Redemption Ark

The comet was large, as swarm members went, but not unusually so: there were at least a million that were larger. From edge to edge it was a twenty-kilometre frozen mudball of nearly black ice; a lightly compacted meringue of methane, carbon monoxide, nitrogen and oxygen, laced with silicates, sooty hydrocarbons and a few glistening veins of purple or emerald organic macro-molecules. They had crystallised into beautiful refractive crystal seams several billion years earlier, when the galaxy was a younger and quieter place. Mostly, though, it was pitifully dark. Epsilon Eridani was merely a hard glint of light at this distance, thirteen light-hours away. It looked scarcely less remote than the brighter stars.

But humans had come, once.

They had arrived in a squadron of dark spacecraft, their holds bursting with transforming machines. They had covered the comet in a caul of transparent plastic, enveloping it like a froth of digestive spit. The plastic had given the comet structural rigidity it would otherwise have lacked, but from a distance it was all but undetectable. The backscatter from radar or spectroscopic scans was only slightly compromised, and remained well within the anticipated error of Demarchist measurements.

With the comet held stiff by its plastic shell, the humans had set about sapping its spin. Ion rockets, emplaced cunningly across its face, slowly bled it of angular momentum. Only when there was a small residual spin, enough to ward off suspicion, were the ion rockets quietened and the installations removed from the surface.

But by then the humans had already been busy inside. They had cored out the comet, tamping eighty per cent of its interior volume into a thin, hard shell that was used to line the outer shell. The resultant chamber was fifteen kilometres wide and perfectly spherical. Concealed shafts permitted entry into the chamber from outside space, wide enough to accept a moderately large spacecraft provided the ship moved nimbly. Berthing and repair yards festered across the inner surface of the chamber like the dense grid of a cityscape, interrupted here and there by the cryo-arithmetic engines, squat black domes which studded the grid like volcanic cinder plugs. The huge engines were quantum refrigerators, sucking heat out of the local universe by computational cooling.

Clavain had made the entrance transition enough times not to be alarmed by the sudden whiplash course adjustments necessary to avoid collisions with the comet’s rotating husk. At least, that was what he told himself. But the truth was he never drew breath until he was safely inside or out. It was too much like diving through the narrowing gap in a lowering portcullis. And with a ship as large as Nightshade, the adjustments were even more brutal.

He entrusted the operation to Nightshade’s computers. They knew exactly what needed to be done, and the insertion was precisely the kind of well-specified problem that computers handled better than people, even Conjoined people.

Then it was over, and he was in. Not for the first time, Clavain felt a dizzying sense of vertigo as the comet’s interior space came into view. The husk had not stayed hollow for long. Its cored-out volume was filled with moving machinery: a great nested clockwork of rushing circles, resembling nothing so much as a fantastically complex armillary sphere.

He was looking at the military stronghold of his people: the Mother Nest.

There were five layers to the Mother Nest. The outer four were all engineered to simulate gravity, in half-gee increments. Each layer consisted of three rings of nearly equal diameter, the plane of each ring tilted by sixty degrees from its neighbour. There were two nodes where the three rings passed close to each other, and at each of these nodes the rings vanished into a hexagonal structure. The nodal structures functioned both as an interchange between rings and a means of guiding them. Each ring slid through sleeves in the nodal structures, constrained by frictionless magnetic fields. The rings themselves were dark bands studded with myriad tiny windows and the occasional larger illuminated space.

The outermost triplet of rings was ten kilometres across and simulated gravity at two gees. One kilometre of empty space inwards, a smaller triplet of rings spun within the outermost shell, simulating gravity at one and a half gees. One kilometre in from that was the one-gee ring triplet, consisting of by far the thickest and most densely populated set of rings, where the majority of the Conjoiners spent the bulk of their time. Nestling within that was the half-gee triplet, which in turn encased a transparent central sphere that did not rotate. That was the null-gee core, a pressurised bubble three kilometres wide stuffed with greenery, sunlamps and various microhabitat niches. It was where children played and elderly Conjoiners came to die. It was also where Felka spent most of her time.