The laboring gangs sped across ice that was gouged and split, great troughs dug deeply into it, cut and formed and hammered. At regular spacings Jim Vidor had erected spindly towers by melting, force-forming, and refreezing water into crystalline struts, levels, braces.

Cobwebbed strands connected jutting, orange-tinged fingers of flash-wedded crystals. Ice had little shear strength, and well only under compression. It was impossible to believe that the arabesques were merely functional. Still, Carl had no doubt that Vidor, if pressed, would be able to come up with an explanation for each extruded, delicate strand, every corbelled arch, all the spindly weaving art of it.

Carl had not asked. Humans could not stick remorselessly to the narrow and practical; anyone of skill yearned to express something deep and abiding through his craftsmanship. Perhaps it was the impulse to leave an idiosyncratic, quirky dab of self on the most enduring things they made. Probably it was something deeper, tied to the spirit that had brought a lone tribe of primates so far out from their own warm, moist world.

Carl remembered the opening lines of a poem Virginia had shown him months before. Somehow they had stuck with him.

The sea is calm tonight.

The tide is full, the moon lies fair.

Omens for good sailing. The poem had something to do with beaches and oceans, and Virginia had sensed some resonance in him for those images. Voyaging out here, sailing against gravity’s tide, resembled the grand old days of seagoing craft. They had tapped a fraction of the sun’s raw photon wind to control the comet’s outgassing, in the first months after landing. Then they ran before that wind, using sunlight only to yield electricity. The crucial time was coming now, when their iceworld craft had to be pushed into a fresh orbit, a new course charted.

He smiled at himself. Clinging to the sea analogy, eh? All because you’re deep in your bones a spacer, and can’t forget it. Ever since losing the Edmund, you’ve been yearning for a ship. This chunk of ice and iron is all you’ve got left.

It was so obvious, Virginia had seen it. She had told him that poetry was a consolation, and to his surprise he had found himself enjoying some of the stuff she transferred into his display. That would’ve been utterly impossible for the brash, self-involved spacer he had been thirty-five years ago. He’d aged only seven years in that time, but that span had a weight of its own. His younger self now seemed distant, almost implausibly blind.

I hope Virginia can’t see too well into me. She’ll find out soon enough how much all this hope and euphoria are false, based on an unavoidable lie …

He didn’t like to recall that. He shook his head and moved across the ice, taking long strides, surveying the work. Keep busy. Don’t think too much; it’s not your strong suit.

Carl circled around a gang of laboring mechs to reach the long trench of Launcher 6. A completed flinger filled the scooped-out, obliquely descending trough. Two engineers were testing a flywheel made from Halley iron.

The machines would deliver momentum at a precisely calculated rate and angle. At first they would fire parallel to the equator, to slow and finally halt Halley’s fifty-hour spin. After that, the launcher would pivot about an axis buried in the trench, bringing it nearly perpendicular to the equator, in line with Halley’s center of mass. Then would begin the long stuttering bursts which would, delivered over years, add minute increments of momentum to Halley’s slow, stately swerve at aphelion. All the launchers, pulsing endlessly, would sum up to the Nudge.

—Real pretty, uh?—

Carl saw Jeffers approaching with an easy, practiced lope. His suit tabard was a crossed pliers and wrench in a cube, stained and spotted.

“Beautiful. Is it tested out? Ready for horizontal mounting?”

—Sure. Sets in there jest fine, any angle you want. Mechs’ll get it duty-mounted soon’s testing’s over.—

Jeffers grinned happily. He was the mainstay of the Nudge, finding solutions to problems with a quick, expert savvy. He worked eighteen-hour shifts without a sign of fatigue. The factory at A Level, humming away now with robos making replacement parts for launchers and rockets, wouldn’t exist without Jeffers. Carl remembered when the man had put in the minimum, wrapping himself in holotapes or pornstims, blotting out the reality of where he was. Work was what he had needed. To Carl, that alone was reason enough to do all this, even if his friend surely suspected that it was all a farce …

—Every crew’s ahead of schedule. Even puttin’ in extra time, without me askin’.—

“We’ve finally got something to work for.” Carl said it without meeting Jeffers’s eye.

—Damn right.—

A manager-mech approached, an extra dome perched atop its carapace in a makeshift kluge. Virginia’s add-ons worked marvelously, making the mechs and robos far more versatile, but they weren’t elegant. The mech winked its lamp to attract their attention and sent,—Launcher 6 complete. Human tech Osaka states that the device is ready, for formal testing.—

Jeffers nodded.—Fire the sucker!—

Warning gongs sounded over the comm line. Everywhere on the surface, teams stopped work and climbed out of pits to watch. Their suits were scratched, worn, discolored, patched with homemade parts.

A ping ping ping of warmup rippled over the comm frequencies, thin ringing echoes of the charging now under way in the trench. Carl peered at the tip of the launcher, which jutted free of the ice nearby, pointing at the sky.

He felt prickly excitement, gathering tension. If they’d made some mistake in the design, in assembly…

A small tremor came through his feet. A rattle in the microwave, a skreee—and the unit discharged.

Simultaneously, a vague haze appeared et the mouth of the launcher. He wondered what was wrong, until he suddenly realized that the firing rate of the flinging tube was several capsules per second— and he was seeing the blur of their passing.

That was all. No roar, no belching smoke. The launchers were designed to operate with near-perfect efficiency, to generate as little waste heat as possible. If even a fraction of a percent of the launching energy seeped into the surrounding ice, it would evaporate away the structural support, producing dislocations, unbalancing the carefully configured momentum-matching of the accelerator segments. Long before the ice was gone, the ratcheting instability of the drive tubes would jerk and thrash them into twisted steel.

But the flinger functioned smoothly. A cheer rose across the comm lines. People raised their arms in victory salutes as far as Carl could see, dancing on the grimy ice, leaping high into the blackness. Only the mechs continued stoically about their tasks, oblivious that humans had at last clasped the helm of this ice ship. Halley was no longer just a tumbling dirty snowball in the long night. She was now a spacecraft.

Jeffers was babbling excitedly, repeating operating parameters as he read them off his helmet display. Carl could follow some of the rapidfire reciting— kilo-amperes surging in low-impedance circuits, voltages building to sharp peaks and then collapsing as each slug passed, leaching the energy of inductive electric and magnetic fields. Energy poured into the capsules, electrodynamic momentum flowing like a fluid at the speed of light.

Only electrical acceleration was efficient enough to avoid the waste-heat problem, to avoid slowly melting the comet itself. For the moment there were ample piles of iron at the north pole, mined in the first year of the expedition, but deep beneath each launcher was a mech mining operation, where in constricted caverns the robots dug and processed more of the comet’s natural, ancient metal.