First Light: The Search for the Edge of the Universe (13 page)

“Darn,” his wife said from under the telescope. “I always miss them.”

“That’s because you’re looking through the telescope.”

“It’s not fair, Gene.”

“Aw.”

The little dome was crammed with scientific gear of obscure vintage. There were several stools of different sizes, a lift chair, and two mercury thermometers taped to the wall. There were clocks of all kinds, dead and alive. A sound of clicking relays from the control desk echoed through the dome. A generator hummed under the floor, and the stereo cassette played synthetic violins under the telescope. “Our son Patrick calls this ‘music to go to the dentist by,’ ” Carolyn remarked. The wind drifted through the dome slit, bringing cold through as many layers of clothing as one could possibly wear. The stars were brilliant, intense, too close. Red numbers in a digital clock on the control desk flickered, dissecting time. I sat with my back against the dome and my feet curled up against the base of the telescope, listening to Gene and Carolyn talk quietly with each other. Their hoods were drawn, and they seemed artificially fat in too many clothes. They could have been astronauts. “Everyone seems to be getting divorced these days,” Carolyn said. “I used to think we had a normal marriage. Now I’m not so sure.” I cinched my hood and put on a pair of mittens. The dome slit seemed to be the window of a starship. I dozed off for a while, and when I woke up, there were strange stars in the slit—the sky had moved. We might have been lost in space. “Are you still with us?” Carolyn asked me. I remarked to her that it felt as though we were in free-fall.

“We are,” she said.

She pulled a lever, and the shutters on the telescope’s nose flopped open. “Actually,” she said, “there was a time when I thought I would go into space. I won’t now.” A shower of sparks dropped from the telescope. “A lot of astronomy nowadays is electronic,” she said. “Astronomers watch TV. For me it seems more real to be sitting under the open sky. I like to think that somewhere out there are these little bodies marching by.”

Thoughtfully Gene said, “Those little bodies are generally one to three kilometers across.”

“I think it would be nice to visit one,” Carolyn said.

“It would be easier to reach some earth-crossing asteroids than to reach Mars,” Gene said, standing at the control desk, monitoring the seconds fleeting past.

“What’s my time, Gene?”

“Whoa,” he said.

She reached up and pulled a lever. The telescope’s shutters thudded down. She swung the telescope sideways. She reached into the telescope and unclamped the film holder in order to change the film.

The Main Asteroid Belt, Gene explained, is a collection of close to a million large pieces of rock and iron. Most of them float between the orbits of Mars and Jupiter. But every population has its rogues. When the Main Belt tossed off rogue asteroids, they could go into long, high, slanting orbits; they could approach the earth from any direction. “An earth-crossing asteroid,” Gene said, “can appear essentially anywhere in the sky.”

“How often do asteroids hit the earth?” I asked.

Gene said, without hesitation, “I’ve estimated that you’d get about ten major impacts every million years. Two-thirds of the asteroids land in the sea.”

“What happens during an impact?”

Again without hesitation (he had it all figured out), he said, “If you took all the nuclear weapons in the arsenals of the United States and the Soviet Union—which I think is about twelve thousand megatons of warheads, based on the available public figures—and you put them all in one pile and detonated them, that’s what we’re talking about.”

“I’m ready, Gene,” Carolyn said.

He watched the clock. “Five, four, three, two, one,” and then, lowering his voice, “open.”

In 1932, Karl Reinmuth, an asteroid hunter in Heidelberg, Germany, discovered the first recognized earth-approaching asteroid, a lump of rock one mile across, tumbling past the earth in free-fall. It appeared on a glass photographic plate as a bright line among the stars—a near-earth object traveling quickly. He named it Apollo, after the Greek god who drove the chariot of the sun, because the asteroid’s orbit took it near the sun. Apollo’s orbit
turned out to be unstable, chaotic, and astronomers lost track of it. Apollo popped up again in 1973, when it was rediscovered on another close approach to the earth. Apollo, as it happens, was also the god who fired invisible arrows at mortals to kill them instantaneously.

