BORIS Theses

BORIS Theses
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Planetary-Scale Impacts and their Geophysical Consequences

Ballantyne, Harry (2022). Planetary-Scale Impacts and their Geophysical Consequences. (Thesis). Universität Bern, Bern

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Planetary-scale impacts are thought to have been common during the final stages of planet formation. Such events may be responsible for many of the most distinguishing features of the Solar System’s celestial inhabitants, such as the stark contrast between the two hemisphere’s of Mars, known as the Martian Dichotomy, or the relatively small iron core and high angular momentum of the Moon. With such long-term consequences, the study of planetary-scale impacts requires the careful consideration of both the highly energetic, shock-inducing conditions directly after the impact and the geophysical implications that follow. In this thesis, such an approach is adopted throughout, as smoothed-particle hydrodynamics (SPH) simulations are coupled with geophysical models to study both the immediate and long-term effects of planetaryscale impacts. In Chapter 1, a general introduction to the topic is given, placing planetary-scale impacts in the broader context of star and planet formation. In Chapter 2, the SPH code used to simulate planetary-scale impacts, SPHLATCH, is described in detail, including derivations of the background continuum mechanics theory along with descriptions of any practical developments applied to the code. In Chapter 3, the application of these SPH impact simulations to geophysical investigations is described. A particular focus of this chapter is the crust distribution inferred by an impact simulation; a novel scheme that estimates postimpact crust across a body directly from SPH simulations is described, as well as a more sophisticated approach involving a long-term mantle convection code. In the remaining chapters, these methods are applied in two scientific studies: Chapter 4 investigates the feasibility of an impactinduced Martian Dichotomy through a large suite of SPH simulations coupled with the crust-production scheme of Chapter 3, and finally, Chapter 5 presents a previously undiscovered impact regime that may explain the Sputnik Planitia region of Pluto.

Item Type: Thesis
Dissertation Type: Cumulative
Date of Defense: 9 September 2022
Subjects: 500 Science > 520 Astronomy
500 Science > 530 Physics
Institute / Center: 08 Faculty of Science > Physics Institute > Space Research and Planetary Sciences
Depositing User: Sarah Stalder
Date Deposited: 24 Oct 2022 07:29
Last Modified: 09 Sep 2023 22:25

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