The Genesis Quest

by Donald Moffitt

  Kerthin did not rise to the bait. Bram knew that Trist had overheard her remark about migration and was teasing her.

  “You may have something there,” Bram said, keeping his voice serious.

  “Sure, back to the treetops after forty million years,” Trist said.

  The boat’s attitude jets coughed diffidently, and the cabin made a quarter rotation. Bram’s orientation changed. He was no longer looking down at a floor of roots, up at an umbrella of leaves. They were now the walls of an impossible chasm, and he was looking up through the top of the viewdome at it.

  This time his senses agreed with his intellect. What he viewed as “up” was “up” for the tree, too. One hundred and fifty miles over his head was the axle that spun the twin disks.

  Others had the same thought. “There’s the trunk,” Trist was telling Nen. “Can you see it?”

  Bram peered straight up at the slice of night visible between the two living walls. The trunk could be seen as a mottled gray bridge that joined them. It was as straight as centrifugal force had grown it, except at either end, where it fanned out gracefully to give rise to the circles of reaching growth.

  The thrusters gave the hovering craft a measured kick and sent it rising up the living canyon.

  “It’s a yo-yo,” Trist said suddenly.

  “Huh?”

  “The tree is shaped exactly like a yo-yo. Didn’t you ever have one when you were a child? And now I bet I know how we’re going to get transferred to the rim.”

  It took another hour to reach the trunk. For the last twenty miles, the pilot sent the craft rolling and timed each small burst of the braking jets for the moments when he was pointed toward his destination. He finished up nicely with his trimming nozzles aimed for the vertical — compressed gas jets that wouldn’t hurt the tree.

  The tumbling had disoriented some passengers and produced nausea. Somebody across the way was being sick in one of the pinchbasins that had been provided for that purpose. “First casualty,” Trist said.

  Bram looked at Kerthin. Her face had gone the color of putty, but she swallowed hard. “So much for the consideration of your five-legged friends,” she said.

  “Be fair, Kerth,” he said. “This is the way they always do it. The Nar don’t get motion sickness with their kind of nervous system. They can’t change their touchdown routines just because they’ve got a load of human passengers.”

  “Or maybe they could, if it had occurred to them,” she said angrily.

  The tree trunk hovered overhead, a solid wall of patchy gray bark. Bram could see Nar in space suits clinging to it, moving like disembodied claws along the surface. They didn’t seem to be at all inconvenienced by the fact that they were hanging upside down off a spinning cylinder that could hurl them off into space. This close to the center of rotation of the tree, centrifugal force was so small as to be almost negligible. If one of them lost his grip and started drifting outward, he would have ample time to make a grab for it.

  And the Nar were better suited for space work than humans, anyway. Even leaving the prehensile legs aside, they could hold on with two arms and still have three to work with at any given moment.

  Two of the space-suited figures deliberately broke contact with the rough expanse of the trunk. Several passengers gave a gasp as they saw them drifting downward like five-pointed snowflakes.

  But not quite. One of them was trailing a gossamer cable attached to a great curved hook cradled between two of his tentacles. Bram followed the line with his eyes to where it ran back to a massive spool mounted within a skeleton housing on the bare trunk. There were several bubble structures seemingly growing out of the bark at that point, and dozens of space-suited Nar swarmed around the spot.

  The two decapods landed with the tiniest of jolts on the overhead dome and clung to one of the radial struts that framed it. Some of their momentum must have been transferred to the passenger craft, but it was so relatively slight that Bram, though he was watching for it, could not detect any alteration in the boat’s hovering position.

  The workmen waved at the passengers inside the cabin and got friendly waves in return. They set about attaching the hook to the large ring at the top of the dome where the struts met. Bram had noticed the ring when he had boarded the vehicle, but he hadn’t been able to figure out what it was for. He had thought it might be an antenna.

  The cable that he saw looping away from the hook did not seem particularly thick. It was about the diameter of Bram’s thumb. But if it was made of the same long-chain viral filament thread that was used for bubble car trams, then it had strength to spare.

