3
The call came in to Will Davis's suit. He at once turned to John Hyslop, just a few feet away from him. "This is for you, boyo."
"Cusp Station local? If it is, it can wait until we're finished."
"Not this one. Urgent, from Sky City. They called me because they say your suit doesn't answer."
"Of course it doesn't. I switched off so we could get some work done. But I can't ignore it if it's Sky City and urgent. Damnation. What do they say?"
"I don't know. It's personal, and it's scrambled. We can't go direct link. I'll have to relay through Cusp Station control to your suit, so you can decode."
It seemed ridiculous. The two men floated side by side, less than four feet from each other. They could have put their helmets together and talked without any radio link at all, but a scrambled message could not be transferred and interpreted that way. Also, from John Hyslop's point of view the communication could hardly have come at a worse time. Sky City maintained mid-Atlantic, a clock zone convenient for workdays in America and Europe. So far as city workers were concerned, the call to John was made at eight in the morning—a reasonable time.
But the few humans and innumerable machines working on the space shield enjoyed no regular hours and no fixed clock. Schedules were defined by need, with always the same underlying message: Do this as fast as you can, and remember that it may not be fast enough.
The cat-sized rolfes, robotic brainchildren of Gordy Rolfe and his great contribution to the building of the space shield, could work twenty-four hours a day. But humans could not. So the call arrived when John Hyslop, Amanda Corrigan, Will Davis, Lauren Stansfield, Rico Ruggiero, and Jessie Kahn were at the tail end of a thirty-hour troubleshooting stint. John and Lauren were also at the tail end of their stamina. They had been up for seven hours before this effort began, tying up a meeting at Sky City before heading for Cusp Station. For the final ten work hours their awareness had been Neirling-boosted, so they would have to boost again soon, or crash. And when you crashed, you stayed out for a full sleep period. John had hoped to see this meeting to its end, then fade at once.
He switched to internal mode and listened to the message as it was unscrambled by his suit. "Dr. Colombo needs your presence as soon as possible on Sky City. We have a new problem."
The voice was that of Goldy Jensen, Bruno Colombo's personal assistant. Her tone—like her message—revealed nothing more with repeated hearings.
A new problem.
That might, please God, mean a technical difficulty. The John Hyslop job description, if anyone ever bothered to pull it up and read it, said he was chief engineer for the shield. In practice, he seemed to do whatever Bruno Colombo needed him to do, on Sky City and off it.
John switched back to external mode. Will Davis and Lauren Stansfield were uploading the proposed revision for the construction profile of one section of the space shield into the subsidiary computation network at Cusp Station while Jessie, Rico, and Amanda transferred the group recommendations to Torrance Harbish and the main network back on Sky City, where the real computing power resided. But they all had one eye on him. As soon as he clicked back to local circuits they stared at him expectantly.
"Everything all right?" Lauren asked. She was John's number one assistant, a short, soft-spoken woman with auburn hair and big eyes. She dressed well and expensively, which together with her careful attention to her appearance made some of the engineers regard her as a lightweight. John knew better. He had learned to rely on Lauren in any emergency. She knew more about the interior layout of Sky City than anyone—John included—and her only hobby seemed to be roaming the space city's thousands of corridors, checking the various life-support systems.
Now she was asking a question within a question. They had two more decisions to make before the meeting ended, and Lauren wanted to know if that would be possible.
There was no point in waiting, and no way to pull out gracefully.
"I'm sorry." John spoke on open circuit. "Everything here is going well, and I think we're pulling things back toward schedule. But I have to leave. I must return to Sky City."
Jessie Kahn was young, new, naturally shy, and up from Earth only four months. She also had an intensity and an honesty that outweighed her natural reticence and, in John Hyslop's view, pointed to a very bright future.
She said at once, "The questions of reduced shield efficiency and probable sensor losses must be addressed today. They can't wait. And those issues require your personal involvement and approval."
"I know." John realized that he was going to shock her, but she had to learn sometime about the world of impossible deadlines. "I'll fly back. You get in touch with me when your meeting finishes. Whatever you decide, I'll approve it."
He saw her face. He was feeling the pressure himself, and he was tempted to add, Don't give me a hard time, Jessie. I'd hate to spoil your idealism, but I don't have time for polite discussion. I have to boost again, because when I reach Sky City I have to be awake for whatever shit Bruno Colombo throws at me. And the thought of that second boost doesn't thrill me at all.
His warning wasn't necessary. Will Davis was a seasoned shield engineer who had spent only three days on Sky City in the past year—the opposite of Amanda, Lauren, and Rico, who left Sky City only when dragged out for emergency efforts like today's. But Will was Jessie Kahn's unofficial mentor, and he knew enough to step in and ask in his lilting Welsh, "What is it then, John Hyslop? A direct command? Might it be you've received marching orders from His Lordship?"
