Mark Thiemens, a former dean and professor of chemistry and biochemistry at UC San Diego, has won the most prestigious prize awarded in the field of meteoritics — the scientific discipline concerned with the study of solar system origin, evolution and history.

Thiemens, who served for the past 16 years as the founding dean of the Division of Physical Sciences, was announced as the winner of the Leonard Medal for 2017 at the annual meeting in Berlin, Germany of the Meteoritical Society, the International Society for Meteoritics and Planetary Science. The prize was established in 1962 to honor the first president of the society, Frederick Leonard.

Thiemens, who stepped down as dean last month to spend more time on his research activities, is the fourth in a long line of prominent chemistry professors at UC San Diego to receive the Leonard Medal. All were leaders in their respective fields and all, coincidentally enough, started their careers at the University of Chicago, where Thiemens did his postdoctoral research.

The three previous recipients were Nobel-Prizewinning chemist Harold Urey, the father of planetary science who won the Leonard Medal in 1969; James Arnold, the first chair of UC San Diego’s chemistry department who was one of the first scientists to analyze the lunar samples brought back by the Apollo mission and who won the medal in 1976; and Hans Suess, a prominent physical chemist who collaborated on the development of the shell model of the atomic nucleus and the isotopic abundances of the elements. Suess, who co-authored with Roger Revelle a scientific paper that made the prediction of carbon dioxide rise in the Earth’s atmosphere before measurements were made, received the Leonard medal in 1977.

Thiemens received his undergraduate degree in chemistry at the University of Miami and his Ph.D. from Florida State University. He came to UC San Diego in 1980 following a postdoctoral fellowship at the Fermi Institute of Nuclear Studies at the University of Chicago. In his initial years at UC San Diego, he made discoveries that overturned conventional theories about the formation and evolution of the solar system.

During his research career at UC San Diego, Thiemens developed new techniques of understanding the composition of the early atmosphere of the Earth, life’s imprint and the evolution of Mars. In 2006, the minor planet center at the Harvard-Smithsonian Center for Astrophysics, the clearinghouse for naming asteroids, designated a minor planet orbiting the inner part of the main asteroid belt (7004) Markthiemens in honor of his work with meteorites and extraterrestrial materials.

Thiemens is a member of the National Academy of Sciences, the American Academy of Arts and Sciences, a two-time winner of the Alexander von Humboldt Award and was awarded the prestigious E.O. Lawrence Award from the U.S. Department of Energy in 1998 and the 2009 V.M Goldschmidt Medal of the Geochemical Society. He is also an elected Fellow of the American Geophysical Union, Geochemical Society and the European Association of Geochemistry.

Kim McDonald
UCSD Director of Science Communications
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