First Light: The Search for the Edge of the Universe (12 page)

Among women, only Caroline Herschel, an Englishwoman who lived in the days of Jane Austen, had found more comets than Carolyn Shoemaker—eight—searching with a modest telescope that her brother, Sir William Herschel, had built for her. “I intend to beat Caroline,” Carolyn remarked coolly. After that she was going to beat Mr. Honda, Mr. Bradfield, and Dr. Mrkos, three astronomers who were then tied for first place among living comet discoverers, with twelve comets each.

Each observing run on Palomar Mountain yielded a pile of photographic negatives, which Carolyn scanned in Flagstaff using her stereomicroscope. But the microscope went virtually everywhere Carolyn did. She brought it to the mountain in order to search films when Gene brought them fresh from the darkroom, since an earth-approaching asteroid could whip past the earth in a few days. When she searched for comets and asteroids, she inserted pairs of negatives into the microscope—photographs of star fields taken at intervals of forty minutes. An object in motion in the solar system would move enough during forty minutes to appear to jump out before her eyes, in stereo. Each pair of photographs contained around ten thousand stars or starlike objects. Most of them really were stars, yet the photographs were sprinkled with moving debris. Normal asteroids streamed in the same direction, like schooling fish. Abnormal ones, dangerous objects, things that could hit the
earth, often went backward, against the normal flow of debris, or they slashed diagonally across the field of view, or they popped out, moving too fast. Carolyn had very sharp eyes, and she was always on the lookout for things that moved.

“Gene!” she said. “Is that car following us John Law?”

The Fury rocked as Gene turned around to look. “I hope not,” he said.

“In Arizona,” Carolyn remarked, “you can be jailed for speeding.” The police had explained this to the Shoemakers before. She did not want a search for minor planets to end in jail.

The rain stopped and the clouds broke. A whitish pink star gleamed in the west, dead ahead. “Ah, Jupiter,” Carolyn said. “A good sign.” We switchbacked off the edge of the Colorado Plateau and down into the Mojave Desert. Carolyn propped a cassette player on the front seat and played a tape of Herb Alpert and the Tijuana Brass. The Milky Way arched overhead, and Jupiter dropped westward into basin and range. Jupiter is a big planet—the earth would fit easily inside Jupiter’s Great Red Spot. Apart from the sun, Jupiter is the most influential piece of mass in the solar system. It seemed that Jupiter’s gravity was warping Gene’s foot to the gas pedal, pulling the Fury westward. In more than a metaphorical sense, Gene Shoemaker lived with his foot loaded on the accelerator. “I get cranked up over much more than I can finish,” he said. “But I’ve resolved to spend my life, whatever time I have, in doing what’s fun—”

“Nowadays you have to weed out what’s really fun from what’s just fun,” his wife said.

“Yeah, I’ve got a bunch of irons in the fire, all interconnected—”

“If you could only stay off the committees—”

“Ha!” he said, meaning, “Fat chance.”

Gene’s scientific work in various fields had earned him some eleven medals and awards, which had piled up whimsically in boxes on top of the piano at home. He had served as a Principal Investigator with various NASA missions to the moon, and now he served as a member of the Voyager imaging team. If the field of impact geology—the study of what happens when a piece of rock or ice hits a planet—could be said to have a founder, it would
be Gene Shoemaker. Caltech astronomers, weaned on the Hale Telescope, are quintessentially what are known as extragalactic types. To many of them the solar system is the deadest game in the house, offering little scientific challenge—nine balls of nonluminous matter whirling around a (pathetically) normal star, in addition to some gritty stuff, such as asteroids, moons, and comets: the two-dollar table in the grand casino of the sky. The following comments, which I heard in various places around Caltech at various times, give some idea of the attitude of many astronomers toward the solar system.

“If it’s inside our galaxy, it isn’t worth looking at.”

“I simply cannot imagine looking for asteroids as a way to make a living.”

“Planets are the slag heaps of the universe. The earth is a prime example of that. The only thing the earth is good for is to serve as a platform for a telescope. But we are going to have to get rid of this atmosphere. Then maybe we will see something interesting.”

“I could care less if I found a comet. Unless it was going to hit the earth. Then I wouldn’t want my name on it, anyway.”

