Bachelor of Arts in Physics, 1982, Swarthmore College; Bachelor of Arts in Mathematics, 1984, Master of Arts 1990, University of Cambridge; M.Phil. History and Philosophy of Science 1986, University of Cambridge, Cambridge, England; Doktortitel in Astronomy (Planetary Science) von der Cornell University, 1991; Semifinalist bei der Astronautenauswahl der NASA-Gruppe 16; derzeit Co-Director of Stanford's Center for International Security and Cooperation und Associate Professor im Department of Geological and Environmental Sciences.