Harry (Hap) McSween is Chancellor's Professor at the University of Tennessee. He has conducted research on cosmochemistry for more than three decades and was one of the original proponents of the hypothesis that some meteorites are from Mars. He has been a co-investigator for four NASA spacecraft missions and serves on numerous advisory committees for NASA and the US National Research Council. Dr McSween has written or edited four books on meteorites and planetary science, and co-authored a textbook in geochemistry. He is a former President and Fellow of the Meteoritical Society, a Fellow of the American Academy of Arts and Sciences, recipient of the Leonard Medal, and has an asteroid named for him.