Electronic Thesis and Dissertation Repository

Thesis Format

Integrated Article

Degree

Doctor of Philosophy

Program

Geophysics

Collaborative Specialization

Planetary Science and Exploration

Supervisor

Neish, Catherine D.

Abstract

Titan, Saturn’s largest moon, is an icy world harbouring a subsurface water ocean, a substantial atmosphere, and a flowing liquid on its surface. These distinctive characteristics give rise to complex chemical reactions on Titan, and also render it akin to Earth in terms of its landforms and processes. This positions Titan as a key target for studying prebiotic chemistry. NASA's fourth New Frontiers mission, Dragonfly, is poised to explore Titan’s surface in the 2030s. Dragonfly’s primary study site will be Selk crater, a relatively fresh impact crater located in Titan’s equatorial sand seas. Impact craters serve as valuable markers for comprehending how geological processes shape and modify Titan’s surface. The central theme of this thesis revolves around investigating the impact cratering process on Titan, using remote sensing and numerical modeling techniques. Specifically, we seek to use the morphology and morphometry of Titan’s impact craters to constrain the amount of erosion that has occurred there. Given Titan's similarities to Earth, we study terrestrial craters in radar images as analogues to constrain the crater population on Titan, and hence, its surface age. Furthermore, we explore the extent of erosion that may have occurred at Titan’s craters by simulating the formation of fresh craters on Titan. These simulations investigate the influence of the thermal properties of methane clathrates on crater depths. These studies collectively contribute to a more nuanced understanding of the impact cratering process on Titan. The Dragonfly mission, in its exploration of Selk crater, will provide further insights into Titan’s geological history and subsurface structure, refining the surface age and erosion constraints presented in this work. To support future operations in Selk crater, we conducted an analogue mission simulation using an Unoccupied Aircraft System and applied lessons learned to the currently planned strategies for Dragonfly.

Summary for Lay Audience

Titan is Saturn's largest moon and the second largest moon in our solar system. It has a thick atmosphere and liquid flowing on its surface. In this sense, it is very similar to our planet Earth. However, Titan is a very cold place with an ice shell on its surface and an underground water ocean. These characteristics combine to sustain a water cycle much like on Earth, but with methane as the liquid. Weather on Titan works to reshape the planet’s surface, especially the impact craters seen there. Impact craters are bowl-shaped depressions that form when asteroids travelling at high speeds collide with a planetary surface. These craters are good markers for studying how the surface of Titan changes over time. This work focuses on better understanding these impact craters and the information they provide about Titan. First, we study these craters to figure out how many might have been completely erased due to the erosion on Titan. This helps us to figure out how old Titan’s surface might be. We, then, model what fresh craters might look like to estimate the level of erosion on Titan. Lastly, we examine drone images of a planetary analogue site on Earth to find strategies to better explore the Selk crater on Titan with NASA’s Dragonfly spacecraft in the future.

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