Below are descriptions of our research interests – the categories often overlap!
Planetary structure and interiors
A planet's gravity field, topography, and internal heat can reveal abundant insights into that world's geophysical history and interior structure.
We analyze and model these three types of data to understand deep structure, near-surface structure, and effects on surface features. On the Moon and Mercury, we have considered gravity and topography datasets in tandem to constrain crustal thickness and the way topography is supported. On Mars and Triton, we have identified connections between internal heat and melt of surface ices. 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.
Bright deposits in Occator crater (left) and the mountain Ahuns Mons (right), on Ceres. We have studied these features, both of which have been proposed to cryovolcanic, using a variety of datasets and techniques. Data and images come from NASA's Dawn mission.
Volcanism and cryovolcanism
Volcanic activity, including icy cryovolcanic activity, reflects the thermal history of planets. For some bodies, volcanism is also 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.
Ices on planetary surfaces may form thick deposits over many years, recording information about the climate history of their world. Ices and volatiles may also migrate over the course of shorter timescales in response to changing conditions, and understanding how they move around planetary surfaces can help us discover their origin or understand how they shape landscapes.
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. On icy satellites, we use volatile transport models, and have argued that a mysterious feature on Uranus' moon Umbriel is a carbon dioxide ice deposit. We are currently applying these techniques to other outer solar system bodies.
HiRISE image showing icy stratigraphy on Mars (upper left). Sample result of our 3D flow simulations for a polar ice crater on Mars (left). Voyager 2 image of Umbriel (upper right), showing bright feature on top we proposed is CO2 ice.