David Brin - The Heart of the Comet

—It’s not funny, Carl. This gunk could get into a joint, stiffen it up.—

“It’ll evaporate.”

—Yeah? So how come it didn’t boil away four billion years back?—

“It’s been under pressure.”

—But everything must’ve frozen down after the early days.—

“Probably. This was just a flying iceberg for billions of years, out beyond Neptune. But back when the solar nebula condensed there was a lot of aluminum 26 in Halley; Chem Section reported finding the decay products, remember?”

—Oh yeah, residue from the same supernova that triggered formation of the solar system.—

“So they say. Anyway, that aluminum-isotope decay melted these chambers. Might’ve kept things percolating long enough to cook up those exotic chemicals and prelife forms Lintz found. I dunno.”

Lani widened the opening with a pick. —Then when Halley got bumped into its present orbit, the sun warmed up these hot spots again? Waves of heat every perihelion summer?—

Carl shrugged. “Must’ve.” He couldn’t think of a way to maneuver this conversation over to Virginia ’s secrets.

—Last year’s heat from the sun—that must still be seeping down through the ice, adding just enough to keep these local hot spots liquid.—

“Right. Malenkov and Vidor measured the temperature wave.”

The fountain sputtered, died. Cottony clouds swirled, thinned, escaped down the corridor behind them and into the oblivion of space.

“Let’s have a look.” Carl knocked a last rock out of the way and wriggled into the chamber beyond. He fanned his torch around—and gasped.

Crystalline facets sprouted everywhere. Points gleamed ruby red, emerald, burnt orange. Wherever he turned his helmet lamps, refracted light came back in brilliant splinters.

—A crystal palace,—Lani said softly as she followed. —How lovely.—

“The colors!”

—Concentrations of metals? Magnesium? Platinum nodules? Cobalt? The pinks, the purples!—

“Here, take some pictures. Our suit heat alone might melt it.”

—Think so?—Lani handed him her torch and moved away, unhooking her camera. —Look, I can see images of myself in the big crystals. They must be a meter across easy.—

Carl picked his way gingerly, walking lightly on his toes. The peaked pyramids of delicate arsene blue looked particularly dangerous. They worked in skinsuits, thin and flexible enough for difficult jobs, derived from the same woven chain molecules as the corridor liner. Still, a really sharp edge could slice through.

Carl peered ahead, squinting against the rainbow ribbons of light that seemed to focus on him. He remembered an optics problem from Caltech, over a decade ago. If you were inside a reflecting sphere, what would you see? How many images? The natural impulse was to start adding up reflections of reflections of reflections, ad infinitum. The true answer was that you’d see only one image.

Not here, though. Every refraction fed others, giving a myriad swarm of tiny technicolored Carls. They moved as he did, insects of every color hovering in a cloud beyond reach.

Dizzying. Thousands of Lanis, each earnestly working a camera. Between them was a dark spot. He gave a small push and glided over to it.

“Hey. Some kind of fracture here.”

—Careful of these sharp ones, Carl.—

“Yeah.”

He flipped slowly and brought his head down into the hole. “Looks like it goes on.”

—Very far?—

“Dunno. Some runny brown stuff back in there. Looks wet.”

—Yuk. Leave it for the bio boys.—

“Check.” He righted himself. drifting lazily over a glinting field of steepled crystals. “Hey, it’s lunchtime.”

—Let’s eat here.—

“Could get good hot chow back at sleep-slot one.”

She grimaced. —And unsuit just to get inside? Roast pheasant with chestnut sauce wouldn’t be worth having to wipe up this mess an extra time.—

They tethered from the nominal ceiling and broke out food tubes. “Even self-heated, this stuff is pretty bad,” Carl grumbled.

—It’s worth it to me, just to be away from the others.—

“Yeah, know what you mean.”

Their ration was stored in their backpacks, heated there and available by sucking on a tube that emerged near the chin. Eating was not an elegant process. Lani had a curious natural daintiness that made her turn away for each gulp of the light, aromatic broth. She floated with her arms and knees tucked in gracefully, an economical cross-limbed Asian sitting posture, more elegant than the usual spacers crouch. Carl smiled. She was a hard worker, lean and lithe, with steady, remorseless energy.

—I enjoy getting off by ourselves.—

“Uh-huh.”

—Particularly in such a lovely, well… jeweled palace.—

“Right. Damn pretty.” Carl wondered vaguely about Virginia.

—Do we have to tell anyone about it?—

“Huh?”

—Couldn’t it be a place… just for us?—

“Uh, why?”

—To get away. We could come here and bask in the light and, well, have time to talk.—

Carl didn’t feel comfortable with this turn of the conversation. “Look, somebody’d find it fast enough. I mean, we’d have to leave a port exit in the insulation, to get back in here ourselves.”

—Not if we disguised it some way.—

Carl struggled for a reply, some technical reason why it wouldn’t work. “You mean, mark it as a pressure hatch? Something like that?”

—I suppose so.—She studied him intently but said no more.

After a long pause Carl spoke again. “Somebody’d notice. It’d be just like Samuelson to come by, check on us. Pop the seal and make the discovery for himself.”

—You think so?—

“Sure, he’s a straitlaced, um, type.” He had barely stopped himself from saying a straitlaced, by-the-book Ortho . Lani was an Ortho, too, but one of the good ones.

—I suppose we should report it to Planetary.—

“Yeah, Quiverian’ll blow his buttons.”

—Still… I would like to have, you know, a retreat.—

“Plenty of volume in Halley—almost three hundred cubic kilometers.” He couldn’t imagine wanting to spend time sitting in an ice-walled hole, even if it did get you away from the rest of the dozen people in the First Watch. Better to go outside if you wanted that. Have the whole solar system to look at.

—Well, perhaps later, then. We could do it all ourselves, without the mechs.—Lani looked at him with a doelike, expectant gaze. Carl glanced away nervously.

“I dunno. Might have to insulate it.”

Unless he could steer the talk to Virginia, he wanted to deflect conversation away from personal things, to keep their relationship friendly but strictly professional. He started talking about the insulation problem, how much worse it was here than on Encke.

Humans liked temperatures around three hundred degrees Absolute, but some of the frozen gases boiled away in a furious phase transformation around a hundred degrees. Even a casual brush from a skinsuit would bring an answering puff of gas. Maintaining that two-hundred-degree differential had meant developing flexible, layered insulators. The merest breath of air would evaporate the very walls from an uninsulated chamber.

There would always be some boiloff, so the tunnel system had to let the vapor escape toward the surface, where it vented to free space. At the same time, controlled harvesting of the ice was the key to the expedition’s success. The biosphere needed a flux of water, gases, even the metals and grit contaminating the comet. So some of the boiloff was recovered, filtered to keep the cyanide level down, and cycled back into the habitats.

Without a virtually labor-free system to supply fluids and gases, there would have to be more people awake and working. That, in turn, would put more demand on the biomatrix, which drove a spiral of costs. This was the fundamental reason why living inside Halley Core was essential. As usual, profit and loss had the final say.