Interior Evolution of Planetesimals, Asteroids and Dwarf Planets

Some asteroids and dwarf planets are relics of the planetary building blocks ofthe early solar system. They record ancient planetary interior processes and serve as natural laboratories for investigating the solar system’s history. I model the thermal evolution of these bodies and show how that affects their composition, which I present in four case studies.

In Chapter 2, I demonstrate that the paleomagnetic record in carbonaceous chondrite meteorites is a natural consequence of planetesimals forming in the solar nebular field between ⇠2.5 and 4 million years after the start of the solar system. Primitive carbonaceous asteroids, perhaps like (2) Pallas, were once planetesimals that experienced sufficient heating in the early solar system to melt water ice and undergo aqueous alteration, but not enough to demagnetize rocks.

In Chapter 3, I show how core formation and solidification processes can lead to the eruption of molten core metal, termed ferrovolcanism. I argue that this process could have occurred on (16) Psyche, and that NASA’s Psyche mission could measure remanent magnetic fields recorded in ferrovolcanic dikes that solidified while (16) Psyche had a core dynamo.

In Chapter 4, I assess the dynamic habitability of (1) Ceres by calculating the thermodynamic chemical energy available for microbial life. In this model, I evaluate the temperature and composition of Ceres’s interior over time, tracking Ceres’s ocean’s redox state and habitability.

Finally, in Chapter 5, I evaluate Pluto’s history, showing that it likely either does not have an ocean or only retains a thin residual ocean today. The model includes an approximation of the breakdown of organic material, which allows for the release of methane and carbon dioxide that can be incorporated into ice shell clathrates. The presence of insulating clathrates is likely insufficient to maintain a thick ocean.

My thesis illustrates how the thermal evolution of the interiors of primitive bodies controls the compositional cycling of these worlds. I demonstrate how the models can be used to interpret meteorite data and create testable hypotheses for future spacecraft missions.