Seveneves - Страница 99

“WELL, THAT WAS HARD,” DOOB CROAKED, THEN WETTED HIS WHISTLE with a swig of the Ardbeg, mixed with a few drops of five-billion-year-old asteroid water.

He was in the Banana, speaking to an empty room, staring up at a projection screen on the wall. His reading glasses no longer worked; zero gravity had changed the shape of his eyeballs. The people who knew how to operate the lens-grinding machine were all dead or missing, so there was no way to make new eyeglasses until someone figured out where the machine had been squirreled away and read the instruction manual. Since only twenty-eight people remained alive on Endurance, this didn’t look like it would happen anytime soon. His distance vision was still pretty good, but because of the problem with the glasses he didn’t like to use his laptop for long periods of time. Instead he would come here to the Banana, soak up a little gravity, plug the computer into the projector cable, and work at long range.

He had been here for an hour, because he didn’t want to miss the big moment. He knew exactly when that moment would occur, plus or minus a few seconds, but in the meantime he couldn’t concentrate on anything else. The other twenty-seven were asleep or busy. So he was celebrating alone.

The display in front of him was dominated by a single large window displaying six numbers in fat, easy-to-read block letters. These were the orbital parameters of Endurance. They were updated several times a second, the numbers blurring and twitching. The one he was focusing on was labeled R, short for Radius. It was the distance separating Endurance from the center of Earth. At the moment, it was the highest it had ever been, at 384,512,933 meters and still climbing, slowly, in the last few digits. Endurance was creeping toward apogee, the highest apogee she had ever attained, and the height of that apogee was slightly beyond the distance at which the moon had once orbited Earth. For the first time they were as high in the sky, now, as Cleft.

Loose objects shifted position as Endurance’s remaining engines came on. They were down to thirty-seven functioning arklet engines from the original complement of eighty-one. On a good day they could muster thirty-nine. The other half of them had been cannibalized to keep the good ones working. To compensate for the losses, they had jury-rigged all the other engines they could get: the big one from the Caboose, all the propulsion units that had once been part of the Shipyard, and a few spare motors from straggler arklets that had become separated from the Swarm and found a way to rejoin them. Despite the reduction in engine power, Endurance was at least as maneuverable now as she had been at the beginning, when she had wallowed at the bottom of Earth’s gravity well, burdened with years’ worth of propellant. She weighed half as much now as she had in those days.

The burn went on for a while. It concluded with a change in attitude and a burn in another direction. Doob didn’t have to read the numbers on the screen to know what they were doing. They’d been planning it for three years.

They were in a highly eccentric orbit now, a pair of hairpin turns welded together by straightaways a third of a million kilometers long. Earth nestled deep in the crook of one of those hairpins. Endurance’s perigee hadn’t changed in three years; on every one of the thousands of orbits they had made, they had screamed across the top of Earth’s atmosphere while running their engines full blast. On the last such pass, which they’d made about five days ago, they’d topped out at more than eleven thousand meters per second of velocity. The visual symmetry of the orbit was deceptive; at their current location, the opposite hairpin, now slightly beyond the old moon’s orbit, they were crawling along at a speed that could have been matched, back in the day, by a wheeled vehicle on a salt flat. They were like a car on a roller coaster that had been towed all the way to the top and that was creeping along in that moment before it begins the plunge down to the bottom. The Earth was the size of a ping-pong ball at arm’s length. Soon they’d begin falling toward it, building back up toward eleven thousand meters per second during their next perigee pass, five days from now.

