XIII

The Michael Ventris slowly settled out of orbit under the feathery tug of Amalthea’s gravity, until its flat tripod feet sank deep into the frothy surface. In the equipment bay the ice mole hung lightly in its shackles, lit by the metallic glare of worklights. Blake and Forster pulled themselves into its cockpit and methodically strapped themselves in. The gin­gery professor was seething with impatience.

“Quaint old gadget,” Blake muttered placidly, regarding the gaudy display panel now lit up like a carnival midway. He fiddled interminably with the instruments while Forster, who had been edgy throughout the tedious pre-launch, grew increasingly tense.

“Got an old mole here, do we?” came Josepha Walsh’s hoarse and cheerful voice over the comm.

“This Old Mole’s still got plenty of get up and go,” Blake said at last. “Diagnostics give us a clean slate. Ready to launch.”

“Let’s get on with it,” Forster said.

“All set, Jo?” Blake said in the general direction of the mike.

For a moment there was silence on the commlink before Walsh replied. “That’s a roger. You may proceed.”

Blake brought the clear bubble down over their heads and sealed it. “Confirming full atmospheric pressure, no dis­cernible leaks.”

“You’ll be fine as long as you’ve got your E-units,” came Walsh’s reply. Against sudden pressure loss they wore emer­gency soft-suits, with the faceplates of their head-fitting helmets left open. The mole was of too early a vintage to be equipped for Artificial Reality suits, with which a pilot could feel wholly a part of the machine.

“I hardly think we’re going to die of depressurization,” Forster said sharply.

Blake gave him a quick glance. Perhaps it was the sense of separation, the need for layers of protection and inter­pretation between him and the environment, that made the professor so irritable. Perhaps he was reminded of his near-disastrous expedition to Venus.

“I’ll not hold you up any longer then,” said Walsh. The clamshell doors of the equipment bay peeled away—

—opening upon stars above and unearthly white mist below, and on the horizon a ruddy glow, Jupiter itself riding unseen beneath the moon’s edge.

The whine of a miniature electric crane conveyed itself through the grapple to the roof of the vehicle as the mole was lifted ever so slowly out of the hold and held poised, outside the ship. The whine ceased. There was a click as the last magnetic grapple let go. Then another click, as springs uncoiled and gently propelled the machine away from the ship. Almost but not quite weightless, the massive machine slowly began to drop, nose down. It fell a long time into the mists, like a sagging helium balloon, interminably.

An edge of the huge alien antenna came out of the milky whiteness on the port side. The Ventris had purposely dropped the mole beside the antenna, for here the ice sam­ples showed patches anomalously younger than Amalthea’s otherwise uniform age of a billion years.

Blake and Forster hardly felt the slow collision with the delicate ice when they hit the surface—but outside there were sudden snowdrifts, halfway up the cockpit window.

Above and behind them, barely visible through the frosty window, two white shapes gleamed like portly angels, drifting down the black sky—Hawkins and Groves, checking the fat, half-coiled electrical cables that would power the mole from the Ventris’s auxiliary power units. They did what they had to behind the ice mole, securing the cable attachments.

“Okay, you should be mobile,” came Hawkins’s jolly voice over the commlink. He had gotten over his awkward­ness in spacesuits; indeed, with a day’s practice he’d become quite the athlete of the vacuum.

“We’re all go here,” Blake reported to the Ventris.

“And all links look good on our boards,” said Walsh from the flight deck.

Forster said tensely, “You may go ahead when ready.”

Blake eased the pots forward.

Below them opposed twin bits began an intricate dance, slowly at first, then with rising speed. A cloud of ice crystals engulfed the mole. The top ten or twelve meters were spongy froth, then there was a bump, and the machine abruptly descended through a pocket of vacuum-pocked ice. Finally, with a screech, diamond-edged titanium blades engaged old, hard ice, and the mole began to drill straight into the heart of Amalthea.

Forster suddenly relaxed, releasing a long sigh, as if he’d been holding his breath. The center of Amalthea tugged at his heart, harder the closer he got to it—like gravity, the force of his obsession increased with decreasing distance from his goal. But at least he was moving as fast as he could toward the object of his desire.

The big screen in the middle of the console gave Blake and Forster a clear three-dimensional image of their sector of the moon’s structure—where they were and where they were going. Along with information from a year’s worth of passive observation by Space Board satellites, the results of the Ventris’s recent seismic studies had been fed into the mole’s data banks. Had Amalthea been anything but a thor­oughly surprising place, the image on the screen might have been unexpected. . . .

For over a century, since it was first photographed close up by the primitive robot probe Voyager 1, Amalthea had been thought to be low in volatile substances—certainly a reasonable hypothesis, for the moon had no atmosphere, was rigid, seemed inert. By contrast, its much larger neigh­bor, Io, was a moon so rubbery, so rich in mutable liquids and gases, that remarkable sulfur volcanoes had been in constant eruption somewhere upon its surface ever since they had been discovered by the same Voyager 1, the first artificial observer to reach Jupiter’s orbit and the first, upon returning images of Io to its controllers, to reveal that the Earth was not alone in the solar system in being geologi­cally active.

But Amalthea was in fact about as volatile as a small body can be, consisting almost entirely of water; yet even while bathed in Jupiter’s radiation belts and racked by the tidal forces of the giant—a planet so massive it fell not far short of self-ignition into a star, and thus had often been described as a failed rival to the sun—Amalthea had re­mained frozen solid.

It takes energy to keep water frozen when the surround­ings are hot. After all pertinent data had been fed into the Ventris’s computers it was learned that the apparent dis­crepancy in Amalthea’s energy budget was due not to anything so paltry as a leakage of electrical energy from its radio antennas but to the considerably larger output of what, for want of better name, the expedition called its “re­frigerator.”

