The Diamond Moon (15 page)

When the little Moon Cruisers were running, an average circuit might last sixty hours or so, some two and a half days. What the tour operators didn’t emphasize was how very few minutes of this time would be spent in the near vicinity of any celestial body. The video player was stocked with an exciting selection of programs for all tastes, and the food and liquor cabinets were equally lavish. The personal hygiene facility at the back of the capsule offered the ulti-mate in robomassage. Or a passenger could select sleep mode, and with the aid of precisely measured drug injec-tions, skip the boring parts of the trip.

“Thirty seconds to launch,” said the voice. “Please lie back and relax. Have a good trip.”

 

Just as the video showed them about to enter the breech of the launcher, Mays reached up and tapped the plate’s selector switch.

“Hey,” Marianne protested. “The launch is the last exciting thing that’s going to happen to us for eighteen hours. We’ll have plenty of time to look at the map later.”
“That is not us on the screen, you know,” said Mays. “It’s
prerecorded
.” Mays was right. Where things could actually go wrong—however rarely—the tour operators thought it best to let the passengers see only a stage show, a shiny new capsule undergoing a perfect launch.

“I want to see the launch, not look at some stupid map,” she said heatedly. “Even if it’s only fake-live, at least it’s educational.”

“As you
wish
.” He flipped the channel back. Onscreen, the idealized launch capsule that might have been theirs, but wasn’t, was almost into the breech; electromagnetic coils were poised to seize it and hurl it forward. “Do you
mind
if I monitor the trajectory
after
we clear the rails? The map at least is generated in
real
time.”

“Whatever you wish, Randol . . .”

Their conversation was interrupted by the robot voice. “Ten seconds to launch. Please lie back and relax. Have a good trip. Nine seconds, eight, seven . . . just lie back and relax completely, your tour is about to begin . . . three, two, one.”

The acceleration didn’t hit like a fist, it came like a feather pillow laid across their tummies—a feather pillow that magically increased in weight, becoming first a sack of flour, then a sack of cement, then an ingot of cast iron. . . .

“Only thirty more seconds until our launch is completed. Just relax.”

Inside the capsule, the passengers lay smothered under ten gravities of acceleration. A row of diodes on their con-trol panel showed all green, but they would have been all green even in a dire emergency; the little green lights were window-dressing, intended to reassure passengers who were utterly helpless to affect their fate.

On the videoplate, the perfect prerecorded launch pro-ceeded. The capsule silently accelerated at a hundred meters more per second each second that ticked away, until it was moving far faster than a highpowered rifle bullet.

The coils of the launcher smeared into invisibility. Only the longitudinal rail that supported the coils could be seen, a single impossibly straight ribbon of shining metal vanish-ing somewhere above the distant horizon, into the stars.

They were weightless.

“Acceleration is complete,” the voice of the capsule reassured them. “Only five more seconds until our launch se-quence is over. Just continue to relax.”
Along the final few kilometers of the electric raceway the capsule drifted weightless at blurring speed, subjected to fine magnetic adjustments in aim and velocity—here each individual capsule had its trajectory tailored to fit its par-ticular destination, whether near-Ganymede parking orbit or distant moonscape fly-by.

Meanwhile the frozen surface of Ganymede curved away beneath the track, which in order to maintain its artificial Euclidian straightness now rose above the ice on spindly struts.

 

In an eyeblink it was over; the long launcher rail was behind them, and the ice mountains of Ganymede were fall-ing rapidly away. The screen was filled with stars.

 

“All right with you?” said Mays, not really asking her permission, as he tapped the channel over to “Itinerary.”

On the wide screen the scale of the graphic was set so as to fill the plate with the icy disk of Ganymede; a pale green line parallel to the equator extended from the far right side upward, and along it a bright blue line crept impercep-tibly. The green line was their planned route; the blue line was their actual track, as monitored by ground-based radar and navigation satellites. The two lines currently followed an identical trajectory for as far as they extended, and un-less something went terribly wrong, they would stay that way throughout the trip.

