Chapter 12.

From less than a quarter million miles away, the alien ship showed its form starkly through the telescopes. It swam against the luminous striations of Jupiter, an angular, many-armed silhouette. The shape was peculiar. It wasn't designed the way humans would have done it, but it made sense.

Picture a slender rod fifteen miles long-slender only by virtue of its enormous scale. It had to be at least three miles in thickness. Radar echoes had shown its cross section to be an equilateral triangle-a three-sided stick. The echoes also must have told the aliens that someone was looking at them.

From the tip of the rod, three long arms sprouted sideways making the shape of a Y. Each of the arms was fifteen miles long. Folded back along the rod, they would just about have reached its opposite end.

Each arm ended in a prism. The cross section of the prisms was the same as the rod-an equilateral triangle three miles on a side. They were in effect shorter slices of the rod, measuring four and a half miles from triangular face to triangular face. The arms with their clubbed ends twirled lazily, a whirligig for t.i.tans.

There were five of the great ships, cl.u.s.tered in a pentagonal formation, revolving around a common center of gravity. But this one, etched against Jupiter's roiling clouds, was easiest to see.

Jameson tore himself away from the eyepiece reluctantly and levered himself across the observatory to join the rest of the group. They were gathered around a large projection screen which reproduced the telescope image, but it wasn't quite the same as seeing it firsthand.

"It's obvious," Pierce was saying. The young astronomer was flushed with excitement, talking too rapidly. "The long shaft is their drive section. In flight, those three arms fold back along the shaft like the ribs of an umbrella. Those nice flat surfaces are meant to rest against the three faces of the shaft."

He stopped, out of breath, and glanced apologetically at Ruiz.

"Go on," Ruiz said. "You're doing fine."

Pierce ran a hand over his mussed hair. "But when they'renot accelerating or decelerating," he said, "the arms open out and spin to give them artificial gravity. Those wedge-shaped modules at the ends of the arms are the environmental pods."

"Environmental pods!" Chu exclaimed. He sucked on his wispy moustache. "Look at the size of them!

They're-they're worldlets!"

"To think of engineering on such a scale!" Li said admiringly. "Supporting ma.s.ses like that on ten-mile booms!" He flashed a disingenuous smile in Jameson's direction and said, piously, "They must be socialists.

That earned him a suspicious stare from Tu Juechen. She sucked in her pleated cheeks and fixed him with her little monkey eyes. Li met her gaze innocently. The Struggle Group leader had shown up shortly after Jameson and Li had arrived and had been glaring at everybody since then, poor Dr. Chu most of all.

Jameson couldn't imagine why she was there. It wasn't any sort of formal meeting. Ruiz had called him up when he was turning the bridge over to Kay Thorwald, and asked him if he'd like to drop by for a look at the alien ships before he went back to the spin section. The ships had just emerged from behind Jupiter in the complicated sixteen-day orbit they shared with the Cygnus Object's former moon, and Ruiz had promised him a more spectacular view than last time. On the way back to the observatory he'd b.u.mped into Li; who'd immediately asked if he could tag along.

Jameson got Li off the hook by quickly saying, "Djen hwa. As you say, the engineering's on a tremendous scale. Besides swiveling the asteroid-size modules outward on the ends of those booms, they've got to manipulate them so that they're turned around."

"Yes, yes, of course!" Pierce cried. "My G.o.d, I didn't think ofthat! "

Tu Jue-chen looked from one to the other of them, a simian frown creasing her brow. "I do not understand," she said.

"Whattongzhi Jameson means," Dr. Chu said hastily, "is that the pods must bereversed when the arms are rotating. Otherwise the centripetal force that subst.i.tutes for gravity would be in the wrong direction.

The pods would be 'upside down.'"

"You're a.s.suming that the booms are attached at therear of the drive section?" Ruiz said.

Chu gave a little bow. "Of course. The three arms would fold forward, to put the environmental pods as far away from the drive as possible. Fifteen miles away from it, in fact. We do not know what energies these creatures must command to travel at nearly the speed of light, but we can a.s.sume that they are dangerous."

"And," Pierce interrupted breathlessly, "when the arms are extended, the pods arestill fifteen miles from the drive-at right angles, of course. In case there's any danger from lingering radiation, I suppose."

"Yes, yes," Chu said, looking annoyed. "The point is, when they're accelerating, or turned around to decelerate, their artificial gravity is in the direction of their line of flight. Otherwise, they get it from spin, just as we do."

"Which proves," Ruiz said, "that if such a thing as true 'artificial gravity' is possible, the aliens haven't discovered it."

"But they're so far in advance of us-" Pierce began.

"Are they?" Ruiz said. "They do things on a larger scale. That's all we know so far."

"That's putting it mildly," Jameson said. "Moving whole worlds about! Building a fleet of ships larger than the Martian moons..."

Ruiz looked pensive. "Maybe there's no other way to do it. When you're traveling between the stars, you don't go home again. Not after ten thousand years. You take your whole society with you"?