"You've got it."
"What's he want with you this time?"
"Do you think he's going to tell me before I get there?"
"No, man. Not if he's half the pain in the ass he used to be. I'm glad it's you off to see him and not me."
Everyone but Jessie laughed. They had suffered their own unpleasant experiences with Bruno Colombo. She, not sure how the conversation had suddenly veered away from her concerns, looked from one person to the other but said nothing.
John decided that there was no point in further discussion. The others could give whatever additional explanations they liked. "I'm going to do a second boost, Lauren," he said. "Right now. You don't need to do that, so make sure you get somewhere safe before you crash. Will, you'll have to wrap it up here in an hour or two. Make sure the rolfes are reassigned to the shield when you're done with them."
Their meeting was taking place in hard vacuum. John headed straight for the station exit, switched to suit channel as soon as he was outside, and said, "Take me to Sky City. Use a continuous one-gee thrust trajectory, and provide a zero relative velocity on arrival."
It was a routine command. The return trip along the extended spine of the space shield and the transfer trajectory to Sky City would require none of John's attention. His personal suit informed him that a one-gee boost with midpoint turnover would carry him the hundred-thousand-plus kilometers from Cusp Station, at the outermost limit of the shield, to his usual docking port on Sky City in one hundred and sixteen minutes.
One hundred and sixteen minutes, in extended boost mode and with little to do but indulge in worried speculation. Couldn't Bruno Colombo have offered a word or two to indicate the nature of the difficulty? Something like, they had a different problem and not just another problem? Or had there been another death, another disappearance, another frightful episode in a lengthening sequence?
Probably not. But the murders were getting to him, as they were to everyone living on Sky City.
The suit was accelerating him smoothly along the axis of the space shield. The shield was eighty-five percent complete, but for that you had to take the word of the computers. There was nothing to be seen.
John looked out to the side anyway, at right angles to his direction of motion. Of course, he saw nothing. The three-billion-ton mass of the shield was there, but it spread out to form a narrow cone almost a hundred thousand kilometers long and eighteen thousand kilometers across at the base. The matter in the shield, about a gram of it per square meter, formed a delicate spiderweb of superconducting fibers, load filaments, node sensors, thrustors, and computing tubules. It could stand considerable tension forces, but an ounce of compression anywhere would make it buckle. The structure made small but constant adjustments in relative geometry and overall position to prevent that. The computational problem was continuous and complex. The shield had to maintain a fixed shape and position in the presence of time-varying forces: Earth attraction, lunar, solar, and planetary perturbations; solar wind and radiation pressure. And, of course, it must deal with the variable but steadily increasing sleet of charged particles that provided the shield's whole reason for existing.
John looked down past his feet. For reasons of personal comfort, suits usually accelerated you headfirst. Until turnover time that meant Cusp Station lay directly below him, at the apex of the cone, while Sky City was above his head.
Sky City, which for the past seven months had been prowled by an insane—
No. Not that. Those thoughts were the effects of the second Neirling boost on his nervous system. He had to get his attention fixed on something tangible.
Cusp Station was still visible below, a bright cluster of green and orange lights. No word from Will and the others. Presumably they were still chewing on the technical problems.
But Cusp Station was not what he wanted to see. He added an apodizing disk to the suit's optical sensor, removing the unwanted glare of the station, and scanned the area close to it. After a few seconds he located his target and locked on.
And there it was. An undistinguished second-magnitude star, one of hundreds of that brightness in the sky. Yet a star like no other.
For all of recorded history Alpha Centauri had been the third brightest star in the heavens: Rigel Kentaurus, a splendid visual binary with a third and faint companion, Proxima Centauri.
Thirty-one years ago, the Alpha Centauri system had exploded as a mighty supernova. But because Alpha Centauri was about four and a third light-years from the Sun, no one on Earth knew what had happened until twenty-seven years ago, when early in 2026 a torrent of light reached the solar system. For several months Alpha Centauri blazed down on Earth like a second Sun.
The cascade of light had created freak weather and global devastation. The flux of high-energy gamma rays, a few weeks later, knocked out all microcircuits and everything that depended on them. Civilization shuddered, gasped, staggered—and thought it had survived.
Until it realized that the Alpha Centauri supernova, unpredicted by all scientists and proclaimed impossible by most, had not finished with the Earth. The star had waned, until the faint remnant provided a poor object for visual observation. But most of the energy of a supernova is not given off as light or gamma rays. It resides in the sleet of electrically charged subatomic particles thrown out during the stellar explosion. That particle storm, fast-moving as it is, travels much more slowly than light. In the case of Alpha Centauri, the densest cloud was calculated to move at about nine percent of light speed. Travel time from Alpha Centauri: about forty-eight years. Arrival date for the storm center: forty-four years after the first blaze. Say, in 2070.