In the meantime, though, during these few minutes when they were just inching along, they could work magic. Small changes in velocity out here led to enormous transformations in their orbit down there. Endurance, by dint of enduring for three years and persevering in her plan, had reached Cleft’s distance from Earth. But she’d always been in the wrong plane: the same plane that Izzy had started out in, the plane that had been chosen, seemingly a million years ago, because it was easily reached from the Baikonur Cosmodrome. Down there, deep in the gravity well, changing that plane would have been catastrophically expensive. If they’d had an Earth to go back to, it would have been cheaper to start from scratch and build a new space station than to move Izzy to the plane where the moon had once orbited. Up here, though, by burning the engines at apogee, they could nudge it closer and closer to the desired plane at much lower cost. So they’d been doing little plane change maneuvers at each apogee. It had been going on for months now. It was a thing that had to happen if they were ever to reach Cleft, but it made Doob’s stomach burn, made him wish he hadn’t had a couple of slugs of hoarded single-malt.

For the plane of the old moon — the place they had to go to find safe refuge in Cleft — was where all the rocks were. That was where the rocks had started out, at Zero, and for the most part that was where they had stayed. The ones that had fallen to Earth in the Hard Rain were only a tiny fraction of the lunar debris cloud: just a faint dusting compared to what remained up here. During most of Endurance’s journey, her pilots had, by choice, kept her in that angled Baikonur-compatible plane, well clear of the moon’s debris field. Otherwise they could never have survived for this long.

But the risk that they had to accept, in order to try for Cleft, was to fly through the debris cloud in which Cleft swam. Every time they had reached an apogee in the last few months, and burned their engines to bring their orbit closer to the plane of their destination, they had edged into dirtier and more dangerous space.

Their slowness was part of the problem. If the debris cloud was a fleet of cars roaring around a circular raceway at top speed, then Endurance was a child toddling out into traffic. That extreme disparity in speed would remain until the next apogee, ten days from now, when they would make their biggest and longest burn, expending all of Endurance’s remaining propellant to accelerate her to the same average speed as the debris cloud. In so doing, they’d convert the dual-hairpin orbit into a nearly perfect circle, remaining 384,512,933 meters from Earth forever. Having merged smoothly with the traffic on the circular raceway, they would go hunting for Cleft. Doob had spied it several times on his optical telescopes, gotten a fix on its params, knew how to find it.

This was his life’s work.

If he’d been asked several years ago, before Zero, he’d have said it was something else. But his life until Day 360 had been nothing more than preparation for the mission plan he had laid in and was now executing for Endurance. The day of the Break — the arrival of the propellant needed, the death of his friend and colleague Konrad, and the sundering of the Swarm — had made it clear what needed to be done, and who needed to do it. So he’d been doing it.

Ten days remained until they were swimming in the debris cloud. Perhaps a fortnight before they reached Cleft. He wondered if he would live to see it. Quite obviously, he had cancer. Diagnostic facilities were lacking, but the first undeniable symptoms had been in his digestive tract, and since then his liver had become swollen by metastases. Now he was feeling some weird stuff in his lungs. It had grown slowly. It might have been natural causes — something that had been seeded on Old Earth, before he had even come to space — or it might have been a piece of fallout that had made its way into his food and gotten caught in his gut. No matter. The main question on his mind was whether he would live to see Cleft. He actually didn’t feel that bad, and so the naive answer would be yes, of course; but cancer growth was something of an exponential phenomenon, and he knew how tricky those could be.

Bolor-Erdene was flying the ship, working in the Hammerhead — the deeply sheltered control room that they had built into the lee side of Amalthea. Or at least she was on the duty roster as the nominal pilot. Distinctions of rank and specialty had ceased to matter much. Everyone who had survived — nine men and nineteen women — knew how to do everything: fly the ship, fix an arklet engine, go on a space walk, program a robot. The Doob of a few years ago would have ridden it out in the Hammerhead with her, looking over her shoulder, checking the params, swapping witty remarks in the occasional moment of downtime. The Doob sitting in the Banana right now had seen it all before, thousands of times, and knew that it was as routine to Bo, or to any of the survivors, as driving to work would have been before Zero. Being there would only have gotten his stomach riled up. He needed to conserve his energy.

He realized that he had dozed off. Opening his eyes and focusing, with some effort, on the screen, he saw that nearly an hour had passed since apogee. They were falling toward Earth for the last time.