Pushing Ice

by Alastair Reynolds

  “How long do you need?”

  “Two years, give or take. It’ll involve a lot of cargo flights, a lot of people down here.”

  “Two years is too long,” Svetlana said. “Any chance we could halve that?”

  “Halve it?” Ramos said incredulously. “Well, that might take some doing.”

  “I want you to put together a plan for gearing this thing up within twelve months. I’ll give you all the fuel you need, all the robots, and twelve people — that’s the most we can possibly spare from topside.”

  “Well…” Ramos hesitated, understandably fearful of committing to something she was not certain she could deliver. “I’m not even sure we have enough superconducting cable to reach down here.”

  “We’ll have the forge vat online within six months. Priority one will be spinning out new cable.”

  “Once you’ve dealt with all the other things on the list,” Ramos countered, unconvinced.

  “We need this,” Svetlana said forcefully. “Sooner rather than later.”

  “But the fuel crisis — that’s still a long way off, isn’t it?”

  “Yes,” Svetlana said quickly, trying to strike the right note of soothing reassurance, “but all the same — better safe than sorry, right?”

  “We’ll do what we can,” Ramos said.

  FOURTEEN

  A sea of black ice flowed under the lander as it traversed the shelf. Parry dozed again, his head lolling against the window. Svetlana followed his lead and power-napped for ten dreamless minutes. When she came to, the lander was on final approach for Crabtree, Ungless making the same unforgiving economies with fuel. Svetlana thought about the easy promises she had given Ramos: all the fuel and machines she needed, and twelve strong workers. As if it was ever going to be that easy.

  Lesson one on Janus: nothing was easy. The lander made a descending curve around the central tower that had once been Rockhopper. Nine hundred metres of the ship projected above the foundation well Parry and his team had punched into the Janus ice. They had buried the ship stern-down, with the engine, reactor assembly and fuel tanks completely underground. Just like plugging a mass driver into a comet, Denise Nadis had said. All that was visible now was the spine and the top-heavy bulge of the habitat section. Tether lines splayed out from the hab in four directions, anchored to the ice with sprayrock-embedded pitons beyond the loose perimeter of the surface community.

  The ship was never going anywhere again. No one even thought of it as a ship any more. Rockhopper was just the central tower of Crabtree: its administrative core and power station. It was a resource to be stripped and remade for the good of the community.

  Of the hundred and forty-one people on Janus, most now chose to dwell outside Rockhopper. Thirty domes spread away from the base of the ship, linked by underground tunnels and pressurised surface corridors. Ice had been lathered up over the sides of the domes to provide additional insulation, lending them the look of half-melted igloos. Most of the domes were just large enough for a single family-sized unit: three or four people at most.

  The domes closest to the ship had been put down first: Parry’s EVA team had used them during the initial cometary operations. Those further out were improvised structures, lashed together using metals and composites scavenged from Rockhopper, with offcuts of parasol foil providing the basic pressure-containing envelope. Sprayrock was a quicker building medium, but like everything else it had to be used sparingly now. Between the domes lurked equipment modules, generators and storage shacks. A scattering of pale-yellow window lights hinted at human presence. Blackouts were enforced during long hours of each day. Svetlana would gladly have extended the duration of the power outages, but she was concerned about spreading panic.

  The lander bumped to ground beyond the edge of Crabtree.

  They disembarked and boarded a wire-wheeled tractor that had been waiting at the edge of the apron. Ungless took the tractor’s controls and drove it along a furrowed, slipshod road that cut between the tents and their snaking connections. Crabtree was still only a hamlet, but at times it felt as if it was poised to become something larger. If the deaths slowed and the births continued, then within ten years, by the time they arrived at Spica… But Svetlana closed the book on those thoughts. She did not hold out any hope that Janus could be slowed, let alone reversed, but unless their current fortunes improved, they could not count on surviving until they reached Spica either.

