Seveneves - Страница 118

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THE IRIS OF THE EYE WAS TOO BIG TO HAVE BEEN FABRICATED AS A single rigid object. It had been built, beginning about nine hundred years ago, out of links that had been joined together into a chain; the two ends of the chain then connected to form a loop. The method would have seemed familiar to Rhys Aitken, who had used something like it to construct Izzy’s T3 torus. For him, or anyone else versed in the technological history of Old Earth, an equally useful metaphor would have been that it was a train, 157 kilometers long, made of 720 giant cars, with the nose of the locomotive joined to the tail of the caboose so that it formed a circular construct 50 kilometers in diameter.

An even better analogy would have been to a roller coaster, since its purpose was to run loop-the-loops forever.

The “track” on which the “train” ran was a circular groove in the iron frame of the Eye, lined with the sensors and magnets needed to supply electrodynamic suspension, so that the whole thing could spin without actually touching the Eye’s stationary frame. This was an essential design requirement given that the Great Chain had to move with a velocity of about five hundred meters per second in order to supply Earth-normal gravity to its inhabitants.

Each of the links had approximately the footprint of a Manhattan city block on Old Earth. And their total number of 720 was loosely comparable to the number of such blocks that had once existed in the gridded part of Manhattan, depending on where you drew the boundaries — it was bigger than Midtown but smaller than Manhattan as a whole. Residents of the Great Chain were acutely aware of the comparison, to the point where they were mocked for having a “Manhattan complex” by residents of other habitats. They were forever freeze-framing Old Earth movies or zooming around in virtual-reality simulations of pre-Zero New York for clues as to how street and apartment living had worked in those days. They had taken as their patron saint Luisa, the eighth survivor on Cleft, a Manhattanite who had been too old to found her own race. Implicit in that was that the Great Chain — the GC, Chaintown, Chainhattan — was a place that people might move to when they wanted to separate themselves from the social environments of their home habitats, or indeed of their own races. Mixed-race people were more common there than anywhere else.

As in Manhattan, the discretization of the space imposed form on how it had developed, with each link of the chain — each city block — acquiring its own skyline and identity. Groups of consecutive blocks had long since coalesced into neighborhoods. Each block was, in effect, a fully independent space vehicle with its own system for keeping the air from leaking out. But each was connected to its two neighbors by a bundle of passageways routed through its foundation slab, which made it possible to move easily from one to the next in the same way that the Londoners of Old Earth had used underground passages—“subways” in the London sense of that word — to cut beneath crowded intersections. Some of the subways were sized for human pedestrians. Four of them carried trains: locals and express service running both directions around the full circuit of the Great Chain. Still others were reserved for robotic vehicles programmed to carry cargo. Beyond that was a wide range of smaller conduits carrying air, water, power, and information. All of them went by the name of subways — this was a conflation of the old London and New York senses of the word. At each end of each block was a system of airlocks; these would seal themselves off in the event that a block were to depressurize. People ran marathons through them — four consecutive marathons made up about one circuit around the entire Chain.

Every fifth link in the Chain was public property. These tended to be parks, though some served as cultural facilities. So you were never more than two links away from green, or at least open, space. The other 576 links were privately owned, and constituted a commercial and residential real estate market that would have been easily recognizable to any pre-Zero property magnate. The Great Chain had been likened more than once to the ancient board game of Monopoly. Some stretches of the loop were more high-rent, others less so. The pattern was interrupted in several places by special links, or short series of links, placed there to serve industrial and civic requirements, such as making the transit system work.

One of those was the Ramp Link, whose purpose was to make connections, every five minutes, with the On Ramp and the Off Ramp. Since the Great Chain was moving at about five hundred meters per second with respect to the nonrotating frame of the Eye, persons wishing to get from the latter to the former needed to be accelerated to a fairly spectacular velocity — almost Mach 1.5—before they could set foot on the Ramp, or any other, Link. And those wishing to dechain, as the expression had it, needed to be decelerated by the same amount. The acceleration and the deceleration were handled by machines built into a place on the rim of the “iris” of the Eye. Though some efforts had been made to camouflage their essential nature, they were really just guns for shooting humans, albeit humans strapped into comfortable, pressurized bullets.