  The space-suited pair got the hook attached, then retreated hastily along separate struts to the perimeter of the cabin. They were showing the cable a lot of respect.

  The looping thread slowly straightened itself out. So some of the workmen’s momentum had been transferred to the boat. Bram glanced at the trunk overhead and saw that it was indeed some tens of meters farther away.

  There was the smallest of jolts as the last of the slack was taken up, and the passenger boat began a pendulum swing that carried it to a point below the opposite side of the giant spool above and then back again. The cable must have been winding out somewhat to ease the shock, because Bram could see the ceiling of bark retreating farther before there was a final jolt. And now, he realized, he weighed something again. Not very much — probably not more than a few ounces. But it was funny the way the body could tell.

  In the seat ahead, Trist was testing the sensation by letting a small object from his pocket drift to the floor and timing its fall. “Don’t mind me,” he said cheerfully. “We physicists are a compulsive lot.”

  The work crew above reeled them in partway so that the hook handlers would have less distance to climb. The pair gave a final wave to the occupants of the cabin, then swarmed up the cable.

  The boat hung there for some minutes while the pendulum motion damped itself out. The Nar attendant had a dialog with the pilot through his glove. Then the descent began.

  Yes, Bram agreed, it was an eminently simple and straightforward way to match rotational forces gradually with the outermost branches. And yes, it promised to be an interesting experience.

  The attendant was being bombarded with questions from his passengers.

  “What happens if the line breaks?”

  “It never has.”

  “Yes, but what if?”

  The Nar laughed: an explosive exhalation of air from the modified alveoli that formed the vocal syrinx. “The transfer vehicle can develop accelerations of up to one-fifth gravity. At this point we could easily cancel the outward motion. We would simply start over again.”

  “What about when we pass the one-fifth-g mark?” This was from Trist, pausing in his experiments to help the attendant with his lecture.

  “There are crews waiting at the rim who could snare us and reel us in. If worse came to worst, they would send a rescue ship after us at several g’s acceleration. Our direction would be along a choice of degrees in the known plane of a circle. They would catch up in a few hours. I assure you there is no danger.”

  Everybody was watching the wall of greenery slide by, some twenty or thirty miles to the side. Bram could pick out no details at this distance other than the half-buried contours of the main branches, radiating outward like gargantuan spokes. If there were any artificial structures tucked among them, they were invisible to the naked eye.

  Trist whistled. “If you hollowed out just one of those branches it could house a population of millions. Hmmm. Think of it as a tower, a hundred fifty miles high and maybe five or six miles in diameter at the roof and tapering to a half mile at the base. Conic sections. Remember your middle school math? Figure fifty-foot levels — fifteen thousand of them, with a floor area of … care to do the honors, Bram, old chum?”

  “They don’t use the branches,” Kerthin said unexpectedly. “Except for travel tubes and way stations. They leave the tree mostly alone. It’s
a life-support system. It has to stay healthy. They probably use less than one percent of it. The trunk for low gravity. And the tips of some of the twigs and branchlets for living space. But its mostly wild growth in between.”

  Bram looked at her in surprise. “I didn’t realize you knew so much about star trees,” he said. “I thought you weren’t interested.”

  “Oh, I heard someone talking about them,” she said, and fell silent.

  Some of the other passengers were still pestering the attendant. “When we reach the end of the line, we’ll be dangling in midspace, between the roots and the crown. Miles and miles from anything. What happens then?”

  “Wait and see,” the Nar said.

  Kerthin made a disgusted sound. “More guessing games,” she said.

  The boat picked up speed as the cable unwound, almost — but not quite — failing. Descent had to be somewhat slower than what would have been the normal rate of “fall” in order to maintain tension on the cable. The differential was great enough to give the passengers noticeable weight — weight that increased proportionally — as the great circle around which they were being swung grew in diameter.

  They had not made a full revolution when the line played out, buffered by the skill of the winch operator one hundred and fifty miles above them and by the elasticity of the viral filament itself.

