Endurance
SEEN BY HUMAN EYES, THE HOLLOW HULK OF YMIR’S ICE SHARD WAS as dead, brittle, and gleaming as the discarded carapace of a beetle. Captured through the electronic eyes of cameras, then speeded up a hundred-thousandfold, so that the events of one day were compressed into one second of video, it looked like an amoeba pursuing, capturing, and swallowing Izzy. A person with no preconceptions of what they were watching would perceive Izzy as a steel-headed insect, all legs and pods and antennas, twitching and kicking in an effort to defend itself from the slow, relentless, liquid onslaught of the ice monster.
In truth, of course, the four hundred survivors, moving at lightning speed compared with the slow evolutions of the ice, were reconfiguring the space station in preparation for the Big Ride. The crippled Caboose was cut free and the components of the Shipyard moved forward. The big power reactor was brought in close to the Stack; from now on they would rely on ice to shield the rest of Izzy from its radiation. The eighty-one arklets arranged themselves into nine groups of nine and were tacked into place at the aft end, nozzles aimed backward. The structural works holding them into place at first were flimsy trellises on which spacewalkers could string cables, propellant lines, and hamster tubes. As soon as those were in place, the ice caught up with them, driven forward by the ceaseless operations of a giant Nat swarm, and the arklets were gradually cemented into place within a solid matrix of the fiber-reinforced ice known as pykrete.
Forward the ice flowed. It was like watching video of a melting iceberg played in reverse. The Nats, blindly following a simple collection of rules, packed it into every vacant space they happened upon. In the few minutes out of each day when the crew could take some rest and eat some rations, they would try to top each other telling funny stories about where they had found a living infestation of ice, and what they had done to beat it back.
Within a month, the remnants of Ymir had all been consumed, and Izzy had seemingly ceased to exist. The two of them had merged into an orbiting mountain. Its summit was a battered and scarified lump of nickel-iron, hazy with angular scaffolding where antennas and sensors were mounted. Its slopes were a smooth rampart of black ice, interrupted here and there by outcroppings of thrusters or other equipment, observation domes peeking out like hermits’ huts. Its base was a plane decorated with a neat grid of eighty-one small holes from which blue-white fire erupted from time to time as the ship passed through her perigee.
They couldn’t make out what to call the thing. People tried and failed to combine the words Izzy and Ymir. The closest they came was Izmir, but that had been the name of a city in Turkey. Sentiment was in favor of naming her after the martyrs of the Ymir expedition, but there had been several. In honor of Markus it was likened to the Daubenhorn, later shortened to the Horn. Which was not a bad nickname. But the name that stuck was a continuation of the Shackleton theme that Markus had established with New Caird. Shackleton’s big ship had been called Endurance, and was famous for having gotten stuck in the ice. So Endurance it was, and Fyodor christened her thus by getting into his battered Orlan, climbing out onto the surface of Amalthea, and dashing a bottle of champagne against the metal.
A more distant camera, looking down on Earth from high above the North Pole and watching the career of Endurance over the next years, would have seen a nail-biter of an opening, followed by endless grinding tedium, slowly building to a dramatic final reel.
Prior to Ymir’s arrival, the Cloud Ark’s pilots had put no small amount of attention into the problem of keeping Izzy out of the expanding atmosphere. This produced greater drag, which Amalthea, with its high ballistic coefficient, was well made to resist. But the decay of her orbit had to be mended from time to time with burns of the big engine that in those days had lived on the aft end of the Caboose, fueled by the Shipyard’s reactor-powered splitters.
The Break—as they called the event when the big bolide had smashed into Izzy, and the Swarm and Red Hope had gone their separate ways—had put an end to all that. Between then and the day about a month later when Endurance was christened, she spiraled gradually downward. Had the featherweight arklets tried to keep formation with her, they’d have been pushed back by the wind. They were forced to creep into the lee of Amalthea and ride along within her bow wave, like bicyclists slipstreaming behind a truck, until they could be integrated into the framework of the ship. Down and down she spiraled, and the SI team had to send Grabbs out onto the forward trusswork and remove the fragile antennas and sensors mounted there, lest they be slowly burned off by a rarefied but white-hot windblast. Fyodor’s champagne space walk was a brief one, and when he got back inside he reported that he could see the spraying foam of the champagne being blown backward by the atmosphere.
Their mission was to move their apogee from where it was now—just a few kilometers higher than the altitude of the perigee—all the way out to the altitude of Cleft, some 378,000 kilometers more distant. It was a reversal of the maneuvers that Markus, Dinah, Jiro, and Vyacheslav had executed in order to bring Ymir into orbital sync with Izzy. The way to achieve it was to burn the engines for brief intervals as Endurance made her regular swings through perigee.
The first of those burns happened about thirty minutes after she was christened, and yielded a delta vee of four meters per second. The acceleration was so mild that most of the crew could not even sense it. For the combined thrust of eighty-one arklet engines was nearly powerless against the bulk of Endurance, with her roughly equal masses of iron and ice. Nonetheless it was enough to boost her apogee, which occurred some forty-six minutes later, by 14.18 kilometers. And forty-six minutes after that, another burn during another scrape with the atmosphere gained them another four meters per second that, at the ensuing apogee, added 14.21 kilometers on top of that. The result of Endurance’s first day of operations was a boost in apogee altitude of more than one hundred kilometers, enough to get them clear of the expanded atmosphere except during the few minutes each orbit when they swung through perigee.
After that, however, they had to suspend operations, since they’d used up all the propellant stored in the Shipyard’s ice-buried tanks. They needed to give the reactor and the splitters some time to catch up. Even a nuclear power plant could split water only so fast.
Not long after, the operation was shut down for a week by problems in feeding clean water to the system. For another month it could only operate at about a quarter of its planned capacity. But over time they worked the bugs out and began to burn the engines more and more at each perigee, gradually extending Endurance’s reach toward Cleft.
If they could keep it up, that reach would get less gradual over time. The first delta vee had gained them 14.18 kilometers. The second, equivalent delta vee had reaped 14.21 kilometers—an improvement of about thirty meters. These gains were tiny in comparison to the distances of outer space, but from a mathematical standpoint the trend was extremely significant. It meant that the higher they went—the more elongated the orbit became—the more leverage they could obtain from each one of those tiny delta vees. That difference of thirty meters would grow and grow until it spanned many kilometers, and each of those improvements would feed back into the equations and amplify the next result a little bit more. It was an exponential sort of phenomenon, and this time humanity was on the right side of it.