Outside of the Great Chain, the rest of the Eye was lightly infested with human beings, heavily so with robots. Most of it existed in microgravity, since the entire contraption — Great Chain, tethers, and all — was in geosynchronous orbit, hence free fall, around Earth. As you moved away from its center, toward the two extremities of the Eye where the tethers emerged, you might begin to notice tidal forces, which would show up as very mild gravity-like tugs. These shifted whenever the Eye adjusted its orbit to move around the habitat ring, and people who spent a lot of time there could always feel in their bones when a move was under way, like Old Earthers predicting the weather in their knees.

The skeleton of the Eye was a simple space frame built in the Amalthean style, which was to say that it had been carved and shaped from existing material (Cleft) as opposed to fabricated from scratch. Aesthetically, it meant that the big structural elements had a rough-hewn, space-battered look about them, a bit like a log cabin with all the knots and bark still visible. Vacancies between the big structural elements had been filled in with giant machines, most notably several immense rotating masses whose purpose was to stabilize the whole Eye gyroscopically. The nooks and crannies between the machines had been caulked with pressurized spaces where humans could move about. Some of those rotated to produce simulated gravity; they were like miniature, torus-shaped space colonies pinned to a much bigger structure. Docking ports tended to cluster near those.

As Kath Two’s eyes closed into sleep, she was gazing at the usual ring-shaped formation of iridescent sparkles, so densely packed that they blended into each other on the varp. The Eye was a slightly larger white dot between twelve and one o’clock; it would have been difficult to see were it not for the long white line representing its tether system, which ran from just above Earth’s surface all the way through the big white dot and beyond to the Big Rock.

Their flivver’s trajectory, a sharp green ellipse, projected from where they were now (near Earth) all the way out to slightly beyond the ring before curving back in to intersect the Eye.

Through her eyelids she could see indistinct patterns, reminding her a little of the first thing she’d seen this morning: the flickering lights on the walls of her tent. But then the varp figured out that her eyes were closed and shut off the display.

When she opened her eyes, the varp noticed it and came back to life, rendering the display again. Generally it looked the same, but the Eye had moved a little bit, and the dot representing the flivver had covered most of the distance to the habitat ring. Zooming in, she could see the two habitats between which they were going to pass, and the much smaller rendering of the whip station between them, exercising its long hair-thin flagellum in preparation for their arrival. She must have slept for something like ten hours. Moirans were notorious for it. Remembering the looks she had exchanged earlier with Beled, she felt, then stifled, mild embarrassment over the fact that she had spent most of the journey snoring away.

She unstrapped and floated over to the zero-gee toilet at the end of the flivver’s cabin. When she emerged a few minutes later, she saw that Rhys was asleep, loosely strapped in before the control panel. Beled was still in his acceleration couch. He too had slipped on a varp, and she guessed from the way he was moving his hands and wiggling his fingers that he was working, as opposed to playing. He was probably filling out his Survey report. Which was what Kath Two ought to be doing.

They represented a civilization that had, during the Fourth Millennium, executed a plan to undo the damage caused by the Agent by identifying, cataloging, reaching, corralling, and revectoring millions of rocks in orbit around Earth, while also reaching as far as the Kuiper Belt to acquire chunks of frozen water and methane and ammonia and bring them home and smash them into the ruined planet. Essentially all of this work had been accomplished by robots. So much metal had gone into their construction that millions of humans now lived in space habitats whose steel hulls consisted entirely of melted down and reforged robot carcasses. It would have been easy for them to blanket the surface of New Earth with robots and, without ever sending down a single human being, perform a kind of survey: one that was heavy on data and light on judgment. In that version of the world, Kath Two and the others would have spent their lives in habitats, working at varps and mining data. All sorts of interesting philosophical arguments could have been framed as to whether that approach was better or worse than what they were in fact doing. But philosophy didn’t really enter into it. The decision to do it this way was driven partly by politics and partly by social mores.

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