Mays adjusted the scale. The disk of Ganymede zoomed down to a tiny speck in the lower right portion of a screen filled with stars. The larger disk of Jupiter, realistically pat-terned with cloud bands, now dominated the center of the screen. Arranged around it in concentric rings were the orbits of Amalthea, Io, Europa, and Ganymede itself. Callisto lay farther out, offscreen. It was the poor sister of the Galilean moons, thought to be too like Ganymede to be worth a special trip; only when the moons were arranged so that the laws of celestial mechanics decreed it easier and quicker for a capsule to fly past Callisto than not were tourists able to judge Callisto’s charms for themselves.

The pale green line was a graceful loop of string that swooped inward past Io, curved steeply around Jupiter, came near Europa on its way back, and finally rejoined the orbit of Ganymede a third of the way farther along in its circuit. Amalthea was not on the itinerary; its orbit lay well inside the capsule’s closest approach to Jupiter.

Given the capsule’s energetic initial acceleration from Ganymede, most of the ride was coasting. But at certain key junctions, a nudge from the capsule’s strap-on rocket was necessary to get the roller coaster all the way around the curve.

Mays contemplated the graphics on the video plate, which at this scale changed too slowly to be perceived. The orange light of the false Jupiter was reflected in the face-plate of his spacesuit and lit a warm gleam in his eye.
Marianne yawned. “Maybe I’ll take the sleeper. Wake me when we get to Io.”

His reply was unnaturally delayed. “Delighted, my dear,” he murmured at last.

Something in the tone of his voice attracted her glance. “What are you scheming, Randolph?” she asked lazily, but the hypnotic was already running in her bloodstream, and she could not stay awake to hear his answer—

—which at any rate he did not give.
XV

The columns of white vapor that blew out of the crevices in the ice gave an illusion of great force, but there was nothing to them, only widely spaced water molecules mov-ing at great velocity under virtually no pressure. These most tenuous of winds had blown the huge alien antennas clear off into space; as the ice had dissolved from beneath their roots, the massive structures had drifted free and wafted away as lightly as if they’d been dandelion seeds on a sum-mer breeze. With them went the secret of their communi-cation with the stars—and with the core of their own moon.

Blake and Forster lay side by side in the Europan sub, Blake in the command pilot’s couch, skimming across the lacy ice. Hawkins and McNeil guided the sub by the tips of its wings. The pearly mist was so thick that light from their helmet lamps bounced back into their faces from a meter or two away.

Without a thread to guide them, they could have floun-dered for hours; they had to feel their way to the entrance shaft along the communications cables that hung like garlands in the mist. They found the opening of the shaft, a wider artificial blowhole in the featureless fog and ice, and the Old Mole tethered nearby, stationed there in case the shaft needed re-opening against the tendency of the boiling water down below to freeze over again.

“We’re ready to go in,” Blake said over the commlink.

 

“All right, then,” came back Walsh’s voice.

The launch was pure simplicity. Blake curled the submarine’s flexible wings around its body until the craft was smaller than the diameter of the shaft in the ice. Hawkins and McNeil positioned it above the opening and gently shoved it into the pressureless blowhole with the force of their suit-maneuvering systems.

The sub dived blind into the impenetrable fog. A hun-dred meters down, the surface of the water came up sud-denly, a vigorously boiling surface over which a steaming skin of ice constantly froze and broke apart and reformed.

Triggered by radar to ignite upon impact, the subma-rine’s rockets fired a brief burst to drive the buoyant craft below the surface that otherwise would have rejected it. The rockets continued firing, blowing out a stream of super-hot bubbles, until the free-swimming craft’s wings could unfurl and grab water. With strong strokes, the submarine swam swiftly down into the deep. Then it turned on its back and sought the undersurface of the ice. The water was murky with life—swarming, concentrated life.

“Hungry little devils.” Forster laughed, the happiest sound he’d made in months. “They’re exactly like krill. Swarms and swarms of them.” His bright eye had fixed upon one among the myriad swarming creatures fumbling against the polyglas, and he followed it closely as it wriggled help-lessly for a moment before orienting itself and darting away.
“Are they feeding?” Walsh’s voice came to them over the sonarlink.

“Yes, most of them,” Blake answered. “They’re feeding on the underside of the ice, on mats of purple stuff. An Earth biologist would call it algae . . . maybe we should call it exo-algae. And miniature medusas, clouds of them, are feeding on
them
.”

