University of Pittsburgh
September 24, 2002

International Planetary Scientists Converge on Pitt for Symposium Today and Tomorrow Event honors retired Pitt researcher Bruce Hapke, whose once-ignored space weathering theory was vindicated 25 years later, in 2000

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September 20, 2002

PITTSBURGH—Scientists from the remotest parts of the planet will converge on Pittsburgh for the two-day "Solar System Remote Sensing Symposium," beginning today in the University of Pittsburgh's University Club, 123 University Place, in Oakland.

Cosponsored by Pitt, the Lunar and Planetary Institute, NASA, and the Spectroscopy Society of Pittsburgh, the event will honor Pitt Emeritus Professor of Geology and Planetary Science Bruce Hapke, whose theory of space weathering—at first ignored by the scientific community when he presented it in 1975—was finally accepted in 2000, 25 years later.

"The subject of space weathering interests planetary scientists who use remote sensing because it causes major changes in the optical properties of the surfaces," says Hapke. "Space weathering is the cumulative effect of the physical and chemical changes on material exposed on an airless body."

Academic, government, and private industry researchers from the United States, Russia, Ukraine, Finland, Japan, Italy, and France will present papers in what appears to be an international "Who's Who" of planetary scientists. According to Pitt Emeritus Professor of Geology and Planetary Science William Cassidy, a long-time colleague of Hapke, many of the papers being presented reflect Hapke's work.

"Bruce was a member of the first group of scientists to receive lunar samples during those exciting times when the world was transfixed by the images of astronauts standing on the moon," Cassidy says. "Studying these samples over a period of years, Bruce and his students unraveled the natural processes that cause the lunar surface to become darker over time, and, from an understanding of these processes, predicted the physical state of the surfaces of grains exposed on the surface of the moon.

"These principles have now been found to apply to all airless bodies in the solar system. The general process, called space weathering, affects our interpretation of remote sensing observations of the surfaces of Mercury and the asteroids," Cassidy adds.

The symposium was organized by Cassidy and a committee composed of Deborah Domingue, Applied Physics Laboratory, Johns Hopkins University; Robert M. Nelson, Jet Propulsion Laboratory; Carle Pieters, professor in the Department of Geological Sciences at Brown University; Yurij Shkuratov, Kharkov Astronomical Observatory in Ukraine; Ann Sprague, senior research associate, lunar and planetary laboratory at the University of Arizona; Joseph Veverka, professor and chair of the Department of Astronomy at Cornell University; Faith Vilas, a planetary astronomy scientist at NASA Headquarters; and Robert Witkowski, a volunteer at the University of Pittsburgh.

A list of participating institutions follows.


The University of Helsinki


Institut d'Astrophysique Spatiale

Laboratoire de Planétologie de Grenoble

Observatoire Midi-Pyrénées


INAF – Osservatorio Astronomico di Torino



Kobe University

Nishimatsu Construction Co.

Osaka University

The University of Tokyo



Space Research Institute, Moscow


Kharkov Astronomical Observatory

United States


Jet Propulsion Laboratory, at California Institute of Technology

NASA Ames Research Center, Moffett Field, Cal.

NASA Goddard Space Flight Center, Greenbelt, Md.

NASA Johnson Space Center, Houston, Tex.


University of Arizona, Lunar and Planetary Laboratory

Arizona State University

Bloomsburg University Department of Geography and Geosciences

Brown University Department of Geological Sciences

University of Colorado, Boulder

Cornell University Center for Radiophysics and Space Research

Grays Harbor College, Aberdeen, Wash.

Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa

Hawaii Institute of Geophysics and Planetology, University of Hawaii at Honolulu

Ithaca College

Johns Hopkins University

Northwestern University

University of Tennessee Planetary Geosciences Institute

University of Virginia

Wellesley College

Washington University, McDonnell Center for the Space Sciences


Applied Physics Laboratory, Laurel, Md.

Applied Coherent Technology, Herndon, Va.

L3 Com Analytics Corporation, of Vienna, Va.

Science Applications International Corporation, Chantilly, Va.

Southwest Research Institute, Boulder, Co.

Space Science Institute, Boulder, Co.