More than half a century after the destruction of Earth, Io was the first and last line of human security.
Jupiter itself might have fallen to the Machines, but humans still clung to its moons. All the Galilean satellites—the four big moons, Ganymede, Europa, Callisto and Io—were militarised, serving as defence stations as well as armament and fuel factories. An unspoken truth, though, was that everything hinged on Io. This was the nearest large moon to Jupiter, swinging closest to the cloud layers; its hugely energetic surface environment had long supported a key industrial hub. Now the military government had thrown everything at Io, layering it with fortifications and packing sentries, cruisers and battleships into inclined orbits so tight that, in the radar echoes at least, they formed an almost solid shell. Nothing got close to that shell—or through it—without having passed the highest levels of authentication.
And it was not until the Springers’ ship was inside the cordon that Io itself became visible.
Before the coming of people, the surface had been a sickly, mottled yellow brown—the entire moon crusted over with sulphur belched into airless skies from numerous geysers, billions of tonnes of it expelled each year from the vast furnace of the moon’s core. Now, under human occupation, the great energies of Io’s interior had been dammed and diverted, providing power for the war effort. Refrigerated shafts had been sunk into the crust, pushing down through hundreds of kilometres of molten magma, grasping for the hard, hot prize of the core itself. The most troublesome lava flows had been quenched or redirected, or looped into circuits, whichever served human needs the better. Now the geyser activity was down by a factor of two-thirds, with all that surplus energy used in refineries and factories larger than cities, their cooling towers and radiator vanes bristling out to heights of hundreds of kilometres: satanic installations that floated on the impermanent crust like plaques of carbon slag on molten iron. And each refinery or factory was in turn cordoned by an equally extensive battery of weapons. Gun after gun, each squat barrel like a miniature volcano. None had ever been used in anger, for the orbital screens had until now proven unbreakable. Nonetheless they were tested constantly, maintained at hair-trigger readiness.
It was into this military-industrial hell that Howard Falcon now descended.
* * * *
Falcon watched the final approach from the bridge. “So, this weapon of yours. It’s in Io somewhere?”
“Not in Io,” Valentina answered. “Io is the weapon.”
Falcon had long wearied of the Springer-Soames’ clumsily enigmatic bragging. “You’ll have to explain that to me. What will you do, blow up the whole moon?”
“That would be within our capability,” Valentina said. “But it wouldn’t achieve much. A new ring system, a perturbation of the orbits of the other moons, some disruption to Jupiter’s outer cloud layers . . . Our plans for Io are different—grander. You appreciate a grand gesture, don’t you, Howard?”
He wistfully remembered Geoff Webster. “I used to.”
She nodded to her brother. “Do we have entry clearance?”
“Final authorisation just came in. For the last time—are we sure it’s wise to bring him in?”
“He must see the engine,” Valentina insisted. “Then he’ll understand—”
Without warning the ship dived hard for Io, arrowing down through a thicket of towers and vanes towards a smooth, black surface. It was going to take one hell of a pull-up, Falcon thought. And if anything went wrong . . . After all that he had endured, Falcon supposed that it would be a small mercy to die instantaneously, wiped out in a high-speed crash—neatly closing the long chapter of his life that had begun with another crash, eight hundred years ago—as if everything that had happened in between was but the dream of a dying mind.
The ground loomed.
And at the last instant a door irised open in the black surface. The Springer ship slipped through, harpooning down a long, straight shaft, with barely a whisker of clearance on either side. Red lights marked the speed of their descent, clipping past at what must have been several kilometres per second. Brother and sister looked on with a nerveless cool, as if they had done this a thousand times.
Falcon was almost impressed. “I knew you’d tapped the core. I had no idea there was anything this extensive. The pressure pushing back on these walls—”
“Is nothing,” Bodan said. “Nothing compared to what the Machines must be dealing with in Jupiter, at least. Tunnelling through a few thousand kilometres of moon is child’s play.”