Earth would need protection. But there were further complications, introduced by the particle velocity distribution. To find when a particle storm has its biggest effect, you must look not at simple particle density but at the product of particle flux density and particle kinetic energy. The most energetic and destructive particles are the ones that travel fastest. Hence the worst time would be earlier than 2070. It was predicted as 2061.
No. The worst time is here and now, with murder most foul on Sky City . . .
The suit's acceleration ended abruptly. The skyscape swirled dizzily, bringing John shuddering back to reality.
Turnover time. Halfway to Sky City. Still an hour to go. An awful situation. The Neirling boost was designed for when you were desperately busy with more work than you could handle. Employ it when you had nothing to do, you were like a motor running against zero load. Your brain spun faster and faster until it burned out its bearings. And in this case John knew exactly where his brain would run until it blew: on the subject that he was trying to keep out of his mind, the awful deaths.
He had to find something to do.
He transmitted to Cusp Station. "Will? It's been an hour and I've not heard a word from you. What's going on?"
It was a few seconds before he heard a reply. The delay wasn't travel time; that was negligible over such a short distance. He must be interrupting something.
"We've been solving problems, what do you think?" Will Davis's voice held a touch of surprise and perhaps reproach. "Not like some people. We're done with what we were working on when you left, it's on the way to your office for you to approve. Lauren's down and out; she crashed a few minutes ago. What's wrong, John? Feeling lonely?"
"Not lonely. Insane would be better. I had to give myself that second boost, otherwise I'd be sleeping when I get to Headquarters. But now I'm going crazy out here with only the stars for company. I need something to do. Link me in for your visuals, will you?"
"I could, but you won't get much from seeing me and the others just sitting here. I can give you something a lot better to chew on. It's what we're stewing on ourselves, when we'd all be better off sleeping. Yesterday the deep space network received a new Sniffer profile, and nobody likes the looks of it. The flux profile for uncharged particles from Alpha Centauri has changed. Increased."
"Bad news." John didn't need to say more. The electromagnetic field created by the finished shield would change the trajectory of charged particles. They would be diverted, passing around Earth and leaving it untouched. But neutral, uncharged particles were not affected by the field. They would get through and smash into the shield. Too much of that, and the fragile barrier would be destroyed. Then everything would get through, charged and uncharged, to hit an unprotected Earth.
"Also, we just received a new simulation," Will went on. "It came in from the analysis team back on Earth after you left. We assume that they incorporated the new Sniffer data, though it's hard to see how they could have done it so fast. Either way, they've worked out what will happen from now to the time of maximum particle flux if we don't make changes to the construction schedule. Remember the protocol for changing display time rates?"
"I do."
"Then here goes. Standard color codes."
John's personal suit switched to remote visual mode. The real external world remained visible as a faint superimposed star field. Fatalities early in the construction of Sky City had led to a decision that the immediate environment must never be completely excluded in favor of remote image data.
The simulation employed a standard vantage point for shield display, a position in space a million kilometers from Earth and fixed in the plane of the ecliptic. The planet sat at the middle of the field of view, a blue sphere almost twice the size of the full Moon as seen from Earth. The space shield formed a long, narrow cone, slightly flared at the end like a trumpet. Invisible to human eyes, it had been stylized in the simulation to show as a web of light blue against a black background. The cone was widest closest to Earth, with the central axis pointed directly away from the planet at about forty-five degrees to the ecliptic. In that direction lay Alpha Centauri, impossibly remote yet dictating every human priority.
The effectiveness of the shield at a given time depended on the balance of two factors: the shield's stage of completion, and the energy and composition of incident particle flux. "Hot spots," locations where the shield was inadequate to redirect the charged particles, were delineated in vivid hot pink. Trouble locations where the situation was improving sat as green islands within the hot spots. Places where things were getting worse showed as stigmata of flaring orange.
The default time rate for the simulation was forty-two thousand to one. At that setting the Moon provided the observer with a natural feel for the pulse of events. Once a minute the sunlit white marble made its four-hundred-thousand-kilometer sweep around Earth, oscillating four or five degrees above and below the plane of the ecliptic.
At that rate, the display of the period from the present to the time of maximum flux energy would take a hundred minutes; long before that John would be at Sky City. He called for a tripling of simulation display rate and settled back to watch. Already he was having premonitions. Will Davis would never suggest such a viewing unless the implications were severe.
