Below are descriptions of our research interests, organized by methodology.
Gravity science and planetary interiors
The gravity and topography of planets reflect the mass distribution within the planet at a variety of depths. As such, careful analysis can yield a wealth of information about deep interior and near-surface structure.
We analyze gravity and topography data to understand the interior structure and geophysical history of planets. On the Moon, we have shown topography is likely compensated primarily by variations in crustal thickness. On Mercury, we have derived Mercury's average crustal thickness. We are also studying the best paths forward for the collection of new gravity data through spacecraft missions at worlds beyond the Earth-Moon system.
LOLA and GRAIL datasets showing the topography (left) and gravity (right) of the Moon, respectively.
Ice deposits record information about the climate history of a planet. This climate record often is influenced by a complex interplay of factors which can be challenging to decipher.
We develop techniques for analysis of ice deposits. On Mars, we have studied the polar ice sheets, quantifying the degree to which an orbital signal can be detected and the degree to which glacial flow is important in interpreting the climate record. We have used thermophysical modeling to show that any liquid water under these ice sheets requires a local heat source from 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 also shape the geomorphology of planetary surfaces.
Cryovolcanism is especially a research focus of ours. We have used spacecraft observations and computer simulations of viscous flow to constrain cryovolcanic history and eruption rates on dwarf planet Ceres. We are currently in the process of similar studies of cryovolcanism on other planets and moons. We have also quantified basaltic volcanic history on the Moon using gravity data to constrain buried lava flows in the shallow subsurface.
Aerial image of the 2014–2015 Holuhraun basaltic eruption in Iceland taken during a field campaign we participated in. The parameters in our models are often constrained by terrestrial observations like these.
HRSC image of Louth crater on Mars, with a mound of exposed water ice. We argue analogous features of nitrogen ice exist on Pluto.
Voyager 2 image of Umbriel. We 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.
We quantitatively model volatile transport on airless bodies and compare to remote sensing or astronomical observations. We 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. We analyzed mounds of ice in craters on Mars and Pluto and concluded they are depositional outliers to larger water and nitrogen ice sheets observed on the two planets.