Observation and modeling of the spatial and velocity distribution of neutral and ionized cometary gases and dust
Development of time-dependent multidimensional multispecies fully kinetic models for cometary and planetary satellite atmospheres using Direct Simulation Monte Carlo methods
Planetary satellite atmospheric structure, escape and interaction with planetary magnetospheres
Cometary X-ray observations and study of the excitation mechanism

Honors, Awards and Accomplishments

Member, College of Engineering Research Strategy Committee
Distinguished Research Scientist Award, U-M, 2003
Outstanding Research Scientist Award, U-M, College of Engineering, 1996-1997
Editor's Letter of Commendation, planetary science journal Icarus, 1991 and 1992
Co-Investigator, Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) team, European Space Agency's Rosetta mission to comet P/Wirtanen
Team Member, Visual and Infrared Mapping Spectrometer instrument, NASA's Comet Rendezvous Asteroid Flyby Mission
Guest Observer, International Ultraviolet Explorer satellite
Guest Observer, Hubble Space Telescope (HST) involving ultraviolet spectroscopy and imaging of the 1996 bright comet Hyakutake
Guest Investigator, observing campaign of the Solar Wind Anisotropies (SWAN) instrument, Solar and Heliospheric Observatory (SOHO) satellite (SWAN pictures)
First applied Monte Carlo models to study the complicated geometries of free-flow region of cometary atmospheres
Provided one of the early sets of cometary radical scale lengths for use in determining gas species production rates in comets
First quantitative observations and analysis of the spatial distribution of water and carbon monoxide ions in the heads and inner tails of comets
With a colleague, provided the complete self-consistent description tying together the underlying physics of the dynamics of the inner cometary coma outflow, dominated by water photochemistry, with the appearance and velocity distribution of the hydrogen coma of comets, and how these change with the size of the comet and its distance from the sun
Part of the group that was the first to simulate cometary X-ray production by charge exchange excitation
With colleagues, demonstrated conclusive evidence from ground-based images of comet Hyakutake that fragments of the nucleus traveling down the tail were providing an extended source of gases which collided with the main coma outflow

Professional Service

Sigma Xi
Director, Research Experiences for Undergraduates (REU), funded by NSF, and providing real-world university research experience for undergraduate majors in mathematics, the physical sciences and engineering
Editor, Icarus, official journal, Division for Planetary Sciences, AAS
American Astronomical Society (Division for Planetary Sciences)
American Geophysical Society
International Astronomical Union
American Association for the Advancement of Science
European Geophysical Society
Member, numerous NASA panels including Planetary Systems Science Management Operations Working Group, CRAF Peer Review Panel, International Halley Watch/PDS Peer Review Panel, NASA Planetary Astronomy Peer Review Panel, Hubble Space Telescope Planetary Science Review Panel

Updated: 2007-10-15