Pirius watched Callisto’s approach. It was a ball of white, quite featureless to the naked eye, lacking even impact craters as far as he could see. But it was surrounded by a deep, diffuse cloud of drones. Some of them swam close to the corvette. They were fists of metal and carbon that glistened with weapons.
Nilis said, “A deep defense system. Even Earth itself doesn’t have such aggressive guardians.”
“And very old,” Luru Parz said. Even she seemed tense as the corvette descended through the cloud. “This cordon was first erected during the lifetime of Hama Druz himself — following Druz’s own visit here, in fact.”
“I didn’t know Druz had come here,” Pirius said. He actually knew very little about the moral founder of the Third Expansion.
“Oh, yes,” Luru said. “And what he found here shocked him into the insights that led him to formulate the famous Doctrines — and to order Callisto to be cordoned off. This little moon is a key site in the history of mankind. Twenty thousand years have worn away since then, and the whole setup has been subject to the implosion of a black hole a few light-seconds away. Some of these old drones may be a little cranky. They have been instructed to recognize us. But…”
“How ironic,” Nilis said grimly, “if we were to be thwarted by a malfunctioning antique robot.”
“There are many in the Coalition councils who wouldn’t shed a tear to see the back of me — or you, Commissary.”
The ship continued to descend. The icescape of Callisto flattened out to a frozen ground streaked with color, pale purple and pink; perhaps the ice was laced with organic compounds. It was smooth as far as Pirius could see, smooth all the way to the horizon. But a shallow pit was dug into the ice, and at the center of the pit there was a settlement of some kind, a handful of buildings and landing pads.
Luru Parz said, “Once Callisto was just a moon, you know. It was peppered with impact craters, like every other moon — not like this. At this site there was a major crater called Valhalla — I don’t know what the name means — and in the time of Michael Poole there were extensive ice mining projects. But it all changed after Hama Druz’s visit.”
Pirius said, “What happened to the craters?”
“What do you think?”
He thought it over. “The surface looks as if it melted. What could melt a moon?”
“It was moved,” said Luru Parz, watching him. “In the process the surface shook itself to pieces.”
“Moved…” Pirius knew of no technology which could achieve such a thing.
Nilis prompted, “And the reason we are here—”
“This was the last refuge of many jasofts,” Luru Parz whispered. “And here is stored their oldest knowledge. But it will take a sacrifice to retrieve it.” She wouldn’t look him in the eyes, and Nilis looked away.
Pirius still had no idea what they wanted of him. Despite his training, dread gathered in his belly.
The corvette passed through the last line of the drones and began its final approach.
Pirius descended into the deep core of Callisto.
He rode an elevator with Nilis, Luru Parz, a servant bot, and a taciturn Navy guard. They passed down a shaft cut into the ice, its walls worn smooth. Pirius touched the walls; the ice was slick, cold, lubricated by a layer of liquid water. Beneath a surface patina of dust and grime he saw that the ice had a structure, a lacy purple marbling, receding into meaningless complexity. More strangeness, he thought.
It was cold, surely not much above freezing, and their breath fogged air that stank, stale. The elevator, a simple inertial-control platform, was itself an antique, and as it descended it shuddered and bucked disconcertingly. He felt as if he was being dragged down into the strata of time that overlaid every world in this dense, ancient system.
They arrived in a chamber cut deep in the heart of Callisto. Only the handful of floating globes which had followed them down the shaft cast any light, and the party huddled, as if nervous about what might lurk in the dark.
Pirius stepped off the platform. The chamber was a rough cube maybe twice Pirius’s height, crudely hollowed out. It might almost have been a natural formation, save for notches in the floor, and a regular pattern of holes in the wall. The only piece of equipment he could see was a kind of door frame, set purposelessly in the middle of the floor.
Luru Parz walked over the ice. “Once this was a mine. Nothing more sinister than that. But when I was last here the mine had long been shut down. Chambers like this, and the tunnels and shafts that linked them, had been pressurized and occupied. There was equipment here.” She pointed to notches in the floor. “That was a kind of bed, I remember.”
Pirius had been expecting something like Mons Olympus, some kind of library with bots and toiling archivists, Coalescent or not. “There’s nothing here,” he said. “Was this the library?”
“This never was a library,” Luru Parz said. “This was a laboratory.”
“Then where?”
“Through there.” She pointed to the door that led nowhere.
There was a moment of stiff silence, as Pirius looked from one to the other. He said, “I think you ought to tell me what’s going on.”
Nilis stared at him, agonized. Then, his arms tucked into his sleeves, he padded to the bot. The bot’s carapace opened to reveal a tray of drinks that steamed in the cold. Nilis picked one up, cradling it in his hands. “Lethe, I need this. What a tomb of a place!”
Luru Parz watched this with contempt. “A man called Reth Cana worked here, Ensign. Long ago. Ostensibly he came to look for life…”
Before humans came, nothing much had happened to this moon since it accreted from the greater cloud that had formed the Jupiter system. The inner moons — Io, Europa, Ganymede — had been heated by tidal pumping from Jupiter. Europa, under a crust of ice, had a liquid ocean; Io was driven by that perennial squeezing to spectacular volcanism. But Callisto had been born too far from her huge parent for any of that gravitational succor. Here, the only heat was a relic of primordial radioactivity; there had been no geology, no volcanism, no hidden ocean.
Nevertheless, Reth Cana had succeeded in his quest.
They were cryptoendoliths, Luru said, bacteria-like forms living hidden lives within the dirty ice of Callisto. They survived in rivulets of water, kept liquid by the heat of relic radioactivity, and they fed off the traces of organic matter locked into the ice at the time of the moon’s formation.
Luru Parz said, “The biochemistry here is a matter of carbon-carbon chains and water — like Earth’s, but not precisely so. Energy flows thin here, and replication is very slow, spanning thousands of years. The cryptoendoliths themselves weren’t so interesting — except for one thing.”
Reth had believed there were pathways of chemical and electrical communication, etched into the ice and rock, tracks for great slow thoughts that pulsed through the substance of Callisto. Locked into their ice moon, there had been few routes of development open to the cryptoendoliths. But, as always, life complexified, and sought new spaces to colonize. “The cryptoendoliths couldn’t move up or down, forward or back. So they stepped sideways…”
Nilis asked coldly, “Was Reth Cana an immortal, Luru?”
“A pharaoh, yes. But not a jasoft, not a collaborator. He was a refugee, in fact; he came here fleeing the Qax, and waited out the Occupation. Of course, as soon as the Occupation was lifted, he became a refugee once more, hiding from the Coalition and its ideologies. He returned here to escape. And he helped others do likewise.”
Pirius said, “What do you mean, these bugs grew sideways?”
“I mean,” said Luru Parz, “that these remarkable little creatures found a way to penetrate another universe. And not just any old universe. Ensign, do you know what is meant by configuration space?”