“There are just so many of them,” somebody said. “If the whole of the rim wall is like this — miles of it — there must be billions of them.”
“It’s an old colony,” Dower said dryly.
The shuttle swam on, heading toward the central mountain.
On the edge of a lake of frozen oxygen, the shuttle landed as gently as a soap bubble. Dower ordered a skinsuit check — each trooper checked her own kit, then her buddy’s — and the walls of the shuttle popped to nothingness.
Gravity was about standard. When Abil clambered off his small T-shaped chair he dropped the yard or so to the ground without any problem. He walked around, getting the feel of the ground and the gravity, listening to the whir of the exoskeletal servers built into his suit, checking telltales that hovered before him in a display of Virtual fireflies.
Around him a hundred troopers did likewise, stalking around the puddle of light cast by the shuttle’s floods. Their backpacks glimmered murky green, the color of pond water.
Abil walked out to the edge of the light, where it blurred and softened to smeared-out gray. The water ice was hard under his feet, hard and unyielding. The surface of the frozen ocean was dimpled and pocked. Here and there frost glimmered, patches of crystals that returned the lights of his suit, or of the stars. The frost was not water but frozen air.
Oxygen, of course, was a relic of life. So there must have been life here — life that mightn’t have been so different from Earth-origin life — long gone, crushed out of existence as the sun receded and the cold’s unrelenting fist closed. Perhaps that life had spawned intelligence: perhaps this world had once had a name. Now it only had a number, generated by the great automated catalogs on Earth — a number nobody ever used, for the tars called it simply “the Target,” as they called every other desolate world to which they were sent.
“Gather ’round,” Dower called.
Abil joined the cluster of troopers around Dower. He found his own unit, marked by red arm stripes. He joined them, showing his command stripes of red and black.
“Look here.” Dower pointed to the edge of the oxygen lake.
Footprints, on the water ice shore: human prints, made by some heavy-treaded boot in a shallow nitrogen frost, quite clear.
“The warren’s bio systems are probably highly efficient recyclers, but nothing is perfect. They still need oxygen …”
Abil walked up to the prints. His own foot was larger, by a few sizes. Standing here, he saw that the prints led back, away from the oxygen lake, forming a path that snaked almost dead straight toward the central mountain. And when he looked the other way, beyond the lake, he saw more trails leading off toward the rim, the circular heap of corpses.
Those striations he thought he had seen on the ice, radiating inward from the rim wall, were actually ruts, he saw now, worn into water ice as hard as granite by the passage of countless feet, over countless years. All those journeys, he thought, shuddering, out to that great heaped-up pile of mummies. Year after year, generation after generation.
Dower hefted a weapon. “This is our way in. Form up.”
Abil stood at the head of his unit. Briefly he surveyed their faces. There were ten of them, all friends — even Denh. They would support him now to their deaths. But his stripes were only provisional, and he knew that if he fouled up they would chew jockey to replace him for the next drop, wherever and whenever it was.
That wasn’t going to happen. He grinned tightly. “Reds, forward.” They formed into two rows, with Abil at the head.
They trotted along the line of the path in the ice, keeping to either side of the rut, heading steadily toward the central mountain. The going turned out to be treacherous. Even away from the main paths the ice was worn slick by the passage of human feet. There were a few stumbles, and every so often there was a silent burst of vapor as somebody stepped into an oxygen puddle. Every time one of his unit took a pratfall Abil called a halt to run fresh equipment checks.
After about a mile Dower paused. The rut had led them to a crater in the ice, maybe ten yards across — no, Abil saw, the edges of this shallow pit were too sharp for that, its circular form too regular, and the base of the pit was smooth, gunmetal gray. Dower pressed her finger to the surface, and read Virtuals that danced before her Eyes. “Metal,” she said. She beckoned to Abil. “Corporal. Find a way in.”
He stepped gingerly onto the metal surface. It was slick, and littered with bits of loose frost, but it was easier than walking on the ice. He sensed hollowness beneath his feet, though, a great volume, and he trod lightly, for fear of making a noise. He knelt down, pressed his palm to the metal surface, and waited. Where his knee touched the metal he could feel its cold, clawing at him through the diamond pattern of heating filaments in his skinsuit. It took a few seconds for results from his suit’s sensors to be displayed, in hovering Virtuals before his face.
He was rewarded with a sketchy three-dimensional cross section. The metal plate was a couple of yards thick, and much of it was solid, fused on a base of rock. But it contained a hollow chamber, an upright cylinder. Probably some kind of low-tech backup system. The covering for the hollow was no more than a couple of yards away.
He walked that way and knelt again. His fingers, scraping over the sheer surface, quickly found a loose panel. By pressing on one side of it, he made it flip up. Beneath that was a simple handle, T-shaped. He grasped this, tugged. A lid rose up, attached by mechanical hinges.
Abil peered into the pit, using his suit lights. The pit was a little deeper than he was tall. He saw a wheel in there, a wheel set on a kind of spindle. Its purpose was obvious.
Dower came to stand beside him. She grunted. “Well done, Corporal. Okay, let’s take a minute. Check your kit again.” The troopers, working in pairs, complied.
Dower pointed at the mountain. “You were right — uh, Denh. The mountain’s tectonic, not impact- created. We’re standing over a midocean ridge: a place where the crust is cracking open, and stuff from within wells up to form new ocean floor. And where that happens, you get mountains heaping up, like this. On this planet it’s still happening. The loss of the sun destroyed the surface and the air, but it made no difference to what’s going on down deep. All along this ridge you will have vents, like valves, where the heat and the minerals from within the planet come bubbling up. And that heat will keep little pockets of water liquid, even now. And where there’s liquid water—”
“There’s life.” That mumble came from a number of voices. It was a slogan from biology classes taught to five-year-olds, all across the Expansion.
“And that is the ecosystem that will have survived this planet’s ejection from its solar system: something like bacteria colonies, or tube worms perhaps — probably anaerobic, living off the minerals and the heat that seeps out of the cracks in the ground. Radioactivity will keep the planet’s core warm long after that lost sun itself has gone cold. Strange irony — life on this world will probably actually last longer than if it had stayed in orbit around its sun …”
Abil piped up: “Tell us about the warren, sir.”
She began to sketch with one finger in the loose ice. “The warren is a rough toroid dug into the ice, encircling that central peak. In places it’s nearly a mile deep. It’s not a simple structure; it’s a mess of interconnected chambers and corridors. We suspect the birthing chambers are the deepest, the closest to the mountain rock itself; that’s the usual arrangement.