"It's a great honor to join such a distinguished list of awardees," said Clayton, the Enrico Fermi Distinguished Service Professor Emeritus in Chemistry and Geophysical Sciences at the University of Chicago.
Clayton, 75, has pioneered the use of oxygen isotopes, chemical fingerprints found in meteorites and lunar rocks, in understanding the processes that formed the planets and asteroids early in the history of the solar system. His studies have provided surprising evidence supporting the theory that the moon was part of the Earth until a collision with another planet-sized object blasted them apart, and have helped identify the first lunar meteorite.
"Bob Clayton's great achievements have given us a fascinating glimpse into the early years of our solar system. He is a wonderful University of Chicago scientist, and a truly fine person. I am absolutely delighted by the news of this award, which he so richly deserved," said Robert Fefferman, Dean of the Physical Sciences Division at the University of Chicago.
Reinforcing those comments was David Rowley, Chairman and Professor in Geophysical Sciences at the University of Chicago. "It's hard to imagine there's anyone else more deserving than Bob of this recognition," Rowley said. "He simply does what he enjoys doing and not for the accolades."
Most of Clayton's lunar research stemmed from his examination of approximately 300 samples collected during all six Apollo moon landings from 1969 to 1972 and during the Soviet Luna 16 and 20 robotic missions. But his laboratory also has become well known as a clearinghouse for the analysis of strange meteorites.
While studying meteorites with colleagues at the Fermi Institute, Clayton in 1973 discovered that the chemistry of oxygen in the early solar system was fundamentally different from that known on Earth. This led to the recognition of the importance of photochemistry (the interaction of light and chemicals) in the formation of the planets and to a new prediction of the abundances of oxygen isotopes in the sun. This prediction will be tested by analysis of the solar wind in NASA's Genesis mission.
Clayton and his colleagues also identified the first lunar meteorite in 1983. And by studying martian meteorites they showed in 1992 that Mars probably once had water on its surface or in its atmosphere. More recently, he was a member of a team that in 2000 established the Tagish Lake meteorite from Canada as perhaps the most pristine sample of the solar system ever studied.
Clayton joined the University of Chicago faculty in 1958 and served as director of the University's Enrico Fermi Institute from 1998 to 2001. He officially retired in 2001, but still pursues an active research program. His honors include membership in the National Academy of Sciences. He also is a fellow of the American Academy of Arts and Sciences, the Royal Society of Canada, the Royal Society of London and the American Association for the Advancement of Science. An asteroid also has been named in his honor.
Congress established the National Medal of Science in 1959. The 2004 awards bring to 13 the number of University of Chicago faculty members who have received a National Medal of Science.
High-resolution photographs of Prof. Clayton are available upon request.