He received his Ph.D. in Planetary Sciences from the University of Arizona in 1994, with researching the structure of hazes in the atmosphere of Saturn's moon Titan, and making observations that showed the atmosphere to be transparent in the infrared. After working with Peter Smith to map Titan's surface with infrared Hubble Space Telescope images, he joined the Imager for Mars Pathfinder team as a postdoc. Despite a detour as a postdoc on Mars Polar Lander until it crashed, he remains active in Mars Exploration. For MER, in addition to acting as a downlink lead for Pancam, he is one of the Atmospheric Science Theme Group leads. In between MER downlinks, he is the Instrument Co-Investigator responsible for the Surface Stereo Imager on Phoenix, the next mission to land on Mars, and is on the camera team for Mars Science Laboratory.