Header J. Lawrence Smith Medal

The J. Lawrence Smith Medal is awarded every three years for investigations of meteoric bodies. The award includes a $50,000 prize. The award was established as a gift from Sarah Julia Smith in memory of her husband and has been presented since 1888.

Hiroko Nagahara, professor in the department of earth and planetary science at the University of Tokyo, is the recipient of the 2015 J. Lawrence Smith Medal.

Billions of years ago, before there were planets and moons, the Sun was surrounded by a swirling disk of gas, known as the solar nebula. Earth and the Solar System's other planets formed out of that disk. Evidence of what happened during those long-ago events is captured in some of the debris from space that falls to Earth—meteorites. Chrondrites are the most abundant type of meteorite. These stony chunks are distinguished by the presence of chondrules, but the source of those tiny, round grains of minerals has long been a source of debate. Some scientists have argued that the grains must have condensed directly from the solar nebula, while others thought that another mechanism must have been responsible for their formation. While still a graduate student, Nagahara shed light on this mystery, showing that some chondrules contained grains that had survived melting, which indicated that the those chondrules formed not from gas in the solar nebula but from the incomplete melting of an already-solid material. Nagahara went on to introduce condensation and evaporation experiments into chondrite science, successfully condensing in the lab minerals that are known to form chondrites, such as silicate and metallic iron. In later theoretical and experimental work, Nagahara and colleagues elucidated the processes underlying condensation and evaporation in the early solar nebula, helping to deepen our understanding of how Earth and the Solar System formed.


Hiroko Nagahara (2015)
For her work on the kinetics of evaporation and condensation processes in the early Solar System and her fundamental contributions to one of the most enduring mysteries in meteoritics, the formation of the chondrules that constitute the characteristic component of the most abundant group of meteorites.

Harry Y. McSween, Jr. (2012)
For his studies of the igneous and metamorphic histories of the parent planets of the chondritic and achondritic meteorites, with particular emphasis on his work on the geological history of Mars based on studies of Martian meteorites and spacecraft missions to this planet.

Robert N. Clayton (2009)
For pioneering the study of oxygen isotopes to unravel the nature and origin of meteorites, showing that meteorites were assembled from components with distinct nuclear origins.

Klaus Keil (2006)
For his pioneering quantitative studies of minerals in meteorites and important contributions to understanding the nature, origin, and evolution of their parent bodies.

John T. Wasson (2003)
For important studies on the classification, origin, and early history of iron meteorites and chondritic meteorites, and on the mode of formation of chondrules.

George W. Wetherill (2000)
For his unique contributions to the cosmochronology of the planets and meteorites and to the orbital dynamics and formation of solar system bodies.

Ernst Zinner (1997)
For his pioneering studies of the isotopic composition of circumstellar dust grains preserved in meteorites, opening a new window to the formation of the solar nebula.

Donald E. Brownlee (1994)

Robert M. Walker (1991)

A. G. W. Cameron (1988)

G. J. Wasserburg (1985)

Ralph B. Baldwin (1979)

John A. Wood (1976)

Clair C. Patterson (1973)

Edward Anders (1971)

Edward P. Henderson (1970)

John H. Reynolds (1967)

Harold C. Urey (1962)

Ernst J. Opik (1960)

Mark G. Inghram (1957)

Peter M. Millman (1954)

Fred L. Whipple (1949)

Stuart H. Perry (1945)

George P. Merrill (1922)

H. A. Newton (1888)

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