A Time Odyssey Omnibus

by Arthur C Clarke - Stephen Baxter

Three scholars in particular watched it in awe. They called themselves magi, or magoi, which means “astrologers”—stargazers. And in the Jovian’s final days, as it neared the sun and became a morning star of ever more brilliant beauty, they followed it.

  The planet battered its way through the sun’s wispy outer atmosphere, the corona. Now the star itself lay before it, unprotected.

  The Jovian was a planet a fifth the diameter of the sun itself. Even at such speeds, a collision between two such immense bodies was stately. It took a full minute for the whole planet to sink into the body of the star.

  In normal times the sun’s surface is a delicate tapestry of granules, the upper surfaces of huge convection cells with roots in the sun’s deep interior. When the Jovian hit, that complex hierarchical structure was disturbed, as if a baseball had been thrown into a pan of boiling water. Immense waves washed away from the point of impact and rolled around the curvature of the star.

  Meanwhile the planet itself was immersed in a bath of intense heat. Through direct collisions between the sun’s plasma and the planet’s atmosphere, the sun’s energy poured into this outrageous invader. In response, the planet desperately tried to shed heat by losing its own substance. The upper layers of its air, mostly hydrogen and helium, were soon stripped off, exposing the inner layers, exotic high-pressure liquid and solid forms of hydrogen, which in turn boiled away. It was exactly as Apollo capsules had once entered Earth’s atmosphere behind ablative shields, allowing bits of the disintegrating spacecraft to carry away the heat of friction. For the Jovian the strategy worked for a while. The planet had entered the sun with the mass of fifteen Jupiters, and had the capacity to soak up a lot of heat before it was done.

  Deeper and deeper the Jovian sank, through the sun’s roiling convective layer, and then into the denser, static radiative layer beneath. It was like a driving fist, and it left behind a tunnel drilled brutally through the sun’s strata, a flaw that would take millennia to heal.

  By the time the Jovian reached the edge of the sun’s fusing core, it was reduced to a knot of its densest, hardest stuff—and yet it still retained a mass many times that of Jupiter. Here the last of the Jovian’s mass was broken up and dispersed—but not before it struck the core of the sun a mighty blow. There was a vast fusion surge, like an immense bomb going off at the edge of this natural reactor. That great impulse sent shock fronts pushing deep into the fusing core.

  As Eugene Mangles would understand, the core was temperamental, its rate of fusion highly sensitive to changes in temperature. The Jovian was gone, but its impact had created a pattern of energetic oscillations in the core that would persist for millennia.

  Meanwhile on the surface, though the planet had disappeared into the sun’s maw, the point of impact was a place of roiling turmoil.

  On its way into the heart of the star, the Jovian had torn through a sensitive boundary called the tacholine: the boundary between convective and radiative zones. The dull sea of the radiative zone rotates with the sun’s core, almost as a rigid body. But the convective zone’s motion is much more complex; different parts of the sun’s surface can actually be seen to rotate at different speeds. So, at the tacholine, there is friction: the convective material moves over the radiative like a tremendous wind.

  The sun is laced by a powerful magnetic field. Its interior is full of “flux tubes,” currents of magnetic energy that flow through the plasma sea. At the tacholine the differing rotations of the sun’s layers stretch the flux tubes around the sun’s equator. Mostly the churning convection above keeps them in their place. But sometimes a kink will develop in a sun-girdling rope, and it will force its way up toward the surface of the sun, dragging plasma flows with it. This is the sequence of events that leads to the “active regions” that give rise to flares and mass ejections.

  So it was now. The Jovian’s crashing through the tacholine caused the stretched and tangled field lines to writhe like snakes. Flux tubes surged up through the body of the sun, broke the surface, and thrashed above the enormous scar left by the Jovian. Energy was dumped into space in a great flare of light, as high-frequency radiation, and in a fountain of charged particles that gushed out across the solar system.

  A huge solar storm battered at the Earth. With the planet’s own magnetic field flapping like a loose sail, immense auroras were visible all across the world. The Jovian’s most severe effects lay far in the future. But right here, right now, it announced its arrival in uncompromising fashion.

