From 1983 to 1988, he was the project engineer for the NASA Scatterometer. He was principal investigator for an airborne rain mapping radar, an airborne cloud mapping radar, an experiment using spaceborne imaging radar to study rainfall effects on ocean roughness, and the development of an airborne active/passive microwave system for ocean salinity and soil moisture sensing. From 1997 to 2001, he managed the New Millennium Program, designed to flight-validate key technologies that bring significant benefits to future science missions.
He became deputy director of JPL's Solar System Exploration Program Directorate in 2001 and deputy director for the Mars Exploration Directorate in 2004. He is currently also the Mars Exploration Program Manager.