Gene Shoemaker offered an oblique reply to defamation of planets. “The solar system
is
an insignificant bunch of dust,” he admitted. “It also happens to be where we live.” Somewhere in his mind’s eye, or maybe in his heart, Gene carried a peculiar vision of the solar system. It was not any solar system that I had ever heard of before. In schoolbooks the solar system is pictured as a series of flat, concentric circles centered on the sun, each circle representing the orbit of a planet. In Gene’s mind the solar system was a spheroid. In Gene’s mind the solar system was not at all the eternal, unvarying mechanism envisioned by Isaac Newton, but a carnival—a dynamic, evolving cloud of debris, filigreed with bands and shells of shrapnel, full of bits and pieces of material liable to be pumped into ellipses and loops and long, chaotic, wobbling orbits which carried drifting projectiles all over the place—minor planets that, every once in a while, would take a hook into a major planet, causing a major explosion. He said, “There’s just a zoo of beasts out there, roaming the solar system. While it’s tremendous fun discovering these little planets, the real fun is trying to find out what the heck they are and how they fit into the origin of the solar
system.” Curiosity, he had decided, was one of the two major forces that drove scientists, the other being a characteristically human wish to make a discovery for which one would be remembered after one was gone. “The trick,” he said, “is to keep the bad ideas to a minimum.” He grinned lopsidedly. “Which is not always possible.” Then he swung the Fury into the breakdown lane and brought it to a halt. Time to switch drivers.

We piled out of the car onto a ribbon of highway that crossed a desert playa between mountain ranges. Not a pair of headlights was in view. Gene stood in the middle of the road and stretched. He leaned back and looked up. He said, “The Trojans would be dead overhead.” His belt buckle glinted in the starlight—it was made of silver, in the shape of a many-rayed star. The sky glittered with lights, but the cloud of Trojan planets was invisible, twenty thousand times fainter than any star the naked eye could see. “Science,” he suddenly remarked, “is not at all what you think it is.”

I said, “It sounds like you and Carolyn plan to discover a new asteroid belt.”

“Van Houten discovered it, in a sense—when he came up with that estimate of nine hundred Trojans. I just think it’s a heck of a lot bigger than anyone else does.”

A smell of damp creosote bushes filled the air. It had been raining in the desert. Not a good sign. “Heaven knows what it’s doing on the mountain,” Carolyn said. We climbed into the Fury, slammed the doors, and she floored the accelerator.

Gene began to talk about comets. One of the more intriguing shells of debris, to him, was the solar system’s reservoir of comets. Beyond the outermost known planet, Pluto, there is a spherical shell of comets known as the Oort cloud, named after the Dutch astronomer Jan Oort, who demonstrated its existence. The Oort cloud contains a prodigious number of comets—anywhere from one trillion to one quadrillion comets (nobody can say how many) traveling in circular orbits around the sun, orbits that may average about a light-year from the sun. (If Pluto’s orbit were the size of a dime, then a typical Oort comet would circle about ten yards out.) Comets are lumps of crumbly material, five or ten miles across, containing various kinds of ices, silica dust, and carbonaceous
compounds. Comets are primordial pieces of the solar system, trash left over after the planets formed.

From out in the Oort cloud the sun would look like a bright star. Out there a typical comet travels slowly in relation to the sun—about three hundred miles per hour. Out there a comet can feel the gravity of stars other than the sun. The sun, Gene pointed out, was circling around the galaxy in the company of stars all around it (his vision of the galaxy ran parallel to his vision of the solar system: the galaxy was a collection of moving objects). All the stars in the sky were in motion around the galactic center, like traffic on a freeway. If a comet feels a gravitational pull from a passing star, the comet can, in some cases, be slowed down nearly to a halt—to a speed of around five or ten miles per hour in relation to the sun. Then it does what any object would do if suspended motionless over the sun. It falls toward the sun. By the time it reaches the inner solar system, the comet is falling at outrageous velocity. It takes a hairpin turn around the sun and heads back for the Oort cloud. Some comets actually hit the sun. Pondering comets dropping through the solar system, Gene Shoemaker wondered how often comets got trapped in the zone of planets. A comet could loop past Jupiter, for example; be slowed down by Jupiter’s gravity; and wind up in an orbit near the sun. The zone of planets might be filled with invisible comets. The comets were invisible because they no longer sported tails. A comet began to steam as it neared the sun and the ices in it evaporated. The comet threw off dust as well. The result was the well-known display of a tail. If a comet was trapped in an orbit near the sun, then over time the ice in the comet nucleus might steam away.