“Don’t talk down our achievements, brother,” Valentina chided. “Think of all that bright magma, just beyond these walls, waiting to burst through and reclaim this tunnel we dug out of the rock. Does that scare you, Howard?”
“Other than human wickedness, I’ve more or less run out of things to be scared of.”
“Wickedness? This is total war,” Bodan said sternly. “There are no moral absolutes—no universal reference frames of good and evil. We do what we must to survive. Nothing else matters.”
“Oh, he’s still cross with us about the Memory Garden,” his sister said with a mock pout.
“Then he should get some perspective. There’d be no point commemorating Hope Dhoni if the Machines win. Left to themselves, they’d eradicate every trace that there was ever a prior civilisation in this system at all. We’re vermin to them—nothing more.”
“You misunderstand them,” Falcon protested.
“No,” Valentina answered with a sudden fierceness. “They misunderstand us. They underestimate our resolve—how far we’ll go. To make them understand is the point of the exercise, Howard.”
Turning back to a console, Bodan said, “Coming up on the enclosure.”
The ship began to decelerate. A secondary iris popped open ahead of them, and then they were through, still braking hard, as they emerged into a much larger sealed space. By now, Falcon judged, they must be deep inside Io—perhaps beneath the magma layer, even inside the core itself.
It was clear that the Springer-Soames had been busy.
The space inside Io was an artificial chamber many tens of kilometres across, the curvature of distant walls traced by a haze of fine red lines. And occupying much of the central part of the chamber was some kind of engine, or power plant, scaled up to mountainous proportions. The thing was walnut-shaped, with a kind of axle running through the middle of it, extending out both ends and sinking into colossal plugs on either side of the chamber. In fact, this engine was comfortably larger than any spacecraft or station Falcon had ever seen—larger even than the Acheron—no part of it smaller than kilometres across, the whole titanic assemblage itself the size of a small moon.
And all cunningly bottled inside Io.
The Springer ship, reduced to the proportion of a krill next to a blue whale, nosed slowly along the length of the device. Floodlights picked out areas of detail, with the occasional pinprick flash of a laser or welding tool hinting at ongoing activity. Falcon could see no human workers—they would have been lost in the detail.
“I take it this isn’t some immense bomb?”
“We call it the MP,” Bodan said. “Short for Momentum Pump. It’s a starship engine, in all but function. In fact the basic technology came from research into interstellar travel, the physics and engineering.”
“We already sent starships. The Acorn ships—one of your own ancestors was involved—”
“Toys. The records expunged. For now, we’ve a better use for the technology. What can move an asteroid-sized starship to a quarter of the speed of light can just as easily move a moon. Maybe not as fast or as far—but then again it doesn’t need much of a push.”
“You see, Howard, when the MP is activated,” Valentina said, “it will alter the orbit of Io. Within a few circuits—much less than a week—the moon’s altered course will bring it down. We will smash Io into Jupiter, destroying the moon utterly, of course, but also disrupting the Jovian atmosphere beyond anything it will have known since the formation of the solar system. The Machines won’t survive. Nor will the medusae, or any other element of the Jovian ecology. But that is a price we will willingly accept.” She smiled. “So that’s our cunning plan, Howard. Brutal but effective, don’t you think?”
Falcon struggled to grasp the idea, the sheer scale of it—the audacity—the insanity. “Shoemaker-Levy 9,” he said.
Valentina frowned. “What?”
“A comet that hit Jupiter, long ago. The medusae still sing of that event. But this . . .”
“The medusae will sing no songs of Io, Howard. There won’t be any medusae left.”
“I’ll say this for the two of you. You’re doing a splendid job of turning my sympathies to the Machines.”
“Your sympathies don’t interest us,” Valentina said. “But you do care about the medusae.” She grinned. “We’ll show you we’re serious. We’ll show you what our engine can do. In the meantime, perhaps we should give you time to think it over. You can do that while we have you . . . checked over.”