Five years after he sighted Apollo, Karl Reinmuth discovered another asteroid on a close approach to the earth—Hermes. Hermes boomed past us—missed us by about twice the distance from the earth to the moon, the closest approach by an asteroid that has yet been observed. That sounds like a fairly safe distance, but it is not. There are enough big earth-crossers roaming around to guarantee that once in a while one of them scores a bull’s-eye.

The next discovery of an earth-crosser came in 1949, when a Palomar astronomer named Walter Baade was casually searching a glass plate taken on the forty-eight-inch Schmidt telescope on Palomar Mountain. Baade found a long, bright line tending in an abnormal direction—an asteroid that he named Icarus when he learned that its elongated orbit takes it past Mars, past the earth, past Venus, past Mercury, and close to the sun. Icarus is a cigar-shaped piece of rock a mile long, tinged brown and gray, apparently scorched by the heat from its visits near the sun.

Today less than half a dozen professional astronomers search systematically for wild asteroids traveling in unstable orbits near the earth. Not many astronomers are interested in objects close enough to the earth to actually hit it. We live under sniper fire, which can be witnessed every night—small meteors cutting the atmosphere. Farther out, mountains travel at hypervelocities through the void. A near miss, in astronomical terms, occurs often enough so that a diligent astronomer can earn glory photographing the event. On the Fourth of July, 1973, a former collaborator of Gene’s named Eleanor Helin was working on the eighteen-inch Schmidt telescope on Palomar Mountain when she photographed an enormous, bright asteroid—roughly as big as the peak of Mount Everest—diving through the plane of the solar system and past the earth. During a twenty-minute exposure it made a line in a photograph that looked like a scratch. “It was going like a bat out of hell,” Gene said. Shortly afterward it vanished. It was traveling on a cometary orbit, but unlike any comet, this object had no dusty
tail. It was designated 1973 NA—not a name, a temporary label. 1973 NA will be back, but nobody knows where in the sky or when, because it is now a lost object.

Right after the new year in 1976, Eleanor Helin photographed an object loping alongside the earth, like a car edging up from behind in the fast lane of a freeway. It passed us. Then it moved directly across our lane. She named it Aten. Aten crosses our lane once every twenty years. There are two logical fates for Aten. Either Aten will one day pass so close to the earth that the earth will throw it into a new orbit. “Or,” Gene said, “Aten’s got a damned good chance of hitting the earth.”

Gene and Carolyn Shoemaker have added quite a few earth-crossers to the list. One afternoon in May 1984, Carolyn was in the office at the dome of the Little Eye, searching transparencies of the night sky while Gene brought them fresh from the darkroom. She found a bright, slow-moving object. She telephoned the Minor Planet Center, in Cambridge, Massachusetts, and read the object’s coordinates over the telephone. “The damned thing seemed to be accelerating,” Gene would recall. A short while later a computer at the Minor Planet Center disgorged a solution to the object’s orbit: it appeared to be accelerating because it was heading straight for the earth, like a headlight on an approaching train. This asteroid—1984 KD—zipped past, and it will return again and again, until it either hits the earth or is thrown into a new orbit. As of this writing, 192 earth-crossing asteroids have been discovered, most of them in recent years, and a fair proportion of them by Gene and Carolyn Shoemaker.

An asteroid is a relatively small piece of rock or iron, and the earth is a very large piece of rock and iron, and both are in free-fall around the sun. The wanderings of the earth-crossers take them through the orbit of the earth. Every now and then an unknown earth-crosser appears in the sky—a fast-moving point of light traveling at an average closing speed of fifteen kilometers per second, or thirty-four thousand miles per hour. For more than ten years Gene Shoemaker had been building statistics on earth-crossers, but the problem was that an Apollo object here, an Aten object there, added up to partial statistics. “Maarten Schmidt’s got it easy with his quasars,” he said, “because once you find a quasar,
it doesn’t move.” Where did earth-crossers come from? How many were out there? A “close approach” seemed a rather large distance, except when measured against the huge size of the solar system, where watching a piece of rock close in on the earth at thirty-four thousand miles per hour seemed not unlike being stalled in an automobile on a railroad crossing at night and seeing a light down the tracks. At least you can abandon an automobile. As a statistician and thus a professional giver of odds, Gene Shoemaker saw, with a mathematical clarity, that in the fullness of geologic time what seemed impossible became inevitable: nature’s version of nuclear war.