  She kept having to remind herself that it was not October 2059. It was… some other date that she did not want to think about. 2059 was just a lie they told themselves to stay sane, to comfort themselves that they had not already drifted too far upstream ever to return home.

  It was the one piece of advice Svetlana had accepted from her, before the exile. Honour the old calendar: make a day count as a day, even as their increasing speed squeezed time until it bled.

  Two months after Rockhopper‘s entry into the Janus slipstream, the moon had reached a speed that was slower than light by only one-tenth of one per cent. Janus had stopped accelerating once it reached that speed, but it was still harrowingly fast. Relativity dictated that clocks ran twenty-two times slower on Janus than they did on Earth. Not just clocks, either, but every measurable physical and biological process. Including time itself.

  In the hour that had passed since she had said goodbye to Ramos, nearly a full day had elapsed on Earth.

  Janus had been at cruise speed for twenty-two months, as measured by Rockhopper time. On Earth, forty years had passed. It was somewhere near the closing years of the twenty-first century. If by some unlikely good fortune they were to succeed in turning around now, eighty years would have elapsed by the time they made it back home.

  It would be nearly 2137.

  Not everyone accepted this. With its antennae pointed back home, Crabtree was still intercepting radio signals originating from Earth. The messages were red-shifted towards ultra-long wavelengths, but information could still be gleaned from them. And according to the messages it was still only 2059. They heard news from families, loved ones, friends — but a little less with each week that passed.

  The world they’d left behind spun on, half-familiar news stories still dominating the headlines. The same celebrities, the same scandals and tragedies. For a little while the plight of Rockhopper and its crew had even been one of those objects of global attention, until something quietly displaced it and they faded into the back pages. The messages were dangerous and comforting in equal measure. They told a lie, but only because they were bound to the same universal speed limit as Janus. Messages from 2097, or even 2137, would not catch up with Janus before it reached Spica. They would never learn the history of the world they had left behind.

  Not until they turned for home — at which point they’d be flying headlong into that blizzard of information. The years would crash forward: eighty years of history crammed into the two years of their return flight even if they succeeded in turning around now. And if they did not begin their return journey until after Janus reached Spica, they would have to recapitulate five hundred and twenty years of history.

  That was too much to take in, so they used the old calendar and pretended that every day that passed on Janus had the same measure as a day on Earth. It gave their lives some structure. They celebrated birthdays, holidays and festivals. They still talked of summer and winter, and made some effort to mark these seasonal changes in the way that the blackouts and brownouts were imposed on Crabtree’s electrical supply. Svetlana had done all that she could to make the last summer a little better, a little more tolerable, than the grim winter that had preceded it.

  But now it was winter again and the fuel tanks were running perilously low.

  Above the settlement, a huddle of blood-red stars crowded the zenith directly over Crabtree’s central tower. There were no stars at all anywhere else in the visible hemisphere of sky: they had been torn from their fixed positions by the iron hand of relativity. Most stars were red to b
egin with, so the Doppler effect only made them redder. On the bow side of Janus there was another, brighter huddle, where starlight had been shifted ferociously into the blue. It was as beautiful as it was lethal. Bracelet dosages went through the roof as blue-shifted cosmic rays sliced flesh and cell.

  The electric tractor bumbled down an ice-walled ramp into one of the equipment bays dug out around the base of the downed ship. They disembarked, passed through another airlock and were helped out of their suits by a beaming Kunj Ramasesha. Like Ramos, Ramasesha had made the transition to Janus life with relatively little difficulty. The suit technicians — not just Ramasesha, but Ash Murray and Reka Bettendorf — were vital to the functioning of the new colony, and they revelled in their new sense of civic importance, guarding their expertise with the zealotry of a medieval guild.

  Svetlana and Parry bade farewell to Ungless and rode a car up the spine to the hab. Although the Janus machinery gave off its own glow, none of it reached Crabtree. The ice around the little community was as dark as space, lent only the faintest midnight sheen by the cluster of red-shifted stars in the stern hemisphere. A few transponders winked out of the darkness like distant lighthouse beacons. As the car rose higher, Crabtree looked like the only human artefact in the universe.

