You may proceed to depth
, said the sub’s voice, and a tone sounded, indicating it was safe to descend. Blake pushed the controls forward. Instantly the school of fiery creatures peeled away, diving toward the bright nebulosity that lay at Amalthea’s center.
“I say, they’re doing it again,” Forster exclaimed. Again the school of squid appeared to be waiting for them, wheel-ing and darting at a constant depth almost a kilometer below. Forster’s voice was as excited as a boy’s. “Do you think they’re trying to communicate?”
Beneath them, the hot core had grown to the apparent size of the sun seen from Earth—too bright to look at di-rectly, without the viewport adjusted to filter the light. Streams of bright bubbles were flowing slowly away from Amalthea’s white core in serpentine columns, radiating symmetrically away from the region of maximum pressure, reaching steadily upward in every direction toward the moon’s surface.
Blake waited patiently, trying to imagine what was going through Forster’s mind. The professor had come tantaliz-ingly near the object of his decades-long search, but still it kept its distance, if only for a little while longer.
Forster listened to the sounds that came through the hull, broadcast on the sub’s sonar: the squeaky fizz of billions of pinpoint bubbles boiling off the hot core, the liquid slither and plash of bigger bubbles colliding and joining together. Almost overwhelming these inanimate sounds were the skir-ring and chittering of masses of animal life in this spaceborne aquarium, this vast dark globe of water rich in the nutrients of a terrestrial planet’s oceans.
The school of squid still waited below, swirling and div-ing and soaring and darting; the thousand wriggling crea-tures sang as they swam, in rhythmic birdlike chorus. Beneath the soprano choir a deep bass boomed with studied deliberation, like the slow ringing of a temple bell in the tropical night.
The first humans to see Io, in reconstructed video data sent back by
Voyager 1
, had called it a “pizza pie.” What would it have been called if those first observers had lived not on the outskirts of Los Angeles but in Moscow or Sao Paolo or Delhi?
Or seen it as Randolph Mays and Marianne Mitchell were seeing it now . . . ? The videoplate of their tin can capsule showed the fast-approaching moon in real time, at the same angular spread as if they’d been looking out the hatch with their own eyes. Io did not look much like a pizza pie to Marianne. It looked like hell frozen over; not counting the insides of various spaceships, it was the ugliest thing she had seen in her travels yet. But Io’s ugliness was so bold and wild, its elemental forces so immodestly displayed, that she found it almost arousing.
A voice she had learned to regard as background noise interrupted her thoughts: “Four active volcanos are visible from the current range and position of your Moon Cruiser, with plumes ranging from thirty to over two hundred kil-ometers in altitude. . . .”
Mays managed to keep his inner concentration even when the robot voice of the capsule chimed in with one of its periodic sightseeing lectures. He was like a Zen monk, sitting calmly, thinking nothing, knowing nothing but the incoming and outgoing of his breath.
“. . . the most easily visible in the lower right quadrant of your screen, near the terminator. Observe the umbrella-shaped plume of material, ejected from the vent at a velocity approaching one kilometer per second, more than a third of Io’s escape velocity. If you wish to see the larger globe of crystallized gases surrounding the volcano’s inner solid plume, tune your videoplate to the ultraviolet spectrum. . . .”
Now their capsule was approaching Io so fast that their movement toward it was perceptible. What had been a detailed and fascinating but still-distant landscape took on a new dimension; Marianne was reminded of her visit to the Grand Canyon on Earth, standing at an overlook, admiring distant vistas of buttes and mesas, when suddenly the gravel beneath her foot slipped and carried her a few inches toward the edge . . . .
The green line of their planned trajectory brought them to within three hundred kilometers of the surface of Io. At this scale the blue line of their actual track could have de-viated from the green line by no more than the width of a pixel or two, for it was still identical.
“We’re falling, you
might
say,” Mays conceded. “But we’re falling
past
the volcano, not into it. We’re falling past the surface of the moon. And then, of course, we’ll be falling toward Jupiter.” He enlarged the scale of the graphic swiftly—the familiar green ellipsoid was still there where it had been, looping around and eventually back toward Gan-ymede. “With any luck, we’ll miss
it
, too.” He smiled at her, and it was a smile with enough warmth in it to be what she needed, truly comforting.
She switched back to realtime. The picture was strikingly different. Gripped by Io’s gravity, they were falling now at 60,000 kilometers per hour, an astonishing speed this close to a fixed surface. Her facial muscles tightened, but she held her smile and made herself watch.
The volcano’s copious outpouring was as dark and as fluid as blood, a translucent mound of soft red spreading outward from the dark vent at its center in a symmetry that was almost voluptuous. Their capsule was a missile homing on the center of the plume’s creased pillow, which swelled as if to take them in. All around them rose soft mountains the color of flesh.
The voice of the capsule said, “Your Moon Cruiser’s vi-deoplate field of view is no longer selecting the surface of Io. If you wish to continue viewing Io, you may easily adjust your viewpoint by selecting ‘autotrack’ on your video console.”
“Randolph,” she said, in a voice that was low, almost angry, “can’t we get out of these stupid suits? I want you to hold me.” She didn’t wait for his answer before slapping at the clasps of her harness to free herself from her accel-eration couch.
She helped him catch up; then she continued with the rest of her clothes. Before long they were both tumbling naked in the feeble light of the screen, the dark and supple young woman, the hard-muscled, odd-angled, definitely older man.
In her urgency she paid no attention to the faint rumble of the capsule’s maneuvering system. Since she had done no homework, and currently had no interest in schematics, she had no way of knowing that the trajectory program had scheduled no course adjustment for this moment.
“It’s happening,” said Sparta. Ever since Mays and Mar-ianne had launched for Io, Sparta had haunted the firefly darkness of the AJE, the Space Board’s Automated Jupiter Environment traffic control center, whose green screens and trembling sensors tracked every craft in Jupiter space.
“
What
is happening, Inspector?” demanded a young German controller, her white-blond crew cut as square and shiny as the epaulets on her blue uniform. With audible contempt the controller said, “No alteration in the trajectory of the tourist canister is visible.”
Not to you, thought Sparta, but she said only, “While you’re watching and waiting, I’m putting our cutter on alert.”
Five minutes later the controller finally noticed a tiny discrepancy in the Moon Cruiser’s course, as yet within the limits of uncertainty of the tracking system; meanwhile Sparta took a call on her personal link.