  On Earth in 4 B.C. there was no high technology to be harmed—but millions of natural computers, running on biomolecules and electricity, were subtly affected by the magnetic turbulence. People suffered blackouts, fits, seizures; some unlucky souls died of no cause anybody could detect. As Miriam Grec would learn to her supreme cost, magnetic disturbances can stimulate religious impulses in human brains: there was a plague of prophets and doomsayers, miracles and visions.

  And in a shabby room in Bethlehem, a newborn child, lying on dirty hay, stirred and gasped, tormented by images He could not comprehend.

  30: TELESCOPE

  Ever since President Alvarez’s devastating announcement in December 2037, the sunstorm crisis had been oddly bound up with Christmas. The last Christmas before the sunstorm, in 2041, with only four months left before the storm was due to break, was a frenzy of forced gaiety. Bisesa suspected that everybody was secretly glad when it was over.

  As for herself, she bought a telescope. And one bright morning in January 2042, with the help of Myra and Linda, she hauled it up to the roof of her apartment block. On this January day, bright and clear, the sun was low in the eastern sky, and the view from this Chelsea rooftop was spectacular. The Dome’s buttresses gleamed like sunbeams, and the smartskin blankets draped over every exposed surface shone like so many huge flowers.

  The telescope was a ten-centimeter refractor, secondhand, a big clunky thing more than twenty years old, and it was cheap. But it was smart enough that it could determine its own position and attitude by consulting the Global Positioning System. And then, if you told it what you wanted to look at, with a hum and a whir it would point itself that way and immediately begin tracking, compensating for the Earth’s rotation. Linda had laughed at the gadget’s antiquated user interface—it actually featured that comical horror, a menu system—but it worked well enough.

  In central London, with an increasing fraction of the sky blocked out by the Dome, telescopes were of little use, unless you wanted to spy on the gangs of workers who crawled over the inside of the Dome’s roof day and night. But what Bisesa wanted to look at was the sun.

  When Bisesa told it what she wanted to see, the telescope’s nanny software immediately started bleating warnings about safe usage. Bisesa already knew all about the dangers. You couldn’t look directly at the sun through a telescope, unless you wanted your eye burned out, but you could project an image. So Bisesa brought up a folding chair and set up a broad sheet of white cartridge paper behind the telescope’s eyepiece. The final positioning of the paper in the telescope’s shadow, and the focusing of the instrument, was a little tricky. But at last, in the middle of the telescope’s complicated shadow, a disk of milky white appeared.

  Bisesa was surprised by the clarity of the image, and its size, maybe a third of a meter across. Toward the rim of the disk the brightness faded a little, so she had a clear sense that she was looking at a sphere, a three-dimensional object. Sunspot groups were speckled around the sun’s midlatitudes, easily visible, looking like motes of dust in a shining bowl. It was galling to think that each of those dwarfed dust-speck anomalies was larger than the whole Earth, and, glowing at temperatures of thousands of degrees, they showed as shadows only because they were cooler than the rest of the sun’s surface.

  But it was not sunspots that Bisesa had bought her telescope to see.

  A line crossed the face of the sun, a stripe of watery gray that traversed from northeast to southwest. It was, of course, the shield. Hangi
ng up there at its station at L1, it was still turned almost edge-on to the sun. But already it cast a shadow on the Earth.

  Bisesa hugged Myra. “You see? There it is. It’s real. Now do you believe?”

  Myra stared at the shadow. Now thirteen years old, she was a bit too quiet for her age. Bisesa had meant this display to comfort Myra, who was not alone in having trouble believing in the reality of the great project in space.

  But her reaction wasn’t what Bisesa had anticipated. She seemed afraid. This was a human-made object, four times as remote as the Moon, and yet visible from Earth. Standing here in the watery sunlight of a London morning, the cosmic vision was astonishing, awe inspiring—crushing.

  This is why the Greeks coined the word hubris, Bisesa thought.

  31: PERSPECTIVES

  For lovers, zero G was a lot trickier than the low gravity of the Moon.

