Ice, of course, wasn’t the best material to work with. It was brittle. But the Ymir expedition had shipped out carrying a large supply of high-strength plastic cord, net, fabric, and loose fiber. And during the months that it had been coasting in from Grigg-Skjellerup, Larz’s robots had been at work converting ice into pykrete. That outer layer of visually black ice was no longer ice per se, but a synthetic material with much better structural properties. Frozen, it could stop bullets. Melted and strained, it would separate into water, artificial fibers, and black crud from the dawn of the solar system. In any case the larger robots—the Grabbs and the Siwis—responsible for doing most of the heavy material removal on the inside could scrape to within a few meters of that outer skin without compromising Ymir’s structure. It was the responsibility of the third Nat swarm to clean up after them and maintain the internal pillars and webs that would keep the reactor and the hoppers suspended in the middle of the hollow shard. This swarm-based ice-sculpting algorithm had been Larz’s invention, and he’d had a couple of years in which to perfect it, but Dinah was in charge of it now, and had a lot of learning to do between now and when she became fully responsible for it.
Outnumbered by the Nats, but responsible for moving a much larger tonnage of ice, were the hundred or so Grabbs and Siwis, now mostly stationed at the ready around the shard’s interior. Most of these were general-purpose robots with some added-on bits that made them good at moving on ice, but there were also half a dozen Leatherface machines: upsized Grabbs with shovel-studded chain saws for limbs, made to move a lot of ice in a hurry. These were so good at their jobs that they tended to destroy their surroundings, so they had to move frequently. Each one had to be followed around by an entourage of smaller robots cleaning up its mess and getting it anchored to fresh locations.
In theory it was all just a big computer program that, when executed, would smoothly convert the solid hill of ice into something like a walnut with the meat removed: a thick, pockmarked outer shell with an organic internal system of ribs, veins, and webs. As with any other computer program, it might run perfectly when Dinah started it. But it might just as well go sideways, perhaps in a manner that wasn’t obvious at first. So situational awareness was going to be a big part of her task. Interesting as it might be to look out the window and watch the Earth screaming by at twenty-four thousand miles per hour, she would need to keep her head down, searching through a roar of weak and ambiguous signals for signs that something was going awry. She liked to imagine that her days as a little girl in a mining camp, sitting in front of a radio console trying to pick out Morse code signals from far away, through static and crosstalk, might have prepared her for it in some way.
A FEW MINUTES INTO HIS SCAPE CONVERSATION WITH J.B.F., DOOB realized that, two years ago, he had done his job too well.
He’d gone into that meeting at Camp David with the mission of getting the president to understand the exponential breakup of the moon that was going to wipe out life on the Earth’s surface. Putting on his Doc Dubois hat, he had coined the terms White Sky and Hard Rain as easy-to-grasp handles on phenomena that, truth be told, were much more complicated. Dr. Harris was now wishing that the late Doc Dubois had never opened his big fat mouth.
He was in a corner of the Farm that, since the departure of New Caird, had developed into a sort of bullpen where he and Konrad and some of the other orbital mechanics geeks hung out. The Farm had always operated something like a high school cafeteria, with different cliques habitually sitting in certain areas, and now those choices were hardening, becoming a part of Izzy’s unwritten procedure manual. Anyway, they had printed out charts and plots representing, in more or less abstract form, everything that they knew about the ongoing development of the lunar debris cloud and what it might mean for the future of the Cloud Ark. The expenditure of paper and printer ink had been somewhat lavish. Two generations from now, if any humans survived, they would look on this heap of documents with some combination of disgust and amazement. Because paper was going to be scarce by then, and they would view its use for such purposes in roughly the same way as Americans of the twenty-first century had viewed the use of sperm whale oil to fuel streetlamps.
But then life would get better, forests of genetically engineered trees would grow in vast rotating space colonies, paper would become plentiful, and these sad yellowed scraps would be displayed in a museum as evidence of the privations suffered by the Arkers.