Callisto Crater Chains. I wanted to depict the impact of a Shoemaker-Levy 9 like comet on the Jovian moon Callisto. A long standing mystery from the first flyby of the Voyager spacecraft in the late 1970's was the discovery of crater chains, called ``Catena'' on Callisto and Ganymede. Crater chains found elsewhere were found to be secondary impacts from a large impact structure and tended to point back to the source crater, but that was not found to be the case on Callisto. Finally, in March 1993, Carolyn Shoemaker along with her husband Gene and David Levy discovered their now famous comet which was quickly confirmed to be a string of over 20 individual nuclei that resulted from the tidal breakup of the progenitor body and which impacted on Jupiter in July 1994. After working on and thinking about the problem without a satisfactory answer since the Voyager days, Paul Schenk of the Johnson Spaceflight Center in Houston figured he might never find an answer to these mysteries. Shortly after their discovery, the S-L 9 images reminded Jay Melosh of the Lunar and Planetary Laboratory in Tucson Arizona of the Callisto crater chains and a discussion I had with him one afternoon in April 1993 got the ball rolling on the answer. Melosh designed a tidal breakup model which he used in collaboration with Paul Schenk to describe the crater chains on Ganymede and Callisto. Melosh and I collaborated on applying the model to the observations of S-L 9 that I had made which resulted in a direct measurement of the size of the original object which broke up to form the doomed comet. We found that the object must have been only 2 kilometers in diameter. Later work by Eric Asphaug and Willy Benz and others have confirmed the size estimate and filled in more details. This painting was started in December, 1995 and completed on March 31, 1996 and is a 24 by 24 inch acrylic on foam board. It is intended to be viewed either as shown here or rotated clockwise 45 degrees from this view.

Last update: January 29, 1997