I specialize in studying the properties and evolution of the surfaces of small solar system bodies, with a particular interest in impact crater dominated terrains. My work includes the computation of gravitational /rotational asteroid surface conditions, and the analytical and numerical modeling of surface development, regolith growth, and cratering on these objects. This modeling work is compared directly to observations, either returned by spacecraft or gathered by Earth-based radar experiments, including such properties as overall shape, spin, topography, density, indications of regolith and boulders, and cratering records.
- Described the erosional process whereby spin and gravity combine to minimize topographic relief on asteroid surfaces (Icarus, 2014, Icarus, 2019)
- Determinted the surface properties of comet 9P/Tempel 1 via measurements of the crater produced by Deep Impact (Icarus, 2013)
- Solved the long-standing question of how crater density equilibrium is reached on heavily-cratered terrains (Icarus, 2009)
- Determined the density of comet 9P/Tempel 1 via the expansion rate of the ejecta plume produced by Deep Impact (Icarus, 2007)
- Linked the paucity of small craters on asteroid 433 Eros to the effects of impact-induced seismic shaking (Science, 2004, Icarus, 2005)
- Extracted surface features of Saturn's moon Titan hidden within the Orange-fliter images taken by Voyager 1 (Icarus, 2004)