Current Research Projects

Here is a selection of the projects I'm currently working on. I'm always looking for students who want to help out, so contact me if you're interested!

Ganymede

• Global tectonics: One of the primary mysteries of Ganymede is the origin of the grooved terrain that covers the majority of its surface. I am currently finishing a decade-long project to understand the strain history represented by the grooved terrain, and compare it to theoretical models for the origin of the stress that drove grooved terrain formation.

• Global geologic map: We are finishing the global geologic map of Ganymede, in collaboration with Wes Patterson (APL), Jim Head (Brown), Bob Pappalardo (JPL), Louise Prockter (APL), and Baerbel Lucchitta (USGS). The results of this project were recently published in Icarus, and the map sheet is to be submitted for publication by the US Geological Survey. Students who have contributed to this project include Karrie-Sue Farrar '03 and Jonathan Kay '08.

• Local-scale tectonics: We are working to understand individual groove lanes observed at high resolution by Galileo, and interpreted as sets of normal faults. We have been measuring the strain accommodated by these features and linking that to the geometry of the faults. A current collaboration with Darrell Sims (SwRI) is helping to link the morphology of the interacting normal faults to analog models in the laboratory. Robert "Louie" Michaud '08 has contributed to this project.

• Compositional mapping: Together with Karl Hibbitts (APL) and Gary Hansen (U. Washington), I am merging data from the Near-Infrared Mapping Spectrometer instrument on Galileo with geologic maps of Ganymede, to better understand compositional differences between different surface features.

Enceladus and Dione

• Local-scale tectonics: The numerous faults cutting across the surfaces of Enceladus and Dione are similar in many respects to the faulting observed on Ganymede, and we are using the same tools to investigate them. In addition, we discovered chains of pits on the surface of Enceladus that may be related to regolith drainage into dilational normal faults. Robert "Louie" Michaud '08 and Noemie Goff-Pochat '10 have contributed greatly to this project.

Titan

• Fluvial erosion: The discovery of river channels on Titan has led to a collaboration with Leonard Sklar (SFSU) and his graduate students Peter Polito, Beth Zygielbaum, and Kim Litwin, in order to consider the rate at which ice can be eroded by moving sediment particles in a methane stream. We have been testing the mechanical properties of polycrystalline ice "bedrock" at Titan temperatures and considering the similarities with erosion in terrestrial bedrock streams. Megan O'Sadnick '08 worked on applying our results to also consider the ablation of glacier ice by wind-driven particles.

Europa

• Chaotic terrain: I am fascinated by the areas of chaotic terrain on Europa's surface, and recently authored a book chapter summarizing the state of knowledge and outstanding issues about chaotic terrain. At Wheaton, Jason Goodman and I have been thinking about the interaction between plumes of warm water rising from the seafloor and the effects those plumes would have on the overlying ice. The origin of chaotic terrain is still a major unsolved puzzle.

Pluto

• Amy Barr (SwRI) and I have been working on modeling the response of Pluto's interior to the tidal evolution of the Pluto-Charon system, in order to predict what kind of world the New Horizons mission will find when it flies by in 2015. Based on our research, I think Pluto will show signs of past tectonic activity.