One school of thought held that the ice in comets finally evaporated, leaving nothing but a whiff of dust behind. Gene disagreed. He suspected that a black nugget might remain—an extinct comet nucleus, maybe a mile across. “As the comet degasses, it grows a crust of dirt on it,” he said, “like melting snow. You get the buildup of a lag deposit on the surface of the nucleus, probably some kind of polymerized hydrocarbon and rocky stuff, sort of like asphalt.” The surface of an aging comet nucleus began to resemble a melting snowbank in the Bronx. The center stayed frozen, while the outer surface of the nucleus grew a skin of crud. As the crud thickened,
the nucleus stopped throwing off dust. The tail vanished. Seen through a telescope, the comet now looked like a black asteroid. By definition it was now a minor planet on a chaotic orbit, a loose cannonball, rolling at large through the solar system.

A dead comet might wash up in a number of places. Its most probable fate would be to pass close to Jupiter and be whiplashed out of the solar system. Or perhaps it might get trapped inside the asteroid belt, to mix with the asteroids. Or it might hit Jupiter. Or—just possibly—it might end up colliding with the earth.

At three o’clock in the morning Carolyn swung the Fury into a truck stop in the Mojave Desert. We sat at a counter while a waitress in a checked pantsuit poured out three cups of coffee.

Had there been more comets at times in the past? Gene wondered out loud. Had there been comet showers? he wondered. What could cause a comet shower? He pondered these questions while he swigged coffee.

The waitress stood by the cash register with her arms folded, watching Gene. The coffee shop was otherwise empty.

Carolyn remarked, “Gene’s wheels are always spinning.”

“Yeah,” he said, “and every now and then something kicks out.” What would happen, he asked, if a star as big as the sun brushed near enough to the solar system to drill through the Oort comet cloud? He said, “I’ve calculated that we might have a close encounter with a big star maybe once every hundred million years. If a star the size of the sun went by slowly, it could give the Oort cloud one hell of a kick. That star could bore a hole through the Oort cloud. Comets would diffuse out of the cloud in all directions, which would increase the bombardment rate of the earth. We might be in the tail end of a comet shower right now.”

The waitress came over. “Need ‘nother coffee?”

“Sure,” he said. “A comet coming in from the Oort cloud could do some damage if it hit.”

The waitress filled our cups. She peered at Gene.

“These guys,” he said, “travel at sixty-five kilometers per second, relative to the earth—that’s triple the speed of the average near-earth asteroid.” During a comet shower the earth might experience a series of bad random hits, like a chain of nuclear attacks. One result, in the past, might have been the wave of animal and plant
extinctions at the end of the Cretaceous period, sixty-five million years ago, when something like half of the species on earth vanished, including the dinosaurs.

Gene went to the rest room, and the waitress chose that moment to come over with the check. She said quietly to Carolyn, “Have you all seen the Space Center up north of here?”

“You mean Edwards Air Force Base?” Carolyn asked.

“No. You know—where the starships landed.”

“Oh?” Carolyn said.

“Where the aliens left those rock piles. You must’ve heard about that—since your husband is interested in that kind of thing. Those messages to outer space.”

“That sounds interesting,” said Carolyn.

“There’s forces that keep the rocks together. Kids on motorbikes will knock the rocks away, you know? And the rocks will move back during the night. Nobody knows how it happens.”

Carolyn paid the check.

The waitress added, “It might be some kind of magnetic force.”

“We should go and have a look,” Carolyn said.

“Don’t miss it. Spacemen landed there. Have a nice night.”

T
he Pacific Ocean sent a series of cloud fronts over Palomar Mountain, leaving the astronomers there feeling swindled. We stayed in a cottage on the hillside below the dome of the eighteen-inch telescope, staring out the windows over long breakfasts in the early afternoon. After breakfast we would hike or drive up to the dome, where Gene and Carolyn would tackle such work as they could find, while waiting for the weather to clear. The dome of the Little Eye, as astronomers sometimes called the eighteen-inch Schmidt telescope, was shaped like a bullet. The dome was eighteen feet across, offering more than a slight resemblance to a space capsule. It had two floors. On the lower floor were a tiny office, a darkroom, a supply closet, and a bathroom. On the upper floor stood the telescope. The entire dome would have almost fit inside the barrel of the Hale Telescope.