  The boat swayed gently at the end of its line, an upside-down captive balloon straining for the stars. Everybody craned for a look at the strange, green, topsy-turvy horizon that was their destination.

  Its curvature was quite noticeable, of course, dropping off sharply in either direction. But the diameter of the foliage crown still put it in the same class as a good-sized planetoid.

  Or would have, if it had been a complete ball instead of an oblate hemisphere. The boat was suspended midway between two such slices of world — the halves of a yo-yo, as Trist had described the shape — and it was rather like hovering within some enormous canyon. A canyon with a log bridge across it halfway up and stars at the top and the bottom.

  “Yggdrasil,” Trist said.

  “What?”

  “Don’t you know your Norse mythology? Yggdrasil, the world tree.”

  “There are so many different legends,” Bram apologized. “I’m afraid they all got mixed up in my head when I was a child.”

  “Its roots spanned the earth and the heavens,” Trist said. “And when at the end of the world the universe was devoured by fire, a new race of men emerged from its wood.”

  “Thoughtful of Original Man to give it to us, then.” Bram laughed. “But you’ve got the story wrong. We emerged from radio waves.”

  “The tree could nourish us through a transition, though, couldn’t it?” Nen said, joining in. “Yggdrasil was supposed to have given the water of life.”

  “Well, this one will certainly do that for the Juxt One colonists,” Bram said.

  “Look, they’re coming for us,” Kerthin said, touching his arm.

  Bram followed her gaze and saw a bright dot of flame perched on the inverted horizon. It moved to a point fractionally within the green arc, burned for another minute, and winked out. He kept his eyes on the spot where it had been, trying to hold his line of sight, and after a few minutes was rewarded by the appearance of a polyhedral framework that had moving dots clinging to it. The dots resolved themselves into a Nar work crew dressed for space.

  Some day, Bram thought, someone would design a space suit for humans — if humans ever became numerous enough to be more than mere baggage! What would it look like? It would have to have a transparent dome at one end, for the head. Accordion joints for knees and elbows. Twisting around might be awkward. The Nar anatomy was better designed for space. A Nar space suit looked for all the world like two silvery gloves joined by a transparent wristlet that provided 360-degree vision. No sore necks for them!

  The service frame floated past at a respectful distance. Why weren’t they braking? Of course! For the same reason they weren’t being swung outward by the line they must be trailing. Having canceled their own centrifugal motion with respect to the tree, they wanted nothing to do with the one-g force the passenger boat had picked up during its long unreeling.

  Bram squinted and confirmed his guess. The line the service frame was hauling behind it had plenty of slack, bellying outward at an arc that must have carried its invisible portion at least fifty miles into space. Though tethered at its point of origin, and obeying the laws of physics itself, the minute tug it exerted had not yet materially altered the trajectory of the service frame.

  The passengers waved as the frame drifted by, but the work crew was too occupied to wave back. “Why aren’t they stopping?” Kerthin asked.

  “You’ll see in a minute,” Bram said.

  “Oh, good gods, you too?” she exploded.

  A Nar crewman clinging with all five legs to the putative top of the polyhedral frame was swinging a length of free line with a grapnel hook attached to it around and around his splayed top. Skillfully he played out the line little by little, keeping it safely away from the outward-looping portion of the cable. He’d timed the arcs nicely. Bram watched as the line intersected the cable from which the passenger boat was dangling and wrapped itself around it. The grappling hook fetched up against the cable in a final spasm of angular momentum, and then the low-friction filament began to slide. The Nar roping artist hauled in smartly, keeping tension on the unwinding line until the grappling hook engaged. Now the service frame moved outward with a quick spurt of its jet, while the Nar let the guy rope slide through his grip. The bellying line, whose far end was attached to the rim of the tree crown, straightened out as somebody began to winch it in.

  The Nar lasso specialist let go at the last possible moment and allowed the line to twang taut. The little shiver of momentum was hardly noticeable within the passenger cabin; the tether lowered from the trunk had already matched g-forces.