A refrigerator is really a heater that heats one part of the thing to be cooled until it is hotter than its surroundings, moving heat from the source to a sink or a radiator. The dark red dust of classical Almathea made a fine radiator, a surface from which the moon could rid itself of the heat it removed from its underlying ice. Most of the heat loss was disguised in the flux of Jupiter’s radiation belts; for more than a hundred years no one had suspected that diminutive Amalthea was adding measurably to the total energy of the belts themselves.

But where was the source?

The Old Mole’s graphics program had its limits—one had to severely restrain it from pretending to more certainty than it really had, when the input was from soft data—so the computer-generated map only sketchily showed that a spheroid of uncertain composition and dimension lay in the core of the moon. For a billion years, presumably, this object had produced the energy necessary to keep Amalthea frozen solid.

A year ago Amalthea had begun to unfreeze. But the moon was melting far faster than radiation belts or tidal forces could account for. Amalthea was melting because the core object had increased its heat output by several orders of magnitude. The refrigerator had turned into a stove.

This was what the seismologically generated map of Amalthea on the console displayed: a rind of solid ice, pierced by vents of gas and liquid, its surface subliming into vacuum. A mantle of liquid water, thirty kilometers deep. A core of hard, hot matter, composition unknown, but hot enough to boil the water that touched it.

The ice mole would come nowhere near that hot inner core, of course. The mole’s function was simply to pierce Amalthea’s frozen crust.

A slurry of sludge and chips blown back from the blades clumped and writhed over the Polyglas canopy, making it seem as if something out there was alive, but beyond the walls of the smooth-cut shaft there was nothing but dense ice.

“Almost there,” said Blake.

“Don’t slow down,” Forster said, as if anticipating some uncharacteristic caution on Blake’s part. Forster tugged at his nose and muttered little ruminative wordless bleats, watching the image of the ice mole boring closer to the bright boundary of ice and water.

Forster was sure he knew what that thing in the middle of Amalthea was, although he hadn’t known a thing about it until they’d finally started getting the hard data a few days ago. Years had passed since his conviction had started him on the difficult path to these discoveries.

The view through the window was almost total black­ness, relieved only by reflected light from the cockpit in­struments; the view on their screen vividly depicted the mole grinding its way straight down through the ice. Behind it, liquified ice flashed into vapor and was propelled up the shaft. But to Forster’s imaginative eye, the deeper they got the more the surrounding ice seemed to glow with some faint and distant source of radiance.


Up on the flight deck of the Ventris, the same recon­structed graphic from the mole’s mapper was available on the big screens, alongside the projection of the Ventris’s more powerful and sophisticated seismic-tomography program. Here there was nothing uncertain—within the limit of resolution of sound waves in water—about the size and shape of Amalthea’s crust or the object at its core. On these screens were incorporated the dimensions, temperature, density, and reflectivity, at every depth, of multiple imagi­nary slices through the moon. Yet even on Ventris’s screens the core was represented as a black hole. For the core object was almost perfectly absorptive of sound waves.

The boiling hot water around it was pictured with perfect clarity, in false colors that showed the intricate eddies and jets surrounding the core. But no image of the inside of the core was possible; whatever it was made of either did not transmit ordinary vibration or somehow actively damped the vibrations of the seismic disturbance that buffeted it on every side.

Over Jo Walsh’s shoulder, Tony Groves watched in fas­cination as the mole descended. “Caution now, caution now.” His voice was almost a whisper.

Walsh pretended to take him at his word. “The navigator urges caution,” she said into the commlink.

Groves reddened. “Now Jo, we don’t want . . .” He let his sentence dribble away.

“What’s that, Tony?” she asked.

“Silly thing . . . watching the screen I was afraid for a moment . . . that when they broke through the ice they might fall.”

“No danger of that.” She reached up and rotated the graphic 120 degrees. “Sometimes this is a helpful reminder, when up and down aren’t too significant.”

“You’re making fun of me, Jo,” Groves said disgustedly.

But a moment later he exclaimed “Oh!” in excitement and hope, for on the screen the ice mole had finally punc­tured the skin of Amalthea.

Unfortunately live visuals were missing: the mole’s orig­inal designers had not thought it sensible to put a camera on a machine that was meant to spend its working life sur­rounded by solid ice. “Blake. Professor. Can you see anything? Tell us what you see,” Walsh said.

Blake’s voice was delayed, coming over the comm. “Well, it’s kind of weird. We don’t have outside lights on this thing, but it doesn’t seem as dark. . . .”

“We’re in the water,” said Forster. “The lights of our cockpit are having a definite effect on the surroundings.”

“What are you talking about, sir?” came Blake’s puzzled voice over the commlink—

—as Walsh added her dry request, “Please be good enough to specify what the hell you’re referring to, Profes­sor.”

Forster’s voice came back to those who waited in the Ventris, satisfied and unmistakably thrilled. “Swarming all around us. Life. The water is full of it. . . .”


Lazy spirals of cable descended as slowly as smoke wreaths from the bulk of the Michael Ventris. Power cables and safety cables slithered across the ice toward the hole and disappeared into the vapor plume, following the mole inward. To Hawkins and McNeil, hovering nearby on the surface, the sign of the mole’s progress was a plume of ag­itated vapor in the mist.

They heard the reports from the mole over their suit­comms, and for a moment Hawkins shared the thrill of the impossible discovery. Life. For that moment, at least, he was able to stop thinking about Marianne Mitchell and Randolph Mays.