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Eugene Merle Shoemaker

Eugene Merle Shoemaker (or Gene Shoemaker) (April 28, 1928 – July 18, 1997) was one of the founders of the fields of planetary science. Born in Los Angeles, California, he is best known for co-discovering the Comet Shoemaker-Levy 9 with his wife Carolyn Shoemaker and David Levy.

Scientific contributions

Meteor Crater

For his Ph.D. at Princeton (1960), Dr. Shoemaker conclusively showed that Barringer Meteor Crater, located near Winslow, Arizona, arose from a meteor impact. From a Geophysical standpoint, it had been proven by 1929 that Meteor Crater was indeed an impact structure. Such personages as Daniel M. Barringer had proven the impact origin by the year 1915 by studying the local terrain, ejecta and the rock floor which is acknowledged in David Krings recent guidebook to Meteor Crater (2007), with Forrest Ray Moulton, an astronomer/mathematician at the University of Chicago had proven in two papers the impact origin as well as predicting where some of the ejecta fragments might be, all by the year 1929. Subsequent work by H. H. Nininger during the 1940-1950 period was aimed at the search for ejecta and other impact byproducts. Shoemaker in the second paragraph of his paper on Impact Mechanics as published in the volume "Moon, Meteorites, and Comets" clearly picked up from where others before him had left off, using their work as a springboard for further studies. He himself lists the references to those earlier papers. Kring in his recent "Guidebook to the Geology of Barringer Meteorite Crater (a.k.a. Meteor Crater)", 2007, clearly points out how the work by Barringer was of a higher quality and more accurate than that of G. K. Gilbert in 1891. Since then Shoemaker has done more than any other person to advance the idea that sudden geologic changes can arise from asteroid strikes and that asteroid strikes are common over geologic time periods. Previously, astroblemes were thought to be remnants of extinct volcanoes -- even on the Moon.

Shoemaker gained this insight after inspecting craters that remained after underground atomic bomb tests at the Nevada Test Site at Yucca Flats. He found a ring of ejected material; in both cases it included shocked quartz (coesite), a form of quartz that has a microscopically unique structure caused by intense pressure.

Astrogeology and Apollo

Dr. Shoemaker helped pioneer the field of astrogeology by founding the Astrogeology Research Program of the USGS in 1961 at Flagstaff, Arizona. He was its first director. He was prominently involved in the Lunar Ranger missions to the Moon, which showed that the Moon was covered with a wide size range of impact craters. Dr. Shoemaker was also involved in the training of the American astronauts. He was set to be the first geologist to walk on the Moon but was disqualified due to being diagnosed with Addison's disease, a disorder of the adrenal gland. Shoemaker would train astronauts during field trips to Meteor Crater and Sunset Crater near Flagstaff.

Coming to Caltech in 1969, he started a systematic search for Earth orbit-crossing asteroids, which resulted in the discovery of several families of such asteroids, including the Apollo asteroids.

Comet Shoemaker-Levy 9

Dr. Shoemaker received the Barringer Medal in 1984 and a National Medal of Science in 1992. In 1993, he co-discovered Comet Shoemaker-Levy 9. This comet was unique in that it provided the first opportunity for scientists to observe the planetary impact of a comet. Shoemaker-Levy 9 collided with Jupiter in 1994. The resulting impact caused a massive "scar" on the face of Jupiter. Most scientists at the time were dubious of whether there would even be any evident markings on the planet.

Death

Dr. Shoemaker spent much of his later years searching for and finding several previously unnoticed or undiscovered meteor craters around the world. It was during one such expedition that Dr. Shoemaker died in a car accident while on the Tanami Road northwest of Alice Springs, Australia in July 1997. On July 31, 1999, some of his ashes were carried to the Moon by the Lunar Prospector space probe in a capsule designed by Carolyn Porco. To date, he is the only person to have been buried on the Moon.

The brass foil wrapping of Dr. Shoemaker's memorial capsule is inscribed with images of Comet Hale-Bopp, the Barringer Crater, and a quotation from Romeo and Juliet reading

"And, when he shall die
Take him and cut him out in little stars
And he will make the face of heaven so fine
That all the world will be in love with night
And pay no worship to the garish sun.

Bibliography

Kring, D.A., (2007) "Guidebook to the Geology of Barringer Meteorite Crater, Arizona (a.k.a. Meteor Crater)". Lunar and Planetary Institute contribution No. 1355