Donald Moffitt: Second Genesis

The material part of the shaft was its least important aspect. In fact, its tremendous length could not have held up under even moderate lateral stress. It was there to provide support for the winding coils that deflected the roaring streams of ionized hydrogen in their constricted path from the collection area forward to the ignition cage aft.

For a moment Bram tried to imagine what the whole crazy travel arrangement would look like to a hypothetical observer outside the craft—provided that the observer could see by undopplered light. Or, more to the point, provided that the observer was in the same relativistic frame, matching the spacecraft’s course in velocity and direction. Otherwise, the collection of shapes on their long skewer would be foreshortened by a factor of twenty thousand, turning them into a stack of paper-thin disks pierced by a thumbtack.

He decided it would look like a post horn straddled by a leafy dumbbell.

Bram had seen a post horn once, at one of Olan Byr’s memorial concerts. The ancient instruments, from lyres to sousaphones, had been part of Olan’s legacy. He had been tireless in commissioning reproductions from hints in man’s digitally transmitted art masterpieces, dictionary sketches, and clues in the musical notation itself. The post horn was based on one played by an angel in an Annunciation. It was a long, straight tube of brass, tall as the man who played it, with a flaring bell at one end and the smaller flare of a mouthpiece at the other.

Bram closed his eyes for a moment and savored the eccentric image.

The post horn that dragged Yggdrasil by the collar was twelve hundred miles long, with its slender tube aligned along g forces to keep it straight. The bell was an insubstantial net of superfilament, several hundred miles in diameter, that kept its shape by virtue of an independent spin at its rim. Around the bell was a multicolored cascade of sparks, like trumpet notes made visible. A miniature sun burned blindingly in a magnetic cage at the mouthpiece, like a divine breath. And from the flared mouthpiece issued a thin pencil of inspired light as the hadronic photons, their work done, decayed and wreaked havoc with whatever interstellar debris was still left behind in the wake of the probe’s sweep.

Pleased with the image, he conjured up the other component of the queer hybrid vehicle.

Yggdrasil would make a compressed sort of dumbbell, he decided, with a short, thick handle and rather flattened hemispheres. More like a pair of fat wheels lying athwart the long axis of the probe. One hemisphere was silver with a green rim facing the fusion fire. The other was brown, laced through with the crystal sparkle of cometary ice and showing an arc of green where Yggdrasil’s root system had decided to help out with the photosynthesis.

The looming reality of a wall of foliage rushing past him only a few miles away dissipated the image, and Bram turned his eyes to the view he loved best.

Between the rushing walls of Yggdrasil’s twin hemispheres, a spectacular slice of sky was visible. A rainbow of stars made a dazzling arch across the void. Optical effects had crowded the bands of color so close together that the effect was like strands of matched jewels, jumbled together in overlapping profusion.

It was so beautiful that it hurt.

Bram studied the ribbon of stars. Was it narrower than the last time he had looked? It was hard to tell. But the yellow band seemed to have moved a degree forward, and the dull, ominous blanket of reds that faded into the blind spot seemed to have been dragged along by the rainbow hem.

A star whizzed by, changing from purple to blue to green, then to yellow, orange, and red before it was swallowed by the blind spot.

The star must have been very close—only a few light-days away. At the present gamma, Yggdrasil swept across a light-year in about thirty minutes. That was fast enough to make the nearer stars move at a crawl, changing their colors as they lined up against the background rainbow.

A second violet star popped out of nothingness, riffled through the spectrum, and vanished to the rear.

The first star’s companion! Yggdrasil was skirting a double star system.

Bram tried not to worry. Even here in the depths of the galaxy the stars were light-months apart. A collision would be most improbable, Jao had assured him. Even if Smeth’s instruments were to show Yggdrasil heading straight toward a star emerging from a dust cloud, there would be minutes—perhaps hours—to change course. A lateral nudge of less than half a degree, projected over a minute or two of travel, would always give them margin to spare.

He drank in the glittering, spectacle again, wondering how much longer he would be able to enjoy it. As Yggdrasil’s speed increased, eventually the stellar rainbow would shrink into a thin gold rim framing the forward blind spot, and the vortex of hydrogen influx would make it invisible from any part of the tree. He had tried to get a time estimate from Jao, but Jao had been vague. They were slicing the remainder of the speed of light so thin at this point, Jao said, that measurements were meaningless.

He looked up through the top of the pod and saw the trunk rushing toward him. A cluster of external housings was directly above: upside-down bubbles with suspended catwalks. Ten or twenty miles to his left, he saw a portion of the tremendous crystalline girdle that circled Yggdrasil’s waist and the secondary tether that would keep Yggdrasil from sliding forward along the shaft during deceleration mode. The tether was of woven viral monofilament a half mile thick, and the double bowline knot that fastened it had been tied, with much tricky maneuvering, by a pair of space tugs. Tension would only make it stronger; with the enormous forces involved, nobody wanted to take chances with extraneous fittings.

Bram noticed that at the moment Yggdrasil was floating free within its circlet; its momentum was temporarily matched with that of the probe.

The trunk filled his view, and then the taffy pull of the counterline slowed the travelpod to a bobbing stop about a half mile below the entry blister.

Bram uttered a mild expletive as he found that the fist-size electric trolley that was supposed to wind him in the rest of the way was out of order.

For a moment he was tempted to exercise a year-captain’s prerogatives and signal the hub to reel him in. But he was only a couple of hundred feet from his destination, and the pod’s weight was negligible added to his own, even under one-g acceleration. A half hour’s worth of muscle power would do it.

With a sigh, he bent to the two-handed windlass and began cranking.

“That ought to do it,” Bram agreed.

He tore his gaze away from the massive helical housing of the high-capacity pump. There was a final gurgle that shook the floor as the last of a half million gallons of chemical solution was forced deep into Yggdrasil’s sapwood.

The tree systems officer and her hovering assistant gave him bland stares. “I thought the best way to calm Yggdrasil down would be to smooth out the peaks and valleys in phytochrome balance,” the TSO said with professional briskness. “There was too extreme a swing between the two pigment forms, and it was driving Yggdrasil crazy.”

She gauged his expression for signs of comprehension, apparently decided in his favor, and went on. “You see, the problem is the growing Doppler shift. Unfortunately, all the far-red light comes from the same direction as the fusion light, so that side of the tree’s overstimulated. The phytochrome keeps changing back and forth between the far-red-absorbing form and the sunlight-absorbing form, then back again.”

Her assistant, even younger than she was, nodded agreement. They were both being patient with the old dodderer.