In any case, John would have caught the problem even without prior warning. He remembered the results of the simulation from four months ago. Superimposed on the blue web you would always see a scattering of pink patches, within which the flecks of green and orange came and went apparently at random.
Today was different. Eight minutes into the display— less than two years ahead in real time—the pattern began to change. Pink patches spread. Within them he saw few flecks of green. The orange glow of worsening problems dominated.
Something had changed, rapidly and for the worse. It surely had to be something more than the number of uncharged particles, which John still judged acceptably low. He kept watching until the simulation reached the time of maximum flux. By then the space shield had become a sieve. In such a future, Earth would suffer far more than during the initial wave of twenty-seven years ago.
His imagination, heightened by the boost, flashed to scenes of disaster made vivid by early childhood. The first effects of the Alpha Centauri supernova had been calving of the Antarctic ice shelf, blizzards at the equator, tidal waves, and nested sets of tornadoes. When the gamma pulse hit, planes dropped from the sky, telephones and television and radio became useless, and mayhem, starvation, and disease took over.
That surprise would not happen again—the gamma pulse would not be repeated. But there was scope for new and worse disasters. His boosted consciousness threw images at him with awful clarity.
The upper atmosphere had shielded Earth from the direct effects of the gamma-ray pulse. It would not do the same for the particle storm now on its way. The charged nuclei, predicted to be mostly bare protons, would come like a hail of tiny bullets, smashing into the air at relativistic speed. Most would be absorbed on the way down, producing a cascade of forward-scattered mesons, electrons, and gamma rays. Some of those would in turn be absorbed and scattered, some would continue. The atmosphere would turn into a cloud of charged nitrogen and oxygen ions, opaque at every wavelength from hard ultraviolet to short-wave infrared. In the darkness below, a deadly blend of radiation and particles would hit the surface. That final mixture would depend on the type and energy spectrum of the incident particles.
Marine organisms would be lucky, at least at first. Water was a fine absorber, and within a few feet of the surface it would quench the main radiation storm. Troubles would begin at the bottom of the food chain, when plankton and algae lacked solar radiation for photosynthesis. Starvation would work its way steadily up, to the krill, to the vertebrate fishes and crustaceans, finally to the seals and dolphins and whales.
Long before that, all land forms would be in trouble. Water was a good absorber for the torrent of high-energy radiation and particles, but unfortunately most plants and animals were at least seventy percent water. Microscopic explosions would happen in a billion cells at once, disrupting protein synthesis and demolishing the delicate nucleotide sequences in the germ plasm. Old organisms would sicken and die, embryos would form with mutation levels high enough to kill, and all under a smoking sky of reactive ions and toxic rains.
Things would improve—slowly. In perhaps a year, when the main storm was over, sunlight would bleed back in and the air would turn clear and clean. Before that, the species die-off might be worse than anything seen during the Permian or Cretaceous/Triassic mass extinctions. Humans ought to survive, but there could be another halving in population, matching that of twenty-seven years ago. Said that way, it didn't sound too bad. Say it as two billion people dying in awful ways, and it became unthinkable.
John's head and stomach were churning. The shield team's job was to make sure that the worst you could imagine didn't happen. But was the team up to the task, even without the new problems?
He turned off the visual feed from Cusp Station. Into the foreground sprang the sunlit upper face of the "space pill," the thin disk of Sky City, a kilometer across and a hundred and ninety meters deep. He was closing on the nerve center for space operations, and he must prepare himself for arrival.
The trouble was, his brain refused to cooperate. The images of Earth's once and future woes distracted him, boiling and bubbling through his mind. John glanced at the condition monitor and understood what was happening. These were Neirling boost side effects, annoying but not unusual. He squeezed his eyes shut and concentrated. After a few minutes the disturbing mind pictures began to fade.
A law of diminishing returns applied to the Neirling boosts. Boost once, and you gained a clean twelve hours of wakefulness and heightened attention. Boost again, before you crashed, and you had maybe eight more hours, with some loss of judgment at the end of it and a danger of making decisions you would later regret. If you tried to stay awake too long in second boost, your consciousness turned off without warning like a failed light bulb.
And third boosts?
They were done only in life-or-death circumstances. The user had at most five good hours, followed by an unavoidable twelve-hour crash. You woke feeling fine. However, observers insisted that the person who came out of a three-in-a-row Neirling boost was not the person who went in. Psychological tests were inconclusive.
John did not intend to add to the body of available evidence. He would go to Bruno Colombo's office and listen to what the Sky City director had to say about the "new problem"—presumably the simulations. After that he would find a place where he could hide away.
Then he would sleep, as soundly as Henry Neirling himself, dead for the past six years.