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Discrete element modeling of boulder and cliff morphologies on comet 67P/Churyumov-Gerasimenko

Kappel, David and Sachse, Manuel and Haack, David and Otto, Katharina A. (2020) Discrete element modeling of boulder and cliff morphologies on comet 67P/Churyumov-Gerasimenko. Astronomy and Astrophysics, 641 (A19), pp. 1-22. EDP Sciences. doi: 10.1051/0004-6361/201937152. ISSN 0004-6361.

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Official URL: https://www.aanda.org/articles/aa/abs/2020/09/aa37152-19/aa37152-19.html

Abstract

Context. Even after the Rosetta mission, some of the mechanical parameters of comet 67P/Churyumov-Gerasimenko's surface material are not yet well constrained. These parameters are needed to improve our understanding of cometary activity or for planning sample return missions. Aims. We study some of the physical processes involved in the formation of selected surface features and investigate the mechanicaland geometrical parameters involved. Methods. Applying the discrete element method (DEM) in a low-gravity environment, we numerically simulated the surface layer particle dynamics involved in the formation of selected morphological features. The material considered is a mixture of polydisperse ice and dust spheres with inter-particle forces given by the Hertz contact model, translational friction, rolling friction, cohesion from unsintered contacts, and optionally due to bonds from ice sintering. We determined a working set of parameters that enables the simulations to be reasonably realistic and investigated morphological changes due to modifications thereof. Results. The selected morphological features are reasonably well reproduced using model materials with a tensile strength on the order of 1-10 Pa. Increasing the diameters of the spherical particles decreases the material strength, and increasing the friction leads to a more brittle but somewhat stronger material. High friction is required to make the material sufficiently brittle to match observations, which points to the presence of very rough, even angular particles. Reasonable seismic activity does not suffice to trigger the collapses of cliffs without material heterogeneities or structural defects. Conclusions. DEM modeling can be a powerful tool to investigate mechanical parameters of cometary surface material. However, many uncertainties arise from our limited understanding of particle shapes, spatial configurations, and size distributions, all on multiple length scales. Further numerical work, in situ measurements, and sample return missions are needed to better understand the mechanics of cometary material and cometary activity.

Item URL in elib:https://elib.dlr.de/135919/
Document Type:Article
Title:Discrete element modeling of boulder and cliff morphologies on comet 67P/Churyumov-Gerasimenko
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Kappel, Daviddakappel (at) uni-potsdam.dehttps://orcid.org/0000-0002-0518-5548
Sachse, ManuelManuel.Sachse (at) dlr.deUNSPECIFIED
Haack, DavidDavid.Haack (at) dlr.deUNSPECIFIED
Otto, Katharina A.Katharina.Otto (at) dlr.dehttps://orcid.org/0000-0002-0675-1177
Date:2 September 2020
Journal or Publication Title:Astronomy and Astrophysics
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:641
DOI :10.1051/0004-6361/201937152
Page Range:pp. 1-22
Publisher:EDP Sciences
ISSN:0004-6361
Status:Published
Keywords:comets: general – comets: individual: 67P/Churyumov-Gerasimenko – methods: numerical
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):Vorhaben asteroids and comets (old)
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Geology
Deposited By: Otto, Dr. Katharina A.
Deposited On:04 Sep 2020 07:59
Last Modified:04 Sep 2020 07:59

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