  Svetlana had timed her return well: she was only a minute late for the meeting with the other members of the Interim Authority. They had assembled in what had once been the captain’s office and private quarters. The cramped old room was twice as large now: internal partitions had been torn down throughout Rockhopper, the material used elsewhere. The old carpet no longer met the walls, but it remained the focus of the room. Even the fish tank was still there, and there were even some fish in it. Some parts of the old ship were routinely spun to provide centrifugal gravity — Axford insisted on having such a facility since calcium loss was a real concern under the weak pull of Janus — but this was not one of them. The fish did not appear to mind too much.

  Ryan Axford was present, along with Saul Regis, Nick Thale, Denise Nadis, Jake Gomberg and Christine Ofria. Like Axford, Regis and Thale had both been old-regime loyalists, but their expertise was too essential to ignore. Sometimes there was tension between the three of them and the rest of the Authority, but they were usually pragmatic enough to put such things aside if it helped Crabtree.

  Svetlana and Parry took their places around the table, moving with the effortless glides that characterised locomotion on Janus. Svetlana lowered herself into her seat, folded her hands on the table before her and nodded briefly at the other members.

  “I’ve just returned from the Maw,” she began, “and for once it looks as if we might have discovered something that could almost be described as good news. To put that into the proper context, though, I must emphasize how truly shitty things really are. Parry: will you do the honours?”

  Parry removed his cap and scratched a finger into his moustache. “I won’t even attempt to put a positive spin on any of this, and I’m sure it’ll come as no surprise to any of you that fuel is our main problem. Before we landed on Janus, we had high expectations of tapping the moon’s energy for our own uses. That was a nice idea, but it hasn’t turned out to be so simple in practice. The Spican machinery is hellishly efficient: it doesn’t give off a lot of waste energy for us to exploit. The only area where we’ve had much luck is with the thermoelectric generators — they exploit the heat difference between the Spican machinery and the icecap. But the heat difference isn’t huge, and we don’t have enough superconducting cable to run any more lines out to the edge of the icecap. If we were going back to square one now, we might choose a different landing site, closer to the shelf… but since we don’t have a time machine —”

  Nadis tapped a stylus against her flexy. “How much power are we getting now?”

  “From the thermocouples? Depending on fluctuations in the machinery, anything between three to five megawatts, which isn’t enough to run Crabtree. We’re fine at the moment because we can still run the fusion engine — we’re easily extracting a hundred megawatts. But it isn’t efficient: Lockheed-Krunichey built that engine to move Rockhopper around, not light up a village. We waste far more energy than we extract.”

  “The fuel won’t last more than fourteen months,” Svetlana said bluntly. “Eighteen if we eke it out with even more power outages and shut down some of the outlying domes.”

  “We might as well stop rationing the coffee, in that case,” Nadis said.

  “There’s no hope of squeezing more power from the thermocouples?” Thale asked.

  “Even if we get the forge vat running and scrape together the raw materials and power to spin out more superconducting line, we’d only be looking at doubling our capacity from the thermocouples,” Svetlana said, “which won’t even get us through to next summer. We’d still be relying on the fusion engine.” Parry cleared his throat. “We’ve been looking at other options. Heat isn’t the only thing Janus has to offer us. As most of you probably know, we’ve had a team looking into the possibility of extracting power from the lava lines — either directly, or by tapping the motion of the transits. So far we’ve had no success, but it is a possibility for the future. We just have to stick around long enough to get there.”

  “Hence this meeting,” Svetlana said. “Two weeks ago, we learned something significant about one of the structures in the Maw chamber: it’s rotating. It’s slow — almost too slow to notice — but it’s regular and it appears to have immeasurably high torque. If we can tap that motion, there is every chance that we’ll be able to turn off the fusion reactor and save the remaining fuel for the day when we really need it.”