  It took the high-speed winch at the rim less than a quarter hour to reel the boat in while the service frame followed behind. Willing tentacles snagged the lines and made them fast. It was a primitive way to bring in a spacecraft for docking, but when he thought it over, Bram had to concede that it made sense. It was simply the application of known forces, just as was maneuvering by rocket power. In fact, brute muscle power and simple mechanical forces were probably more accurate and economical. It was a good thing the Nar hadn’t forgotten the skills learned in their days of wind-driven sailing vessels.

  The boat was resting on a wooden ledge carved out of the trunk. When the Nar ground crew was satisfied that all was secure, they cast off the hawser bound to the faraway trunk. Released from its vector of forces, the cable began a slow pendulum swing outward.

  The boat was winched from the ledge into a dome-shaped vacuole that was a hundred feet across. Airtight hangar doors in the shape of vast triangular sections flapped shut and sealed at the center. Air billowed into the vacuole with a force powerful enough to rock the boat and knock one unwary Nar workman off his tentacles before he could latch on to something. Bram knew it was safe when the Nar crew began peeling off their double-ended space suits. A moment later the flight attendant announced that they could leave the vessel.

  A welcoming committee was waiting for them inside the next chamber: a half dozen men and women in scanty shipboard attire. They looked for friends among the several dozen disembarked passengers and in a few minutes were exchanging multiple embraces.

  Orris and Marg had not been among the greeters. Trist’s friend Lilla was, and Trist and Nen were babbling eagerly at her. Bram took the opportunity to look around the chamber he was in.

  It was vast — bigger than the vacuole that had been converted into an air lock. The tree’s simulated gravity had forced a generally domelike shape, and the floor was fairly flat, with a little help from carpenters. The dome overhead had a burnished velvety sheen, lovely in the glow of the biolights that seeded the chamber. The air was clean and forest-fresh.
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  “What do you think of it?” he asked Kerthin.

  “What did he call it — the world tree?”

  “Yggdrasil,” Bram said.

  “It’ll do,” she said, quite seriously. She sounded like a prospective buyer considering its merits.

  “Do for what?”

  She presented a face to him that was totally devoid of humor. “As a way to start a new world,” she said.

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  Chapter 8

  Over a thousand people were gathered in the hall of the tree, embarkees and guests, but they seemed lost in hugeness. There were too many echoes, spoiling the spontaneity of the party noises that some of them were trying to make. A few small clusters, mostly twosomes and foursomes, were thinly dispersed across the immense woody amphitheater, but the majority had drawn instinctively into a loose concentration along the part of the wall that held the bar.

  “This is going to be a farm chamber when we’re fully outfitted,” Marg said, “but the party committee thought it would be a good place to hold the bash. I told them it was too big, but they wouldn’t listen to me. We could have used one of the smaller vacuoles nearer the surface and had a view of the stars to set the mood.”

  She locked eyes with Bram, waiting for his agreement. Men tried hard to agree with Marg. She was plump and pretty, with wide ingenuous eyes. She was wearing a cleverly simple sleeveless dress that showed a generous expanse of her glowing skin.

  Orris, a knobby beanpole in shorts and singlet, hovered at her side, looking proud and possessive and overwhelmed. “You remember Marg’s theory of how to throw a really good party,” he said. “Crowd people together in a space that’s a little too small for them. Make ’em rub elbows. Make sure there aren’t enough seats, so they can’t take root. Force ’em to circulate. And keep the lights low.”

  “It’s so bright in here,” Marg said. “I’m going to try to get them to shut down the pumps for the overhead tubes circulating the biolights.”

  Bram smiled sympathetically and looked around. The lens-shaped cavity was still unfinished. The distant end, leading to the hollowed-out resin canals that had brought them from the outside air lock, still needed a lot of scraping and polishing. Marg was right about the size; the party decorations dangling far overhead looked remote and forlorn.