Sputnik Planitia as a Probe for Pluto’s Internal Evolution

Camille Adeene Denton, Purdue University

Abstract

Though we cannot directly characterize the internal structure of Pluto, its interior can be probed remotely by observing its response to impact-induced deformation. The formation and evolution of giant impact basins like Sputnik Planitia, Pluto’s massive 1200 x 1400-km-diameter impact basin, is a unique geologic process that links the dwarf planet’s interior structure to the basin’s morphology and overall longevity. Its large size, location, and relationship to tectonic features has led researchers to suggest that Sputnik Planitia preserves evidence of a large subsurface ocean, while possible antipodal features observed on Pluto’s far side raise questions of how stress waves from impact may have traveled through Pluto’s interior, which remains somewhat unconstrained. In this dissertation, I strive to understand the relationship between the formation and evolution of Sputnik Planitia and the thermal and mechanical structure of Pluto at a variety of scales. The years following New Horizons’ flyby of the Pluto system in 2015 have yielded more questions than answers about the state of Pluto’s interior, including the thickness and thermal structure of its ice shell, the possible presence of a liquid water ocean, and the composition of its rocky core. I use impact simulations to reproduce the unique physics associated with impact cratering and further investigate which internal structures are consistent with the cratering record, as well as finite element models to explore the postimpact evolution of Pluto’s largest impact basin and probe the mechanical and thermal structure of the ice shell in more detail. With these tools, I show that the formation and evolution of Sputnik Planitia is consistent with the presence of a hydrated core and thick subsurface ocean in Pluto’s interior. The results of this dissertation contribute to understanding the origin, evolution, and interior of Pluto as well as other icy moons, ocean worlds, and large Kuiper Belt Objects in our solar system, and has direct implications for future exploration of other such worlds in our solar system.

Degree

Ph.D.

Advisors

Minton, Purdue University.

Subject Area

Physics|Astronomy|Continental Dynamics|Geomorphology|Optics|Physical geography

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