Impact cratering has been recognized as an important geologic process for only the last few decades. As recently as 1950 most astronomers believed that the lunar craters were giant volcanos, and all but a few geologists derided the idea that the earth's surface has been scarred by impact structures kilometers in diameter. A vigorous program of planetary exploration in the Apollo era and continued geologic research on earth has changed these views profoundly. It is now recognized that the cratered landscapes of the moon, Mercury, Mars, and many of the solar system's satellites are sculptured predominantly by repeated impacts of all sizes. More than 100 impact structures with diameters ranging up to 140 km have been identified on earth.

The study of impacts on planetary surfaces and the corresponding geological processes is another direction of our research group. Students Li Huacheng, myself, and collaborator Professor YUE Zongyu have made steady progress.