Gene worked in the darkroom. He mixed up tanks of darkroom chemicals. He unraveled a spool of Kodak IIa-D astronomical film, as big as a roll of paper towels, and chopped the film into six-inch disks, using a machine he called the Cookie Cutter. A boisterous racket came out of the darkroom.
Whomp
. Then a muffled “Damn.”
Whomp
. The Shoemakers called these disks of film cookies. Gene filled three ammunition boxes with cookies. Ammo for the telescope. He carried the ammo boxes up to a laboratory at the Big Eye, where he injected them with nitrogen gas and baked them in an oven, to hypersensitize the films to faint light. “It’s a black art,” he said.

Carolyn set up her microscope in the dome’s office and passed the time searching old films for asteroids. She always had a backlog
of films. Her children marveled at her growing passion for minor planets, although perhaps they missed her a bit, because she spent so much time on Palomar Mountain. She listened to the radio while she worked, to a station that claimed it brought you absolutely the easiest listening in southern California. Every now and then she pulled apart the slats of a venetian blind to examine cloud streets and mares’ tails sliding over the mountain. Life on Palomar goes catatonic under clouds. Down at the Monastery, astronomers sat around watching television, hoping for news of a break in the weather.

At the Little Eye, Gene spread out a sheaf of papers and wrote numbers in columns, planning the star fields they would photograph during that run; a geologist plotting a raid on heaven. This weather was beginning to get to him. He began to wonder if the Trojan planets would escape. He paced the office, looking over Carolyn’s shoulder. One afternoon he suddenly vanished into the supply closet. Then his voice boomed: “Where did all these ants come from?” Tiny black ants plagued the eighteen-inch dome, and they had infested the supply closet. “Something really ought to be done about these ants,” he said. But he had no idea what. He emerged with a jar of peanut butter and a spoon. He said to Carolyn, “Is this our peanut butter or has it been here awhile?”

“It’s been here awhile.”

“Want some?”

“No thanks, she said.”

He pulled his half-glasses down his nose and inspected the peanut butter for ants. “Hm.” He spooned a gob into his mouth. He swallowed it tentatively. Not immediately toxic, anyway.

“I’ve got something here that looks like a comet,” she said.

“Oh, yeah?”

“A little fuzzy comet.” She studied a loose-leaf binder containing recent notices of comets.

He sat down at the microscope. He couldn’t find the comet. “Sometimes,” he said, “I think I’m losing my—”

“Marbles?” she said, teasing him.

“Oh, yeah. It doesn’t have a well-defined nucleus.” They concluded it was only a galaxy.

Gene thought that he would call Bob Thicksten, the observatory
superintendent. “Hi, Bob. Just wanted to see what our status is on the clocks.… Still slipping some? Uh-huh …”

“Rats,” Carolyn said.

“We’ll follow it carefully. What’s the weather going to do? Grim? Ha, ha, well, the sky looks better than it has all day.”

Gene’s hopes for better weather proved to be unsupported by reason. A loud noise rattled on the metal dome. “What is that?” he cried, opening the door. A flash of lightning spilled into the office, followed by a rumble. “Aw, for crying out loud,” he said. The ground was covered with hail.

This kind of thing went on for three days.

One afternoon Don Schneider showed up at the Monastery for breakfast. He poured some Rice Krispies into a bowl, juggled a hot Danish pastry out of the microwave, and said, “It’s going to clear.”

That jerked a few heads at the table.

“Have you heard a weather report, Don?”

“No, but Maarten Schmidt is arriving tonight.”

“Oh, yeah. Maarten is supposed to have luck with weather.”

“It isn’t luck.”

“What—does Maarten have a hot line to God?”

“No,” Don said. “God has a hot line to Maarten Schmidt.”

That evening, something in the gestures of the clouds tempted the Shoemakers to walk to the Hale dome, to get up on the catwalk for a view. They followed a road along the ridge, past scrub oaks and chokecherry bushes. Small flocks of birds flew in the wind. The air smelled of dead leaves and carried an edge of cold. A flicker of white and blue burst out of the underbrush, and a blue jay took off with a chokecherry in its beak. The Shoemakers circled the catwalk of the Hale dome, eyeing the clouds.

