"American planetary scientist" . . . "1953Z"^^ . "Christensen, Phil"@en . . . . . "Philip Russel Christensen is a geologist whose research interests focus on the composition, physical properties, processes, and morphology of planetary surfaces, with an emphasis on Mars and the Earth. He is currently a Regents' Professor and the Ed and Helen Korrick Professor of Geological Sciences at Arizona State University (ASU)."@en . "Phil Christensen"@en .