She's Looking Out for Us

Shoemaker: Comet Finder

Carolyn Shoemaker built a successful career as a mother, wife and homemaker. Then, when her children were grown, she decided to start a new career after age 50.

And she became one of the leading scientists in her field.

Today, Shoemaker is an internationally known astronomer, the discoverer of 32 comets and more than 800 asteroids.

She is on the staff of Lowell Observatory in Flagstaff, Ariz., and a volunteer in astrogeologic studies with the U.S. Geological Survey.

She may be best known as co-discoverer of the Shoemaker-Levy 9 comet, which struck Jupiter in July 1994, but her work ranges from meteorite studies to investigation of ancient impact structures.

Shoemaker will present the inaugural Michel T. Halbouty Lecture on June 4 at the 2001 AAPG annual meeting in Denver. In her presentation, "Through a Crystal Ball," she'll examine a subject of potentially Earth-shattering importance.

"There was a time (when) people here on Earth thought the planets were surrounded by crystal balls and nothing could penetrate that," she said.

"It doesn't take a crystal ball to tell us we're going to be hit by a comet or an asteroid of varying (possible) size."

That's a likelihood -- but not a prediction of catastrophe, she quickly added.

"A lot of people say 'Impact! We're going to be destroyed!' -- á la the impact at the Cretaceous boundary," she said. "But those don't happen very often."

When astronomers detect and track objects in space today, they can predict the odds of an Earth collision using powerful computer models. The occasional report of impending doom should be dismissed as heaven-high hype, according to Shoemaker.

Image Caption

The last image of asteroid 433 Eros received from NEAR Shoemaker was taken from a range of 394 feet and measures 20 feet across. The streaky lines at the bottom indicate loss of signal as the spacecraft touched down on the asteroid during transmission of the image.

Please log in to read the full article

Carolyn Shoemaker built a successful career as a mother, wife and homemaker. Then, when her children were grown, she decided to start a new career after age 50.

And she became one of the leading scientists in her field.

Today, Shoemaker is an internationally known astronomer, the discoverer of 32 comets and more than 800 asteroids.

She is on the staff of Lowell Observatory in Flagstaff, Ariz., and a volunteer in astrogeologic studies with the U.S. Geological Survey.

She may be best known as co-discoverer of the Shoemaker-Levy 9 comet, which struck Jupiter in July 1994, but her work ranges from meteorite studies to investigation of ancient impact structures.

Shoemaker will present the inaugural Michel T. Halbouty Lecture on June 4 at the 2001 AAPG annual meeting in Denver. In her presentation, "Through a Crystal Ball," she'll examine a subject of potentially Earth-shattering importance.

"There was a time (when) people here on Earth thought the planets were surrounded by crystal balls and nothing could penetrate that," she said.

"It doesn't take a crystal ball to tell us we're going to be hit by a comet or an asteroid of varying (possible) size."

That's a likelihood -- but not a prediction of catastrophe, she quickly added.

"A lot of people say 'Impact! We're going to be destroyed!' -- á la the impact at the Cretaceous boundary," she said. "But those don't happen very often."

When astronomers detect and track objects in space today, they can predict the odds of an Earth collision using powerful computer models. The occasional report of impending doom should be dismissed as heaven-high hype, according to Shoemaker.

"Thanks to some sophisticated computer technology, we can say, 'Yes, it's possible that this certain object of a certain size will impact the Earth at some time,'" she noted.

"The trouble is, everyone who spots one of these things reports it to the Minor Planet Center in Cambridge, Mass. They put these on the Web, and when the media get a hold of something without time for confirmation, they run away with it."

Lead times for predicting a possible Earth strike should provide plenty of opportunity to do more than duck. She said the length of time between a first warning and an actual impact would be "desirably, 50 years, but 20 years isn't bad."

Astronomers work in a timeframe of 100 years or more in tracing near-Earth orbit (NEO) objects, she noted. According to NASA, the chance of any presently known NEO hitting Earth in the next 100 years is negligible.

Chapter Two

Shoemaker was married to famed geologist and AAPG member Eugene Shoemaker, who founded the USGS astrogeology center in Flagstaff. Her husband died in an automobile accident in July 1997. Shoemaker herself was injured in the crash, which occurred during the couple's annual trip to study impact craters in Australia.

