Geology & Earth Science

Geology & Earth Science Experts

William K. Hartmann

Senior Scientist
Department of planetary Sciences
Planetary Science Institute
New Zealand


In 1962, Dr. Hartmann was lead author, with G. P. Kuiper, in the first recognition of multi-ring impact basins with concentric and radial structure on the moon, including the discovery of the Orientale basin bullseye on the east limb of the moon. Such basins have since been recognized on most cratered planets and satellites. This was first recognized on "rectified photos" in which telescopic photos of the moon were projected on a globe. In 1965 he used crater counts on the moon and Earth to predict successfully that the lunar lava plains have an age of "about 3.6 x 10 9 years" (Icarus, 4:164). The date was confirmed five years later with Apollo samples from the moon. This work helped pioneer the usefulness of craters for interpreting planet surface ages; the 1966 Nininger Meteorite Award was shared for this work. In 1971-72 Dr. Hartmann was a co-I on the Mariner 9 mission which first mapped Mars in detail. With Bruce Murray, Carl Sagan, and others on the imaging team, they discovered Mars' dry river channels, volcanoes, and other features. In 1974-5, he was lead author, with D. R. Davis, of what has become the most widely accepted theory of the origin of the moon, by impact of giant planetesimal at the close of the planet-forming period. See PSI's Origin of the Moon page. In the 1980s, he worked with D. P. Cruikshank, David Tholen, and others to carry out observations at Mauna Kea Observatory on the relationships of asteroids and comets, with D. P. Cruikshank, D. Tholen, and others. Our 2-color diagram of visual and infrared colors showed the close spectroscopic relation of comets and outer solar system asteroids. Bright, icy satellites are in the lower left corner (bluish-white colors), while comets and carbonaceous types of asteroids ("C, P, and D" taxonomic types with brownish-black colors) fall in the upper right corner. They were probably the first to recognize that comets have similar black surface materials (4% reflectivity) to those on outer solar system asteroids. This proposal was controversial at the time, but confirmed a few years later by the Giotto probe at Halley's comet. Their program also yielded proof that Trojan asteroid 624 Hektor was one of the largest highly elongated bodies in the solar system, and the discovery that "asteroid" 2060 Chiron had erupted and turned into a comet. Generally, our work aided the recognition that comets and asteroids could no longer be considered as independently as had been traditional.

Research Interest

Dr. William K. Hartmann's interest in general span the origin and evolution of the planetary system and planetary surfaces. Special interests have included of evolution of surface features, craters, and interplanetary bodies. Currently, he is concentrating his research efforts on Mars Global Surveyor's new data from Mars, as part of his work with the MGS imaging team. The results show the importance of windblown dust in blanketing and shaping much of the topography at 10-meter scale.

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