“Heaven knows what it will do,” Carolyn said.

“A clear night’s not impossible,” Gene said hopefully.

As they so often did, they spent a moment admiring the Hale Telescope from a walkway inside the dome. “Anybody who isn’t awed by that thing doesn’t have a soul,” Gene remarked. The Hale had something in common with the Hoover Dam, perhaps the naïveté of a world that still believed in its machines. The Hale Telescope embodied some of the longings of the twentieth century,
and some of the terror. Gunn and Schneider were working in the cage at the base of the telescope, preparing for a quasar search. Something glittered in Gunn’s hands: the pyramid of mirrored quartz that broke starlight into four beams.

The Shoemakers cooked some quick hamburgers in the cottage where we were staying, in case the weather cleared. We ate them quickly, watching the clouds through the window. At dusk, while we were sitting around drinking coffee, we noticed a tall figure walk by on the road, his hands in the pockets of his parka and his head down, lost in thought. Maarten Schmidt had arrived. Ten minutes later the clouds broke and vanished.

Gene and Carolyn stuffed the coffeepot into a paper bag, along with a pack of Oreos, and carried the bag out to the Fury. They drove up to the little dome and parked. While Gene worked in the office, Carolyn climbed to the upper floor of the dome and pulled a plastic sheet off the telescope (the dome leaked). She hit a button. With a screech bad enough to spall one’s teeth, two curved doors on the dome pulled open. Hitting another button, she rotated the dome to the north, toward Cygnus, the Swan, a constellation that straddles the Milky Way. Twilight had eased off, and the black rift in Cygnus—a lane of dust in the Milky Way—was beginning to stand out. Hauling on a circle of hand holes at the telescope’s base, she pointed it at the brightest star in Cygnus—Deneb—and looked at it through a guide telescope mounted on the barrel of the Schmidt. She fiddled with the Schmidt for a while, calibrating it. Not much bigger than a refrigerator, the telescope was coated with Dutch Boy battleship-gray paint. Rivets and dents on its tube suggested the hull of a submarine that had had some close calls with depth charges. Styled and built during the Depression, the Little Eye looked a bit like an aerodynamic pear, a design that its builders had evidently hoped would carry it smoothly through the winds of the future.

Gene came up the stairs. He put a pile of papers on a control desk next to the telescope. “The weight!” he said. The Schmidt had been slopping all over the sky (due to loose gears), and Jim Gunn had joked about hanging some lead on it to tighten down the gears. Gene had found a lead weight from a freight scale. He now lifted it from a shelf and hung it from the telescope on a loop
of clear packing tape—Palomar Glue. He patted the Schmidt and said, “This oughta keep the gears tight.” He grabbed the telescope, tipped it over until it pointed sideways, and snapped open two doors on its side. Carolyn handed him a film holder, which contained a circular piece of black-and-white photographic film—a cookie. He stuffed the film holder through the doors of the telescope, locked it in place, and snapped the doors shut. “Ready,” he said.

Carolyn went to the control desk and read off the coordinates of the first exposure. “Right ascension twenty-two, thirty-two point zero.”

Pulling by a hand hole in the base of the Little Eye, he slewed it across the sky, while dials on the wall told where the telescope pointed.

She said, “Declination plus fifteen, forty-seven.” Her words smoked in the cold.

He slewed again. The telescope arrived at the edge of the Trojan cloud, now rising over the ridge to the east.

He sat on a stool, flicked off the lights in the dome. He peered into the eyepiece of the guide scope. He saw a set of crosshairs and a bright star—his guide star. He said, “What’s the magnitude of this star, dear?”

“Six point four,” she said.

The guide star lay near the crosshairs. “It’s pointing to the right part of the sky, anyway,” he said. He took up a control paddle. Hitting buttons on it, he tweaked the telescope until the crosshairs zeroed on the guide star. The telescope was centered on the first exposure. He said, “I’m ready.”

“Five,” she said, “four, three, two, one, open.”

He reached up, pulled a lever, and two shutter leaves on the skyward end of the telescope opened like a pair of unclasping hands.

