Below is a description of my research interests, organized by methodology.
The gravity and topography of planets reflect the mass distribution within the planet and processes operating on the surface. As such, careful analysis can yield a wealth of information about interior and near-surface structure.
I analyze gravity and topography data in the spatial and spectral domains to understand the geophysical structure and history of planets. I am interested in how topography is supported. On the Moon, I have shown topography is likely compensated primarily by an Airy mechanism (variations in crustal thickness). On Mercury, I have addressed the inverse problem and derived Mercury's average crustal thickness.
I have also used gravity to identify hidden volcanic deposits on the Moon that are buried beneath brighter material.
LOLA and GRAIL datasets showing the topography (left) and gravity (right) of the Moon, respectively.
On Earth and on Mars, deposits of ice record information about the climate history of the planet. However, climate often is influenced by a complex interplay of factors which can be challenging to individually identify.
I developed techniques for analysis of ice deposits on Mars. I showed that if enough time is recorded in such a deposit, we can identify the influence of Mars' orbit on climate. I quantified the degree to which such an orbital signal can be detected in ice deposits.
I also study and model the glacial flow of ice. I showed that steep polar ice scarps on Mars flow relatively quickly, a process that may be linked to the avalanches we have viewed down their cliff faces.
Thermophysical modeling is an important part of understanding ice deposits. On Mars, I showed that proposed liquid water at the south pole requires a local heat source from subsurface magmatism to exist.
Volcanism and cryovolcanism
Volcanic activity, including icy cryovolcanic activity, reflect the thermal history of planets. For some bodies, volcanism is fundamentally connected with climate and orbital history. Lava flows (and cryolava flows) also shape the geomorphology of planetary surfaces.
I constrained lunar volcanic history using gravity data to constrain igneous deposits in the shallow subsurface. I used viscous flow models to constrain the cryovolcanic history and rates on Ceres. I am also developing models of lava emplacement to quantify the surface extent to which basaltic flows can cover on Mars.
Aerial image of the 2014–2015 Holuhraun basaltic eruption in Iceland taken during a field campaign I was a member of. The parameters in my models are constrained by terrestrial observations like these.
HRSC image of Louth crater on Mars, with a mound of exposed water ice. I argue analogous features of nitrogen ice exist on Pluto.
Voyager 2 image of Umbriel. I argue the bright annulus represents carbon dioxide ice that migrated to a favorable location.
When ices or volatiles exist at the surface of planet, they may act dynamically and migrate throughout seasons or years in response to changing conditions. Understanding how ices move around planetary surfaces can help us discover the origin of those volatile species and how they shape the geology we observe.
I quantitatively model volatile transport on airless bodies and compare to remote sensing or astronomical observations. I argued that a mysterious feature on Umbriel, a moon of Uranus, is best explained by the presence of carbon dioxide ice on the largest Uranian satellites.
I also am studying hills of ice in craters on Mars and Pluto. I argue these ice mounds are best explained as depositional outliers to large water and nitrogen ice deposits observed on the two planets.