One night I asked Carolyn, “How did you ever get interested in finding asteroids?”

“It kind of grows on you,” she said. Her voice came out of the darkness under the telescope. “I wanted something to do. I get bored easily. I got tired of being a housewife, I guess. Gene’s really a planetary geologist, not an astronomer. But he does a lot of things. His astronomy was something that really interested me. So I sort of eased into astronomy, part-time at first. In the beginning I didn’t know if I could take staying up all night on the telescope with him. I worried about that. Especially in the winter, when it can get well below freezing in here and the nights last thirteen hours. I can’t wear mittens, because you have to handle a lot of small metal parts when you reach inside the telescope.”

“Close,” Gene said.

She closed the telescope’s shutters and continued. “But when I find a comet or a fast-moving object on a film, there’s a surge of excitement.” She rolled the telescope over on its side, accompanied by a whine of meshing gears. “I get a feeling I’m seeing something that no one else has ever seen before.”

She thought it was time for a cookie break. She turned on the lights and went downstairs, returning in a moment with mugs of coffee and a bag of Oreos. “Would you like one?” she asked, offering me the bag. She had strong hands with rather short fingers.

Several Oreos and a mug of coffee helped to warm me up. I had dredged a pair of ski pants out of my packs, but nothing seemed
to halt the cold. I had decided that the first maxim of survival on Palomar Mountain is that those who eat Oreos live to see the dawn.

“I think I would be a more doting grandmother,” she said, “if I hadn’t gotten so interested in asteroids.” The pleasure of hunting minor planets had soaked up what she called a “restlessness.” Being a mother had fulfilled her, she said, but she did not particularly enjoy being a grandmother. Her restlessness came from something deep, probably the American need to pile everything in a wagon and go looking for Eden. Her father, Leonard Spellmann, had tried silver mining in Colorado, without much success, so he went to New Mexico in 1920 to try homesteading. That might have worked out but for the fact that he met Hazel Arthur, a schoolteacher in Gallup, whom he married. Reluctant to put Hazel on a homestead, he ditched the homestead and moved into Gallup to open a men’s clothing store. That might have been a success but for the fact that the Depression and his business partner cleaned him out. Around that time, Carolyn was born. Leonard picked up and moved the family to Oregon, where he sold insurance. That did not work out. He moved the family to Chico, California, where he sold real estate. There wasn’t much of a market for rural California real estate in the Depression. She said, “Dad was basically a farmer; that was what he knew best.”

“Close,” Gene said.

She closed the shutters, extracted the exposed film holder, replaced it with a fresh one. A chain clinked. She started the next photograph.

In the early 1940s, her father bought a two-acre chicken farm in Chico. He killed and dressed the chickens, while her mother sold the birds to the local people by twos and threes. The family did not have much cash, and at first they found that beans better suited their dinner table than chickens. In the summers Chico became unbearably hot, and when the Spellmann family couldn’t sleep for the heat, they would sit in the yard on blankets at night, and talk, and sing songs. Carolyn Spellmann was a dreamy girl and close to her family. When the singing stopped and the family dropped off to sleep on their blankets, she looked at the huge moon.

Her parents assumed that she and her brother, Richard, would go to college. Richard got into Caltech. The chicken farm could not handle more than one fancy tuition, so Carolyn went to Chico State College, where she could live at home and save on expenses. She eventually got a master’s degree in education. While at Chico State she began hearing from Richard about his roommate at Caltech. Gene Shoemaker, meanwhile, began hearing from his roommate, Richard, about Richard’s sister. By the time Carolyn met the touted Gene, they already liked each other. Then Gene left for graduate school in geology at Princeton University. They wrote letters to each other for a while, until Carolyn suddenly broke off writing.