erosional rates. As well, this model incorporates mass transport and will be applied to explore the spatial redistribution and depositional rates of sublimated material by simulating particle trajectories in the microgravity environment of CG. The presented results from these simulations will seek to constrain the underlying processes, and associated timescales, that govern the complex evolution of the surface topography.

[1] Thomas, N. et al. “The morphological diversity of comet 67P/Churyumov-Gerasimenko.” Science 347.6220 (2015): aaa0440. [2] Groussin, O. et al. (2015) ‘Temporal morphological changes in the Imhotep region of comet 67P/Churyumov-Gerasimenko’, Astronomy and Astrophysics, 583, p. A36. doi: 10.1051/0004-6361/201527020.

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