PhD in Geological Sciences, Brown University. 1992-2000, various senior scientist positions, Jet Propulsion Laboratory. 2000-12, Vice-President, Proxemy Research. 2013-16, Chief Scientist, NASA (2013-2016). Honorary Professor, Department of Earth Sciences, University College London; Senior Scientist, Applied Physics Laboratory, Johns Hopkins University. Co-Chair, World Economic Forum Global Future Council on Space Technologies. Associate Member, Cassini Mission to Saturn Radar Team; proposed a mission to NASA to land a boat on a sea on Titan. Fellow: Geological Society of America; Explorers Club.