Interest flickered in Tu Jue-chen's close-set little eyes. "How many of these creatures do you suppose there are aboard those vessels?" she asked.

Ruiz nodded at Pierce. "Do you want to take a crack at it?"

"Hmm. Let's a.s.sume that they're roughly our size. Somewhere between twice our size and half our size.

There must be an optimum size range for intelligent life. Much smaller than that and they don't pack enough brain tissue. Much larger and they become unwieldy. Specialized-"

"There are whales," Li said mischievously. "And elephants."

Pierce looked disconcerted. "Hmm, yes. But I can't see a gigantic sea creature developing into a s.p.a.ce traveler, no matter how intelligent. The early steps would be too difficult. Besides, it's hard to imagine those pods as giant aquaria, sloshing around with liquid. The amount of ma.s.s involved, for one thing-"

"But very large land animals," Li pressed him. "From low-gravity planet. s.p.a.ce travel would be easy in early stages. And pods are rotating very slowly. At one third gravity, is it not correct?"

Maybury had joined the group un.o.btrusively, her arms full of stacked photographic plates. "But when the Cygnus Object was approaching the solar system, Dr. Ruiz noticed that it was braking at nine hundred and eighty centimeters per second per second," she said gravely. "Approximately one g for a sustained period of time. Perhaps they spin their ships at less than normal g-force for the same reasons we do."

Pierce nodded gratefully. "Yes, yes," he said. "We're getting away from the subject. We can a.s.sume anything we like, but for the sake of convenience, let's a.s.sume that they're in a normal size range for highly evolved terrestrial animals.-"

"How many creatures?" Tu Jue-chen said tartly.

"Yes, I'm getting to that," Pierce said. "Let me see if I remember my geometry. At three miles to a side, an equilateral triangle would have an area of approximately four and a half square miles. Now, how many levels in one of those pods? Let's be conservative and a.s.sume fifty-foot ceilings. Room for an ecology, with the equivalent of trees and so forth. That gives more than one hundred levels per mile of height..."

"One hundred and five," Chu said pedantically. "And six tenths."

"Yes... I mean,shih ," Pierce said, fl.u.s.tered. He floundered a moment and went on. "Now, I'm going to be conservative again and a.s.sume the same volumetrics as our own ship. That is to say, the Cygnans occupy only the lower three miles of their pods, and leave the top third for storage, machinery, s.p.a.ce-intensive hydroponics, and so forth. That gives us three hundred-"

"Three hundred and sixteen point eight," Dr. Chu said severely.

"-levels, each with an area of four and a half square miles. That works out to..." he floundered again.

"One thousand four hundred and twenty-five square miles per pod," Maybury supplied. She looked straight at Chu. "And point six," she added.

"Thank you, Shirl," Pierce said gratefully. It was the first time Jameson had heard Maybury's first name.

He saw her glance over at Ruiz. Ruiz was standing straight, arms folded, scorning the no-gravity crouch the rest of them had adopted, looking straight ahead at the screen.

Maybury reached around to the rear pocket of her shorts and took out a pocket lightpad, which she gave to Pierce. A few of the plates got away from her, but she corraled them with little fuss. She'd improved tremendously at handling herself in zero-g in the last few months.

Pierce scribbled on the lightpad, letting it do his sums. It kept flashing question marks at his poor handwriting, and he had to erase and write over again several times.

"Now," he said, "we've got three pods per ship; That's four thousand two hundred and seventy-six point eight square miles of deck s.p.a.ce. And we've got five ships. So the Cygnans inhabit an area of twenty-one thousand three hundred and eighty-four square miles."

Ruiz turned round with a smile. "Fine," he said encouragingly. "Now who knows anything about population densities?"

"I looked up some averages in the ship's library, Dr. Ruiz," Maybury said hesitantly.

"Go on," he encouraged her.

She cleared her throat. "Well, it would be densely populated, wouldn't it? You wouldn't waste s.p.a.ce in a s.p.a.ceship. No swamps or deserts. Places like England or the Netherlands have populations of over a thousand per square mile. In urban areas, like the Houston-Dallasworth megalopolis, it goes up to ten thousand. And inreally crowded places, like Hong Kong, it can go up to two hundred thousand people per square mile."

"Let's stick with ten thousand," Ruiz said dryly.

Pierce stared wonderingly at his lightpad. "That would mean that there are more than two hundred million Cygnans out there."

They all turned instinctively to look at the silhouetted shape on the screen. With nothing to give it scale, it resembled nothing so much as a collection of jackstraws.

Ruiz nodded. "Or, to take the lower and upper ends of Maybury's scale, anywhere from twenty-one million to four billion individuals."

"But why?" Pierce breathed. "What did they come here for?"

"An army!" Tu Jue-chen said, her eyes glittering. "A-a-" She hesitated. "Ch'in lueh che!"

"An expeditionary force," Jameson said helpfully. She nodded.

