Gene Shoemaker was an astronomer and geologist who was fortunate enough to be born at the perfect time, just as watchful eyes were turning toward the Moon. He was also resourceful enough to make this time his own. Born 28 April 1928, Gene was firmly hooked on geology not long after his mother gave him, at age 7, a set of agate marbles. Educated in Los Angeles, he received a BSc from Caltech in 1947 and a masters degree from the same institution in 1948.
Out in Colorado plateaus in 1948, Gene Shoemaker was sure that humans would land on the Moon in his lifetime. "It all came to me in a flash one morning while driving to breakfast," he recalled. Only 20 years old, he was living in a mill camp in West Vancoram, Colorado, preparing for a diamond drilling project. Already he had made up his mind that the Earth would be his laboratory, but on that morning the Earth suddenly was no longer enough.
"I had my meals five miles away in Maturita, down at the headquarters of the Vanadium Corporation of America," he reminisced. "I was driving along the road along this beautiful river. Aha! That is what I will aim to do: to be one of the first people on the Moon. Why will we go to the Moon? To explore it, of course! And who is the best person to do that? A geologist, of course! I took the first fork that went to the Moon that morning."
If that daybreak drive saw the start of Shoemaker's road to the Moon, joining the US Geological Survey that summer was his first turn. By the end of the 1950's, Gene had confirmed the extraterrestrial nature of the feature on Coon Butte, Arizona, called Meteor Crater, a project that led to his PhD from Princeton. The key was the discovery of coesite, a mineral that could be formed under the intense conditions of heat and pressure available at the moment of an impact. By 1960, coesite was found in specimens from around Meteor Crater.
At the same time, Gene began a project to do the first geological map of an extraterrestrial body, the Moon. He proceeded by using photographs. Some 40 years earlier, on exceptionally steady nights when the 100-inch Hooker telescope at Mt. Wilson Observatory had been new, Francis Pease had taken such high quality photographs of the Moon that they picked up craters as small as one kilometer in diameter. Shoemaker had enlargements made of the region around the crater Copernicus, a huge feature that might have resulted from a comet impact about a billion years ago. From these photographs, his team made the first geologic map of a lunar feature. Besides Copernicus, the map showed a whole set of geological features in a region about the size of Arizona. Later he expanded the project until it eventually included 50 quadrangles covering much of the side of the Moon visible from Earth.
In 1960, Shoemaker joined the television team for Project Ranger, which sent a small spacecraft to the Moon. The next year, the USGS set up a formal Branch of Astrogeology, with Shoemaker as branch chief. During the 1960' s, Gene was as close to the Moon as he would ever get—working with the Ranger and Surveyor projects, choosing the one geologist, Harrison Schmidt, who would eventually go to the Moon, and providing geologic training to the Apollo astronauts. For some years, Gene hoped to go to the Moon himself, but Addison's disease, diagnosed in 1963, cost him that dream. In 1994, through the eyes of the Clementine spacecraft, he surreptitiously visited the Moon once more.
Shoemaker was the principal investigator for the field geology experiments for the first three Apollo Moon landings. His team set up a mock lunar landing site, complete with small artificial craters and a full-sized model of the lunar module, to give the astronauts a chance to practice geological field techniques. "Some of those test pilots were very good observers," Shoemaker remembered, adding how their flight training and alertness gave them the potential to be ideal field geologists.
For Shoemaker, Apollo 11's return to Earth was the beginning of one of his biggest disappointments. "NASA wanted to plot out every minute of every field traverse in advance," he huffed. "That plan mitigated against discovery." Thinking as a field geologist, Shoemaker believed that the Apollo program, successful as it was, was a lost opportunity. "Discovery begins when you see something you don't expect," he explained. "Then you go look. Apollo never provided that opportunity. It provided outstanding science, " Shoemaker said, "but the discoveries came from the analysis of the samples brought back, not from the observations of the astronauts. And that was the issue. Why send humans into space if not to be prepared for the unexpected?"
"My dream for Apollo," Shoemaker explained, "was to try to create the opportunity to show what a well-trained human being could do on the spot. This is not a kind of science that most scientists understand, because they don't do it. And in the six moon landings, we never demonstrated that important discoveries could be made from field observations."
After Apollo, Gene's work took a very different direction. With his wife Carolyn, he conducted a photographic patrol of the night sky for comets and asteroids, objects he believed pose a threat to the Earth. Conducted with Palomar Observatory's 18-inch Schmidt camera, the program was a spectacular success. On more than 20,000 films, 32 comets and hundreds of asteroids were discovered before the program ended in 1994. The most famous discovery appeared on two films taken by the Shoemakers and David Levy on 23 March 1993. A comet appeared on those films, a comet which had been catastrophically disrupted by Jupiter and which was orbiting away from Jupiter in several pieces. On 22 May 1993, the International Astronomical Union announced that Comet Shoemaker-Levy 9 would continue receding from Jupiter until July, when it would begin to swing around and head back. On 16 July 1994, the first of Shoemaker-Levy 9's 21 fragments collided with Jupiter. The show that followed was a spectacular confirmation of Gene Shoemaker's cherished belief that cosmic impacts played a major force in the shaping of the planets. For Gene and Carolyn, the third week of July 1994 was sweet indeed.
The Shoemakers used their summers to investigate impact sites in the Australian outback. They looked forward to this unparalleled opportunity to study, in one of the Earth's most remote regions, the geological forces of impact that shaped our planet. These were precious times for Gene and Carolyn, times to get away from email and business, and closer to the planet they loved. On Friday, 18 July 1997, a few hundred kilometers north of Alice Springs, their automobile collided head on with another vehicle. No one was seriously injured in the other car, but Gene died instantly, and Carolyn sustained serious injuries. Gene died in the place he loved, but his time came far too soon. His legacy was nothing short of a whole new look at the worlds in our solar system, and of the impact forces that shaped these worlds.
Other obituaries and appreciations of Eugene Shoemaker have appeared in Sky and Telescope (November 1997), Science (277, 776), Nature (389, 132), and The Economist (2 August, p. 70). His papers are currently housed at the US Geological Survey in Flagstaff.
Photo (available in the PDF version) courtesy US Geologic Survey.