Bisesa said briskly, “Oh, I don’t think it has anything to do with God.” She stood up. “More coffee?”
“Nicolaus—your target is the Vatican?” But the destruction would be much more extensive than that. A spaceplane returning from orbit packed a lot of kinetic energy: the Eternal City would be hit by an explosion with the force of a small nuclear weapon. She had not felt like crying before, but now tears pricked her eyes: not for herself, but for the destruction that would come. “Oh, Nicolaus. What a waste. What a terrible—”
And then the bomb went off. It felt like a punch in the back.
She was still conscious, for a while. She could even breathe. The cabin had survived, and its systems were doing its best to protect her. But she could feel herself tumbling, and monstrous G-forces pushed her deep into her seat. She could hear nothing; the blast had left her deafened—not that it mattered anymore.
She was falling through the sky, she supposed, trapped in a piece of wreckage thrown out of a fireball high above Rome.
Still she felt no anger, no fear. Only sadness that she would not see the greatest job of her life through to the end. Sadness that she had had no chance to say goodbye to those she loved.
But she had been tired, she thought. So very tired. It was up to the others now.
In the last second she felt a hand creep into hers. Nicolaus’s, a last, raw human contact. She gripped it hard. Then, as the spinning worsened, she blacked out, and knew no more.
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Part 4
26: Altair
The star called Altair is so far away that its light takes more than sixteen years to travel to Earth. And yet Altair is a neighbor, comparatively; only a few dozen stars lie closer to the sun.
Altair is a stable star, but more massive than the sun. Its surface, twice the temperature of Sol’s, glows white with none of the sun’s hint of yellowness, and it breathes out ten times as much energy into the faces of its scattered flock of planets.
Of those planets six are immense Jovians, all but one more massive than Jupiter. They all formed close to the parent star on looping orbits, wheeling like a flock of monstrous birds. But with time the Jovians, plucking at each other with their mighty gravitational fields, gradually migrated outward. Most of them settled into a neat clockwork array of circular orbits. Complex physical and chemical processes churned in the planets’ hot, deep interiors—and, in the tranquillity of eons, on some of those worlds life was spawned.
One planet was different, though.
This swollen monster, fifteen times more massive than Jupiter, was peculiarly unlucky in its interactions with its brethren. It was flung far out of the parent system, on a looping elliptical orbit whose farthest reach took it into the chill realm of comets. This huge orbit took millions of years to complete—and so every few megayears Altair’s huddled family of inner planets was disturbed by the rogue giant’s plummeting visits from the depths of space. Worlds that might have been Earths rolled and quivered, plucked by the rogue’s gravity. Not only that, but the rogue’s passage through Altair’s broad belts of comets and asteroids sent a heavy rain pouring into the inner system. On Altair’s worlds, dinosaur-killer impacts were the norm, falling a hundred times more frequently than on Earth.
In time this process of destruction would have run its course. In the very long run the rogue Jovian would have destroyed the smaller worlds. Or it might have smashed into another Jovian: a catastrophe for both planets. Or, most likely, this moody wanderer would have become detached from the Altair system altogether, perhaps by the passage of another star, and it would have drifted away into sunless space alone.
But there was an intervention.
The most dramatic single event in the formation of the Earth was the mighty collision that shattered the proto-Earth into twin worlds, Earth and Moon. For a few days the glow of the wrecked world was bright enough to be seen over hundreds of light-years.
Those who watched had eyes sensitive to colors for which there are no words in human languages. But they watched nevertheless: they watched everything and everywhere, patiently, indefatigably. And they noticed Earth’s violent birth.
They watched what followed too: the gathering of oceans from comet water, a brief age of chemical churning, the startlingly rapid rise of simple life-forms, the more sluggish progress toward complexity, and at last a glimmer of intelligence. It was a familiar story in its broad thrust, only the details differing from world to world.
But those who watched did not regard this as “progress.”
In an ancient conclave, at levels of discourse no human mind could have comprehended—and despite some dissension—the gravest of decisions was made.
And a weapon was selected.
A sterilizing agent.
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How do you move a planet? There are many ways, but the method used at Altair was well within humanity’s understanding.
It was that rogue Jovian’s very perturbability that made it so useful. Since the 1970s human engineers had been using gravitational “slingshots” to boost their spacecraft on their way. A spacecraft such as Voyager, say, could be “bounced” off Jupiter’s gravity well—and, like a Ping-Pong ball rebounding off the windshield of an eighteen-wheeler truck, if you got the angles right the spacecraft would be hurled away with hugely increased momentum. The space engineers had become expert at this technique, finding ways to use ever more elaborate chains of slingshots to tap into the solar system’s store of energy and momentum and so to reduce the amount of rocket fuel they needed to loft into space.
Because Jupiter was some ten trillion trillion times as massive as Voyager, such encounters had not disturbed the target planet significantly. But if a world comparable in mass to Jupiter had followed Voyager’s trajectory, both incoming and target worlds would have been flung away in new directions.
And here was the principle: to use gravitational slingshots to move worlds.
A single impulse would be difficult to arrange, and wasteful, for much energy would have been dissipated in tidal distortions. But you could use a stream of asteroids to shift the much mightier mass of a planet without such undesirable consequences.
And smaller rocks yet could be used to deflect the asteroids in the first place. A hierarchy of encounters could be arranged, with the tiniest of initial deflections—like a pebble thrown into a pond—causing a sequence of ever more immense disturbances. It helped that the mechanics of many-body gravitational systems were intrinsically chaotic and so sensitive to small disturbances.
It would take planning, of course, to make this multiple cannon shot pay off. But it was only a question of orbital mechanics. It was efficient too, with very little energy wasted. To those to whom economy was a guiding principle, it was a method whose elegance appealed.
The pebble was thrown.
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It took a thousand years for the cascade of interactions to shift the Jovian from its elongated orbit: no more would it trouble the tormented inner worlds of Altair. It would take another thousand years for the Jovian to cross the gulf of space from one stellar sand grain to the next. But that was of no concern. This was a long game.
When it was done, attention was turned away. Those who had intervened would watch the dйnouement; they believed that was their bleak duty. But there was time enough to be ready for that.
On Earth, humans built ziggurats in veneration of their sun, which they still imagined to be a god. And yet their fate was already sealed. Or so those who had intervened believed.