  Svetlana let the little party absorb that glimmer of good news. It was all they were going to get from her. “Okay,” she said after a few moments, “now for the hard part: actually doing it, and doing it before we all die anyway. It isn’t going to be easy, but we think we have a roadmap.”

  “There are two difficult parts to this operation,” Parry said. “The first is tapping that rotational motion and converting it into electrical power. The second is getting that power out of the Maw and back to Crabtree. The first part is where most of the headaches are going to arise. Problem number one is that the spire — the rotating structure — is turning very, very slowly. But we think we can deal with that.”

  Svetlana called up a diagram on their flexy and projected it onto the wall behind her. She leaned back in her seat, twisting her neck to take it all in. It was a crudely drawn sketch of the spire in the Maw chamber, with something approximating a set of gear teeth fixed around its base.

  “We’ll begin by attaching cogs all around the structure,” she said. “They’re basically just chunks of machined metal. We know glue works, and we know what kind of torques the adhesive bonds can tolerate before they fail. Ramos and the others say it can be done. That gives us a system for coupling a second, smaller wheel to the spire’s rotation. That wheel will turn faster.”

  “But still not fast enough,” Parry said. “We’re going to have to lash up loads of these things: a clockwork gear train like nothing you’ve seen since the sixteenth century. We’re going to need a gear ratio up in the millions.” There were exasperated sounds, but Parry pushed on. “We’ll strip out one of Rockhopper’s main centrifuge rings and the associated drive system: that should give us the building blocks, or at least enough to make a start. Whatever we come up with, it’ll have to work flawlessly. And at the end of it we’ll need an output shaft turning at around one hundred hertz.”

  “To which we can couple as many industrial-capacity dynamos as we can put our hands on,” Svetlana said.

  “I expect there are some lying around here somewhere,” Nick Thale said, his voice dripping sarcasm.

  “There are,” Parry said firmly. “We used them every time we pushed ice.”

  Thale’s eyes narrowed. “Mass drivers? I don’t see how linear —”

  “The parasol spinners,” said Nadis, nodding appreciativ
ely. For the apparent benefit of Thale and Regis, she added, “The electric motors we use to spin up the sunshade parasols, to shield the dayside of the comet during the infall cruise.”

  “That’s the idea,” Svetlana said, nodding approvingly. “We reverse them, use them as dynamos instead of motors. We’ll have to beef up some of the components, but I’m told it’s workable. If we can solve the drive-shaft problem, we can tap fifteen to twenty megawatts. That’ll free us from any further dependency on Rockhopper’s fuel — but only if we can convey that power to Crabtree. For that, we’ll need about four times our current mileage of superconducting cable.”

  “Then it’s hopeless,” Nadis said, exasperated. “We can’t even fix the existing cables, let alone make more of them.”

  “Not yet,” Svetlana said, “but if we can get the forge vat running, we can spin out all the cable we’ll ever need.”

  “Have you spoken to Wang lately?”

  Svetlana did not care for the tone of the other woman’s voice. “Not for a few weeks,” she said defensively. “The last I heard, he was making good progress.”

  “Maybe you should visit him one of these days,” Nadis said. “I think you’ll find it illuminating.”

  “I will,” Svetlana said, annoyed with herself for not having kept a closer watch on Wang’s stumbling progress. “As soon as we’re done here. Assuming we can get the vat up to speed, I take it everything I’ve proposed here has the committee’s approval?”

  “It’s not as if we have much choice,” Parry said. “If we don’t tap Janus, we’re finished within a year and a half.”

  “I agree that it looks clear cut,” Thale said, “but let’s not underestimate the risks. So far we’ve barely scratched Janus. Sometimes I wonder if it’s even noticed us yet. But if we start interfering in more obvious ways —”

  “We have no choice,” Svetlana said.

  “I’m just saying — there may be consequences.” Thale looked at the others, inviting support. “We shouldn’t kid ourselves that this is a risk-free strategy.”