“We’ll have to let the exo-biologists sort it all out,” For-ster said. “I’ll get a few samples, Blake. But don’t let me take too long about it.”

 

“If you didn’t know we were inside one of Jupiter’s moons,” Blake said into the comm, “you’d think we were in the Arctic Ocean. And that it’s springtime.”

Forster and Blake were lying prone in the Europan submarine, nominally a two-person craft with just enough room for a third occupant to squeeze into the passage behind them. The Manta, they had nicknamed it, on the prin-ciple that if an old ice mole deserved a name, so did an old submarine—doing what the Old Mole couldn’t do, for the ice miner had served its main purpose as soon as it had cut its way into Amalthea’s interior.

The Manta was swimming upside down with respect to Amalthea’s center, its ventral surfaces skimming along only a meter from the rind of ice. The teeming biota of Amal-thea’s “arctic” seas—or at least a good and lively sample of it—was spread before them, brightly illuminated by the sub’s spotlights, separated from them only by the thin clear po-lyglas of the sub’s bubble. The white light was quickly diffused in water so thick with living particles—all of them eating or being eaten—that it resembled a thin broth. The darting, teeming schools of transparent krill were a shifting veil of rainbows in the beams of the floodlights.

The men in the sub used magnifying optics to examine the creatures on something closer to their own scale. The medusas were like many of the myriad species of jellyfish that swarm through all the seas of Earth, pulsing with strips of colored light. The creatures Forster called “krill” were shrimp-like, multilegged little beings with flat tails and hard transparent shells which left their pulsing circulatory systems visible. Whenever the submarine’s lights were di-rected toward them they swam frantically away— behavior that was easy enough to understand, given that a boiling “sun” was visible as a hot point of light many kilometers down in the murky depths and that the foodstuff of the krill lay in the opposite direction.

“What was that?” Blake said suddenly.

 

“
Ventris
, we have new visitors,” said Forster. “Something bigger than anything we’ve seen yet.”

“Looked like a squid,” said Blake. “There’s another . . . a bunch of them. I’m rolling the Manta.” The submarine flapped its wings and made a lazy half roll in the soupy water. The dark waters came alive with flickering, glowing life. Uncountable multi-tentacled, torpedo-shaped creatures danced in synchrony beneath them, none of them bigger than a human hand, but packed together in an immense school that darted and turned like a single organism. Each translucent, silvery animal was bright with turquoise beads of bioluminescence; together they formed a blue banner in the dark.

“They’re diving again,” Blake said.

 

“We’ll follow them,
Ventris
,” Forster said into the son-arlink. “I’ll worry about specimens later.”

 

Blake pushed the Manta’s diving controls forward and the sub put its transparent nose down. Flexible wings rippled, driving the craft deeper into darkness.

The Manta was a well-used sub, not as old as the Old Mole but based on vintage technology. Its passengers rested in an Earth-normal pressure regime of mixed oxygen and nitrogen. The sub carried liquid nitrogen in pressurized tanks and got its oxygen from the water, but while its oxygen-exchange mechanisms—its “gills”—were efficient enough at constant depths, the craft needed time to adjust internal working pressures to constantly changing external pressures.

And the pressures on little Amalthea, while they didn’t change as rapidly as they did on big Europa (or on bigger Earth), nevertheless mounted swiftly toward impressive numbers. At the surface, a person in a spacesuit weighed a gram or two, and the pressure was zero, a near-perfect vac-uum. At the moon’s core the same person would weigh nothing at all—but the pressure of the overlying column of water would have increased to several hundred thousand kilograms per square centimeter.

Blake, frustrated, couldn’t keep up with the rapidly de-scending school of exo-squid. The Manta’s alarm hooter went off before he’d descended four kilometers:
Do not attempt to exceed the present depth until the gill manifold has been recharged
, the sub’s pleasant but firm robot voice in-structed him.

Blake let the Manta level itself. They could do nothing but wait while the artificial enzyme mixture in the sub’s gill manifold was enriched. Outside the craft swam a menagerie of weird creatures, resembling several new species of luridly colored medusas and jellyfish and glassy ctenophores. A fish with a mouth bigger than its stomach drifted past, peering hungrily in at them with eyes as big as golf balls.