"Colonists," Pierce said. "Weknow they're doing something to Jupiter."

"Refugees," Chu said, peering over his gla.s.ses. "They left their world because it was dying."

"Maybe they are not leave their world behind," Li said. "Maybe they take it with them."

"The Cygnus Object?" Ruiz said.

Li nodded.

"Mizz Maybury," Ruiz said, "let's have a look."

She moved to the instrument panel. The image on the screen shook. There was a blurry twitch as the telescope's aim swept past the alien fleet, past the kidnapped moon it was circling, to the black void a million miles to the left of Jupiter.

The blurs resolved themselves into the Cygnus planet, a sooty ball which was crowding Callisto on the elliptical orbit which intersected the path of its own former moon. Now it too was a moon of Jupiter-the biggest of them all. It was making a mess of the orbits of its stepsisters.

"Bring it up to maximum, will you?" Ruiz said.

The ball sprang toward them, filling the screen. Jameson looked down through wisps of hydrogen clouds at the face of h.e.l.l.

It was a bleak, rocky desert, split with deep cracks from the tidal forces which were trying to tear it apart. The cracks steamed with noxious gases being squeezed out of the interior. Some of the cracks looked to be hundreds of miles wide, and G.o.d knew how deep-canyons that dwarfed anything on Earth. When the Cygnus planet came to its final equilibrium-if Jupiter didn't break it up first; the observatory computer was still trying to make up its mind about that-the shifts and grindings of these gravitational wounds would sculpt that world's only features.

It had no others. There were no craters, as on other airless worlds, no sea basins or continents or mountain ranges. It was a world without geology, a world that had never been born. It had come out of the cosmos as smooth as an egg, and Jupiter had cracked it.

"Rock," Ruiz said. "Bald rock and the traces of a hydrogen atmosphere. Nothing ever lived here." He turned to Li and shook his head. "This isn't the Cygnans' home planet."

"Why did they bring it along then?" Jameson said.

"Mizz Maybury," Ruiz called out. "Swing the telescope back to Jupiter."

Another million-mile twitch, and Jupiter was back on the screen, a vast marbled presence. The three-p.r.o.nged shadow of an alien ship lay across it like an insect claw. The bands of colored clouds seethed and boiled, flowing visibly toward the equator. The familiar horizontal belts of Jupiter had been gone for some weeks now, replaced by these convolving streaks. Local eddies swirled in thousand-mile curlicues, a meteorologist's nightmare. Jameson could barely make out the pale pink splotch that once had been the Great Red Spot. It had shrunk to a fifth of its former size, and it was leached of color.

Maybury panned slowly across the cloudscape till she came to the edge of s.p.a.ce. The bracelet that Jupiter had been wearing lately showed as a thin bright line etched against the ebony void.

"I'll tell you why they brought it along-" Ruiz began.

An alarm sounded stridently, and the ship lurched. Jameson felt this feet press against the observatory floor with about a hundredth of a g. He had weight now-about a pound and three quarters of it.

Tethered objects in the room began to settle toward the floor. The ship had begun the final braking maneuver that would swing it past Callisto and put it in orbit around Jupiter half a million miles beyond the fringes of the radiation belt.

Ruiz opened his mouth again, but before he could speak, there was a shriek from Tu Jue-chen.

"Huo-hua!" she gasped, pointing. "Lights!"

Jameson turned with the rest to stare out the curved view window.

Out there in the blackness, a thousand fireflies glowed and pulsed: a swarm of small vehicles coming toward them. They were too far away for details to be seen, but they were moving fast. It was an enormous phosph.o.r.escent cloud against the deep of s.p.a.ce.

Maybury got a telescope pointed at the swarm. Blurred shapes bounced back and forth on one of the overhead display screens. Jameson craned his neck, trying to make sense out of the irregular contours.

And then the image compensator had one of them pinned down, and Jameson caught his first glimpse of a Cygnan. It quivered on the screen, a sleek many-legged shape clinging to a stick, like a lizard on a broomstraw.

Ruiz was beside him. "They've decided to notice us," he said.

Chapter 13.

Half the crew was crowded two and three deep against the long, curving observation rail, with more men and women pouring into the bridge's lower level every minute. The Chinese and American fusion/fission teams were still at their posts in the tail of the ship, and Brough and the rest of the medical staff had elected to stay with their patients in the ring, but it seemed that everyone else who didn't have a station to tend had jammed into the ship's command center, with Boyle's and Hsieh's tacit consent.

At a time like this, you wanted to be with other members of your species.

To the naked eye, the Cygnans were still nothing more than a cloud of campfire sparks in the void, but they were coming fast. The big observation screen forward occasionally fixed a brief glimpse of a blurred individual form; Pierce and Maybury had stayed below in the observatory to work the telescopes, and they were piping in their images.

"They're traveling a quarter million miles on those broomsticks, without a ship around them," Ruiz said.

"They must be used to s.p.a.ce."

"How long will it take for them to get here?" Jameson asked.