I am interested in how planets and satellites have evolved to their current states, and what explains the spectacular planetary diversity we see. For instance, why do the Earth and Ganymede possess magnetic fields at the present day, while Venus and Europa do not? Why is tiny Enceladus geologically active, while its neighbour Mimas is dormant? To answer questions like this requires a combination of spacecraft observations and geophysical models.

I am spending a lot of my time using observations of icy bodies to work out their current state and history. For instance, the ridges that we see on Europa, Triton and Enceladus might be a consequence of back-and-forth motion driven by tides. Likewise, the large extensional faults we see on Pluto may be a consequence of its having a refreezing ocean beneath the surface. As a member of four instrument teams on NASA’s Europa Clipper spacecraft, I am excited to see how new observations will improve our understanding of this particularly interesting moon.

I am also interested in what cosmochemical measurements of isotopes tell us about how the terrestrial planets formed. Some isotopes (such as Hf) have convenient decay times that tell us about processes like core formation. Others (such as Cr,Ti,Zn,Mo) are passive tracers of the two different reservoirs from which all solar system materials are made. Combining isotopic evolution with the output from accretion simulations allows us to probe the details of how the terrestrial planets were put together.

This is just a sample of the kind of geophysical problems I’m interested in; to get a more complete idea, take a look at my list of publications.