Over a 13-year period, the two had studied more than 20 impact structures there, mapping them, doing magnetic and gravimetric surveys, searching for impact glass and meteorites -- doing whatever had not already been done by the Australians.

By the end of that period, other impact structures, some subsurface, were being found in the course of drilling for oil. Among those were the Tookoonooka and Tidibilly craters.

Her career in astronomy began in 1980, after she asked her husband to suggest a pastime.

"It was not until our children left, the three of them, that I turned to my husband, Gene, and said, 'Do you have anything that would interest me the same way geology interests you?' That's like, 48 hours a day," she recalled.

As it happened, he was looking for help in a search for objects in space that might intercept Earth's orbit, "especially things that could have a chance to hit Earth."

Shoemaker majored in history and political science at Chico State College in California, where she was a cum laude graduate in 1949 and received a master's degree in 1950.

Faced with the possibility of entering a completely different field 30 years later... she jumped at it.

And she jumped into her new career, as well. She became a research assistant at the California Institute of Technology and then a research professor of astronomy at Northern Arizona University, where she earned a doctorate in science in 1990.

With Eugene Shoemaker, she has been honored with numerous medals and awards for science and research during the past 14 years. In 1996, she became a Fellow of the American Academy of Arts and Sciences and received NASA's Exceptional Scientific Achievement Medal.

She has found or co-discovered more comets than any other living astronomer. Of the more than 800 asteroids she has discovered, more than 300 are officially designated with numbers.

Shoemaker also developed new stereoscopic techniques for scanning films at the Palomar Observatory in California. Those techniques more than doubled the potential rate of sky coverage of the observatory's 46cm Schmidt camera.

Craters -- and Oil Potential

Despite recent knee-replacement surgery, her work goes on at a fast pace. She continues to hunt for comets with associate David Levy, the Canadian-born astronomer, journalist and lecturer, who also lives in Arizona.

"It's still the old-fashioned technique of photography," she said, "but we can look close to the sun to avoid the other sky surveys."

In addition to staking out their own expanse of sky, the near-sun approach gives them a decided advantage in comet gazing: That's where comets glow most brightly, Shoemaker noted.

Another continuing project is finishing her husband's papers and research reports. That involves working through "a big backlog of Australian crater work," gathered by them during their 13 years of field trips, she said.

She thinks the cratering work will interest petroleum geologists, since impact craters indicate a possible oil reservoir. About 25 percent of the Earth's impact craters are associated with economic resources of some kind.

"Quite a number of the craters have been discovered in Australia and also in the United States that are subsurface and are oil bearing," she said. "When there is an impact, the area beneath the impact is full of brecciated, broken-up rock, and it's a good, good reservoir."

Most impact craters share similarities, according to Shoemaker. Large structures typically have a central uplift or peak, and may show several ring depressions, what she called a "rock into mudpuddle" spreading pattern.

Yet the craters are different enough to reward individual examination.

"Each structure we've studied has something new to offer," she said.

Catch a Falling Star?

Advances in space exploration are bringing new mysteries for Shoemaker to ponder. During the past year, she observed the results of NASA's Near Earth Asteroid Rendezvous mission.

NASA named the mission's space probe NEAR Shoemaker in honor of Eugene Shoemaker, who had long spoken of the importance of a mission to an asteroid.

For one year, the probe orbited the asteroid Eros, 196 million miles from Earth, sending back about 160,000 images.

At the end of the mission, NASA officials decided to try a chancy maneuver -- setting down NEAR Shoemaker on the surface of the 21-mile-long asteroid.

"I actually went back to the Advanced Physics Lab to see it go down," Shoemaker said. "I can tell you that the feeling of elation was just enormous."

While the controlled crash-landing of the NEAR Shoemaker craft made headlines, asteroid specialists puzzled over the information provided by the probe's abundant images. Shoemaker found that the data led to more questions than answers.

"One of the things that amazed us is that Eros had so many boulders of all sizes on the surface," she said. "Eros doesn't have much gravity, so what are all the boulders doing there?"

By her own description, Shoemaker also continues to work with the USGS as an "emeritus volunteer," mainly in impact crater studies. She feels she has no time to waste in her delayed second career.

"I don't have time to retire," she said. "I have too much to do, and not enough time."

vvcfazbfuscfvbycvqytsxyazsbeucffrv

You may also be interested in ...