Constraining the Parameter Space of Rocky Planet Interiors and Atmospheres Using Parameterized Mantle Convection Models

Abstract

As the search for life beyond Earth continues, characterizing the potential habitability of exoplanets as well as observing biosignatures in their atmospheres has become increasingly important. As these assessments ultimately derive from properties of the planet’s atmosphere, the geophysical and geochemical processes that occur in a planet’s interior and source these atmospheric gases must be better understood. Exoplanets provide a new realm of geoscience, such as crustal recycling on a non-tectonic plate planet, that requires generalization of models of interior evolution that were previously calibrated to Earth.In Chapter 2 of this thesis I describe the development of an interdisciplinary model of atmosphere-interior interactions to quantify the effects of a planet’s interior on its atmosphere and track the flow of major atmospheric molecules across a planet’s reservoirs over its history. In Chapter 3 I use my model to simulate Venus and retrieve possible evolutionary histories of the planet. I also discuss possible observations that could be made by future Venus missions to discriminate between possible evolutionary histories. In Chapter 4 I examine the inter- related planetary processes that shape its evolution (the “whole-planet coupling" approach). In doing so I demonstrate that self-consistently modeling atmospheric escape and surface outgassing is critical to the thermal evolution of a rocky planet, as the loss of an atmosphere to space results in lower surface pressures, facilitating water outgassing that in turn influences convection in the planet’s interior. Finally, in Chapter 5 I discuss additions that could be made to my model and how they could aid in testing hypotheses about planetary evolution.