I am primarily interested in the global-scale problems concerning the terrestrial planets and icy moons of the solar system. I wish to understand the physical processes that control the evolution of these objects. I focus on geodynamic approaches to these problems, such as mantle convection, elastic flexure, and viscoelastic relaxation. My goal is to look at the big picture; to understand why the planets and moons look the way they do, what they were like early in their history, and how they evolved to their present state.
My research falls in the realm of Planetary Geodynamics. Geodynamics is the study of the internal movements of the Earth. It involve processes such as mantle convection, tectonics, and deformation of earth materials. We need to consider rheology (material properties), heat transfer, and even the gravitational and geoid response to all these internal dynamics. Although most geodynamicists study the earth, I investigated these processes in the context of other planetary bodies, particularly Mars and Enceladus, a moon of Saturn.
I am a postdoc at the Applied Physics lab at Johns Hopkins University.
I've just moved here from the Earth and Planetary Sciences department at the University of California at Santa Cruz, working with Francis Nimmo who can sometimes be difficult to find.
Here is a pdf version of my Curriculum Vita. A list of publications with links to pdfs can be found at the bottom of the page.
These are some of the specific projects I've been working on. I've given just a brief summary below. For more information on any topic, click on the title to be taken to another page dedicated to that project.
There's a 20 km high ridge around most of Iapetus. How did that get there? That's my current project
During the Noachian there were several impacts large enough to create basins at least 1000 km across. Fifteen of these impacts occurred within a 100 Myr period. At around the same time, the global magnetic field of Mars disappeared. The five youngest giant basins are de-magnetized. Recently I've been working with Rob Lillis and Michael Manga at Berkeley investigating a causal connection between these events. The magnetic field is generated by a geodynamo, caused by turbulent core convection. The vigor of core convection is controlled by the cooling rate. While impacts do not generally affect the core directly, they can impart a lot of heat into the mantle. The largest impacts, such as Utopia, heat the mantle so much that the heat flow out of the core drops significantly. It's possible that mantle heating due to giant impacts is responsible for the death of the martian dynamo during the mid-Noachian. Utopia, the largest basin, is also the first clearly demagnetized basin.
I've been working on 3D tidal heating and convection models for icy satellites. In particular, I've been focusing on Enceladus (en-SEH-la-dus), a small-to-medium size moon of Saturn. The satellite is named after a giant in ancient Greek mythology, believed to be buried under Mt. Aetna. If you use the Italian pronunciation, you get "en-che-LA-dus", hence the image to the right. Enceladus is a particularly interesting target, given the south polar thermal anomaly, showing massive heat flux and vapor escape from a world thought to be dead before Cassini discovered otherwise. The popular idea at the moment is that orbital energy from Enceladus' eccentric orbit about Saturn is being dissipated as heat in the ice shell. But is tidal heating sufficient to explain the observations? And are there other ways of doing it? That's what I'm testing.
Large-scale structures on Mars: The Hemispheric Dichotomy and the Tharsis Rise.My recently finished thesis work focussed on Martian Geodynamics. I find this field so interesting, because we can answer important first-order questions about the shape of Mars. Why is there a hemispherical dichotomy? Why is it oriented north-south? Why is Tharsis so big? How active was the planet in the past? Topography and gravity data from the many spacecraft missions are the primary observations we can use to study these problems. I developed theoretical and computational models to explain these observations. Just by looking at the MOLA topography map below, you can tell that something is up.
Courtesy: NASA/GSFC