“Liftoff!” she said.

The telescope’s automatic tracking drive would keep the crosshairs on the guide star while the sky moved and the telescope gathered light. Sometimes the guide star would go
oop
, slip off the crosshairs. Heaven doesn’t jerk; telescopes do. He would work buttons on the paddle frantically to get the crosshairs back on the star before the photograph smeared.

The guide star suddenly kicked away from the crosshairs, and he said, “Bad hiccups!”

“We’re looking east, Gene.”

“It’s horsing around. It’s going all over the lot.”

“That’s a disaster, Gene.”

“Ah, damn!” he said, and there was a sound like
zeee, zeee
while he punched buttons on the paddle. “This gear is worn,” he said. “The telescope is oscillating back and forth.” A flash of blue sparks danced around the telescope’s mounting.

Carolyn said, “You might try putting the weight on the other side.”

He switched on the lights. He put the weight on the other side of the telescope. Carolyn tugged the telescope to the coordinates of the next photograph while he studied a dial on the wall. “The clock could be slipping,” he said. Bob Thicksten had warned him about that. “This is just incredible,” he said.

Carolyn found the cassette player and tuned it to a radio station they liked, which was playing the Beach Boys, who were wishing that all girls could be California girls.

He turned out the lights and started another photograph. “This is awful!” he said, peering into the guide scope. “It’s making huge excursions.” He asked her for the fast-motion paddle. There were two control paddles for the eighteen-inch telescope: slow motion and fast motion. He needed both paddles to rein in this bucking bronco. “This is a two-fisted operation,” he said over odd noises in the dark—
zip, zip, zip, click
—and more sparks fell from the telescope. He leaned back, sighed, and said, “You can see Jupiter.”

Carolyn walked over to the dome slit to take in the view. “It amazes me,” she said, “the way the weather will clear just like that. Looks like there’s fog over San Diego. Good old fog.” Surrounding ridges broke through the fog like the backs of whales.

“We’ll have to get Maarten Schmidt to come up here more often,” Gene said.

They traded places on the telescope, and Gene called off a set of coordinates to Carolyn. She hauled on the Schmidt, pitting herself against it; it weighed half a ton. She sat on a lift chair. Hitting buttons, she raised herself off the floor; the telescope was pointing laterally for this exposure and the eyepiece was hard to
reach. “Horsefeathers!” she said. “I can’t find my guide star. We are way off.” They fiddled around the base of the telescope and finally got it pointed straight. She started an exposure, and the shutters flopped open.

“How’s it treating you?” he asked.

“Not so bad now, Gene. Seems like there’s always a shakedown.”

The trick in sky photography is to get a telescope to track the stars closely while the earth turns. “When the telescope isn’t tracking well,” Carolyn explained, “the stars turn into seahorses and submarines in the photograph.” The Schmidt’s mounting looked like a tuning fork. The telescope’s tube hung between the bars of the fork, and as the sky turned, the handle of the fork rotated to keep the tube pointed at the same place in the sky. Two dials on the wall told where the telescope pointed in right ascension (longitude) and declination (latitude) in a coordinate system known as the celestial sphere. Up until the time of Copernicus, astronomers had thought that the earth hung at the center of this celestial sphere and that the sphere revolved around the earth.

Each exposure lasted four minutes, and when an exposure was complete, the Shoemakers removed the film holder from the telescope, containing a single exposed film, and brought the film holder downstairs to the darkroom to be changed. They kept two film holders cycling, so that one was always inside the telescope gathering light. Next morning, Gene would develop the whole batch of films. As the night advanced, Jupiter set in the west, while the unseen Trojan cloud climbed to the top of the sky. The Shoemakers crossed and recrossed the cloud. They took strings of photographs, lapped at their edges like rows of fish scales. They changed places on the telescope once in a while. Every forty minutes they backtracked the telescope and rephotographed places where they had just been, to make stereo pairs. Anything that had moved during forty minutes would pop into stereo before Carolyn’s eyes when she searched the films. The cold began to bite. Domes must be kept the same temperature as the outside air, since warm air inside a dome would flow out through the slit, rippling around the telescope and causing the stars to twinkle, which would hurt the seeing. A meteor crossed overhead, leaving a greenish, curly trail. Gene looked up from the control desk. “That was a beauty,” he said.