  That was despite decades of experience, Siobhan had learned. In the days of low Earth orbit flights there had been something called the “Dolphin Club,” so named because in the analogous conditions of floating in the ocean, a dolphin couple would sometimes be helped in their intimacy by the bracing support of a third… Siobhan was the Astronomer Royal; she wasn’t about to put up with any of that.

  So Bud had improvised equipment to enable her to retain her privacy. With its cuffs, ropes, and restraints his cabin now looked like a bondage parlor, but in giving you something to grip and push against, this stuff supported the ancient arts surprisingly well. But in the isolated little zero-G township of the shield Bud had clearly had help figuring all this out. She made him take down the little plaque above his bed:

  COURTESY OF

  U.S. ASTRONAUTICAL ENGINEERING CORPS

  ENJOY!

  Still, the sex was as deep and rich and satisfying and, damn it, comforting as ever; she was old enough to admit she needed consolation as much as passion.

  Afterward, though, as they lay under a thick blanket, with Bud a silent warm mass beside her, her thoughts turned to the reasons she had come here.

  This cabin had once been a storeroom; you could still see the marks where shelving and cupboards had been ripped off the walls. Over the years Aurora had been cannibalized, and now it was a husk containing nothing but life support systems, comms centers, and hastily improvised living quarters. But to Bud, she knew, this battered old ship was home. Even when the project was over, no doubt he would always miss it.

  It was going to break his heart if she had to bring him home before the job was done. But that was one possible outcome of her visit, and they both knew it.

  Bud said at last, “You know, at times like this I still miss a cigarette.”

  “At heart you’re just an unreconstructed high school jock, aren’t you?”

  “Salt of the earth.” He stared at the ceiling. “But this trip is business, not pleasure, isn’t it?”

  “I’m sorry.”

  He shrugged. “Don’t be. But look—as far as everybody else is concerned, you’re here for the AI switch-on. Nobody but my PA knows about the other stuff.”

  Faintly irritated she said, “I’m not here to hurt morale, Bud. I’m supposed to be strengthening the project, not weakening it. That’s the whole point. But—”

  “But this business of the audit has to be cleared up.” He held her hand. “I know. And I trust you to handle it well.”

  She churned with guilt. “Bud, we both have our duty. And we can’t let anything get in the way of that.”

  “I understand. But a bit more pleasure before business.” He sat up. “We’ve got twelve hours before we boot up the AI. Let’s go do some sightseeing.”

  They washed, dressed, and drank a coffee. Then Bud escorted her to the little ship he called the V-Eye-P.

  The project’s one and only one pressurized inspection module was just a platform laden with spherical fuel and oxidizer tanks and a small set of hydrazine rocket motors—actually attitude thrusters cannibalized from a retired spaceplane. On top was a pressurized tent of Kevlar and aluminum, within which two people could stand side by side. That was it, save for a simple set of controls based on a joystick that sprouted from the floor, and a life support system that would keep you alive for six hours at a pinch.

  The shield engineers used variants on this design, but just the platform and the engines, without the tent: why bother with a pressure cabin when you had a perfectly good spacesuit? So you would see engineers skimming over the surface of the shield riding their rocket-propelled boxes like scooters. Only this one special little craft was kept aside for VIPs, visitors like Siobhan who didn’t have the time or inclination to get trained up on how to use a pressure suit.

  “Not,” Bud said with a faintly malicious grin, “that this Kevlar tent would be much protection if anything went wrong…”

  The V-Eye-P was launched from Aurora by an electromagnetic induction rail, like a miniature version of the Sling, the giant mass driver on the Moon. The acceleration was smooth, like a rapid elevator; Siobhan quite enjoyed the feeling of her feet being pressed to the floor.

  When they had climbed sufficiently far, Bud tested the little ship’s rockets, “burping” them as he called it. It sounded as if small explosions were going off all around the Kevlar hull. Bud explained that there was no exhaust from the induction rail, and rockets, however small, were never used close to the shield. “We’re building a mirror made of frost laced on spiderweb,” he said. “We try not even to breathe on it.”

  The craft swiveled and pitched to and fro. It was like being aboard a rather odd fairground ride.

