By Emily Levesque, University of Washington
The husband and wife duo of Gene and Carolyn started off in different fields. But, their interests drew them closer to astronomy. What resulted was a significant contribution by the Shoemakers to the study of the solar system and the discovery of numerous asteroids and comets.
Gene Shoemaker, a Geologist
Gene Shoemaker was born in Los Angeles. His family moved between big cities and rural towns, following his father’s work. As a child in Buffalo, New York, Gene developed a love of science, but he began by looking down rather than up, collecting rocks and minerals.
He was a precocious student, and at age 16 he began college at Caltech. Four years later he had completed a master’s degree in geology and began working for the United States Geological Survey, or USGS.
Fascination with a Crater
At first, Shoemaker’s work had nothing to do with astronomy; he studied uranium deposits and the geology of volcanic vents. His research led him to northern Arizona and, eventually, the immense crater near Flagstaff.
The crater fascinated him so much that he made it the subject of his doctoral thesis at Princeton. Shoemaker recognized that the crater bore a strong resemblance to craters formed during atomic bomb testing.
Planetary Geology
When Shoemaker and his colleagues began studying the chemistry of the crater, they recognized minerals that could only have formed in the high temperatures and pressures of a tremendous impact. They reported that the crater had not been formed by a volcano. It had been formed by a meteor.
Gene Shoemaker’s research marked the beginning of his work in a fledgling field: planetary geology, which later became a crucial branch of planetary science.
Gene Shoemaker’s Contribution to the Apollo Program
Shoemaker went on to work closely with the Apollo program, creating a geologic map of the Moon and helping to train the astronauts who gathered moon rocks and did groundbreaking geological research that helped astronomers better understand the origins of the Moon itself.
Planetary science has experienced an immense evolution in the years since the Apollo program. We haven’t yet sent crewed missions to any other objects in the solar system, but we have capitalized on humanity’s spaceflight abilities to send missions all over the solar system, including many that have specifically focused on studying asteroids and comets.
Shoemaker himself had dreamed of being the first scientist to visit the Moon. Unfortunately, he was diagnosed with Addison’s disease in 1963, an illness that disqualified him from the astronaut corps.
However, he continued to campaign vigorously for the inclusion of a geologist among NASA’s lunar astronauts and succeeded when fellow Caltech-trained geologist Harrison “Jack” Schmitt visited and explored the Moon as a crew member of Apollo 17.
Identifying Asteroids and Comets
In the years after Project Apollo, Gene Shoemaker turned his attention to searching for asteroids and comets that might impact the Earth. His work involved identifying these small faint members of our solar system and then mapping their orbits.
With enough observations, he and his colleagues could project the paths of asteroids and comets and keep a particular eye out for ones that could cross Earth’s path.
This article comes directly from content in the video series Great Heroes and Discoveries of Astronomy. Watch it now, on Wondrium.
Carolyn Shoemaker’s Discovery of Asteroids and Comets
One of Gene’s colleagues in this work was his wife, Carolyn Shoemaker. Carolyn was not a scientist by training; she’d studied political science and English literature and spent the first part of her life as a stay-at-home mother, raising her and Gene’s three children.
In 1980, with her children out of the house, Carolyn began a second profession as an astronomer at the age of 51. She worked as Gene’s field assistant studying impact craters and searching for Earth-crossing objects; she personally discovered more than 800 asteroids and 32 comets.
Discovery of the Comet Shoemaker-Levy 9
In March of 1993, the Shoemakers, working together with amateur astronomer David Levy, discovered an unusual comet. It had once been traveling happily through the solar system, but a close pass near Jupiter had torn the comet into fragments and dragged it into an orbit around the giant planet.
Using the same technique that they applied to search for near-Earth asteroids, the Shoemakers and Levy projected the comet’s path forward and eventually realized that the comet was on a collision course—not with Earth, but with Jupiter.
The comet, dubbed Shoemaker-Levy 9, slammed into Jupiter in July of 1994. Prior to the impact, astronomers hadn’t been certain of what they would see, but observations from the Hubble Space Telescope quickly revealed the dramatic evidence of the collision.
Shoemaker-Levy 9 left a string of dark bruises along Jupiter’s southern flank that were visible for months afterward. It was the most dramatic collision ever observed by modern astronomers.
Shoemaker’s Final Days
Tragically, Gene Shoemaker passed away just a few years later in a car crash while on an impact crater expedition in Australia. Carolyn, who was injured in the crash, later resumed her planetary science work.
She continued to emphasize the importance of understanding the composition and physics of asteroids and comets, both for learning more about our solar system, and for understanding the fate of our own planet.
Common Questions about the Shoemakers, and Their Contribution to Astronomy
When Gene Shoemaker and his colleagues began studying the chemistry of the crater, they recognized minerals that could only have formed in the high temperatures and pressures of a tremendous impact. They reported that the crater had not been formed by a volcano. It had been formed by a meteor.
Carolyn Shoemaker worked as Gene’s field assistant studying impact craters and searching for Earth-crossing objects; she personally discovered more than 800 asteroids and 32 comets. She continued to emphasize the importance of understanding the composition and physics of asteroids and comets, both for learning more about our solar system, and for understanding the fate of our own planet.
In March of 1993, the Shoemakers, working together with amateur astronomer David Levy, discovered an unusual comet. They projected the comet’s path forward and eventually realized that the comet was on a collision course—not with Earth, but with Jupiter. The comet, dubbed Shoemaker-Levy 9, slammed into Jupiter in July of 1994. Shoemaker-Levy 9 left a string of dark bruises along Jupiter’s southern flank that were visible for months afterward. It was the most dramatic collision ever observed by modern astronomers.