  When he was satisfied, Bud brought the craft to a halt and tipped it forward so Siobhan could see down. “Behold the mother ship,” he said.

  The venerable old Aurora 2 was still the centerpiece of the shield, still the spider at the center of the web. Despite extensive cannibalization, Siobhan could make out the main features she remembered: the long, elegant spine with the fat habitation module at one end, and the complex clusters of power plants, fuel tanks, and rocket engines at the other. “She’s a game old bird,” Bud said fondly. “I hope she forgives us. She still has a role to play, keeping the shield spun up and oriented correctly. Of course all that will change when the AI comes online and the shield starts to control itself.”

  He pulled back on his control stick, and the platform’s thrusters banged. The little ship rose up smoothly, rising away from the shield along an axial line that led straight up from the embedded Aurora.

  Siobhan stared out, fascinated, as the shield opened up beneath her. Away from the old Mars ship the shield was a floor so flat and smooth it was like a mathematical abstraction, a semi-infinite plane that cut the universe in half. The surface shimmered, as delicate as a soap bubble, and as she rose higher prismatic rainbows fled across the surface. But the shield was still edge-on to the sun, and the low light streamed through that delicate membrane, so that she could make out the spindly skeleton beneath, struts, spars, and ribs of delicate lunar glass, a fairyland scaffolding that cast long, slim shadows.

  “It’s wonderful,” she said. “The most massive engineering project anybody ever undertook, and yet it is nothing but glass and light. Like something from a dream.”

  “Which is why,” Bud said a bit mysteriously, “I’ve chosen the name I have for her—the shield’s AI, I mean.”

  Her? But he would say no more.

  He pulsed the attitude control thrusters again and tipped the platform backward, so its windows swiveled to face the Earth. The home planet was a perfect blue marble hanging in space. The Moon, white-brown, sailed beside its parent, some thirty Earth diameters away. L1 was far beyond the orbit of the Moon; from here, there was no doubt this was a twin world.

  “Home,” Bud said simply. “Stuck out here it’s good to be reminded of what we’re working our butts off for.” He leaned close to her, and pointed so she could sight along his arm. “See there? And there?…”

  Against the velvety darkness of space she saw sp
arks drifting, two, three, four of them in a rough line, like fireflies in the night, passing from Earth to shield.

  Bud tapped the window. “Magnification please.”

  The image in the window before Siobhan exploded in rapid jumps. Now she could see perhaps a dozen ships. Some were just large enough to show detail, hull markings, solar-cell arrays, antenna booms. The convoy looked like toys, models suspended against velvet.

  “A caravan from Earth, bringing up the smartskin.” Bud was grinning. “Crawling its way up the gravity hill to L1. Isn’t that a fantastic sight? And it’s been going on, day and night, for years. If you turn a scope on the dark side of Earth, you can see the sparks of all those launches, over and over.”

  On the ground, Siobhan had inspected the collection processes. Smartskin blankets, grown out of household windows like Bisesa Dutt’s in London, were gathered at neighborhood collation points, and then shipped to big storage centers at the airports and spaceports, and finally bundled up and sent to one of the great launch centers at Cape Canaveral, Baikonur, Kourou, or Woomera. Just the ground operation was a stupendous enterprise, a mighty international flow across the face of the Earth. And it culminated in these sparks bravely crossing the night.

  Bud said, “You know the picture. We’re throwing everything we’ve got into the launches, just like every other aspect of the project. They even dug the space shuttles out of their museums at the Smithsonian and Huntsville, and got those beautiful birds flying again. Worn-out shuttle main engines, too beat-up to be human-rated anymore, are being recycled: you can make a pretty useful throwaway booster out of a shuttle tailplane and a cargo pallet. The Russians have brushed off their old plans for Energia and have got those big old rockets flying again too.

  “But even that isn’t enough. So Boeing and McDonnell and the other big contractors are churning out boosters like sausages. Why, some of those new birds aren’t much more sophisticated than a Fourth of July firecracker, and all you can do is point and shoot. But they work, with nearly a hundred percent reliability. And we’re getting the job done…”