Captain Hew Mills, UN Space Arm, currently attached to the Solar System Exploration Program mission to the moons of Jupiter, stood gazing out of the transparent dome that surmounted the two-story Site Operations Control building. The building stood just clear of the ice, on a rocky knoll overlooking the untidy cluster of domes, vehicles, cabins, and storage tanks that went to make up the base he commanded. In the dim gray background around the base, indistinct shadows of rock buttresses and ice cliffs vanished and reappeared through the sullen, shifting vapors of the methane-ammonia haze. Despite his above-average psychological resilience and years of strict training, an involuntary shudder ran down his spine as he thought of the thin triple wall of the dome—all that separated him from this foreboding, poisonous, alien world, cold enough to freeze him as black as coal and as brittle as glass in seconds. Ganymede, largest of the moons of Jupiter, was, he thought, an awful place.
"Close-approach radars have locked on. Landing sequence is active. Estimated time to touchdown: three minutes, fifty seconds." The voice of the duty controller at one of the consoles behind Mills interrupted his broodings.
"Very good, Lieutenant," he acknowledged. "Do you have contact with Cameron?"
"There’s a channel open on screen three, sir."
Mills moved around in front of the auxiliary console. The screen showed an empty chair and behind it an interior view of the low-level control room. He pressed the call button, and after a few seconds the face of Lieutenant Cameron moved into the viewing angle.
"The brass are due in three minutes," Mills advised. "Everything okay?"
"Looking good, sir."
Mills resumed his position by the wall of the dome and noted with satisfaction the three tracked vehicles lurching into line to take up their reception positions. Minutes ticked by.
"Sixty seconds," the duty controller announced. "Descent profile normal. Should make visual contact any time now."
A patch of fog above the landing pads in the central area of the base darkened and slowly materialized into the blurred outline of a medium-haul surface transporter, sliding out of the murk, balanced on its exhausts with its landing legs already fully extended. As the transporter came to rest on one of the pads and its shock absorbers flexed to dispose of the remaining momentum, the reception vehicles began moving forward. Mills nodded to himself and left the dome via the stairs that led down to ground level.
Ten minutes later, the first reception vehicle halted outside the Operations Control building and an extending tube telescoped out to dock with its airlock. Major Stanislow, Colonel Peters, and a handful of aides walked through into the outer access chamber, where they were met by Mills and a few other officers. Mutual introductions were concluded, and without further preliminaries the party ascended to the first floor and proceeded through an elevated walkway into the adjacent dome, constructed over the head of number-three shalt. A labyrinth of stairs and walkways brought them eventually to number-three high-level airlock anteroom. A capsule was waiting beyond the airlock. For the next four minutes they plummeted down, down, deep into the ice crust of Ganymede.
They emerged through another airlock into number-three low-level anteroom. The air vibrated with the humming and throbbing of unseen machines. Beyond the anteroom, a short corridor brought them at last to the low-level control room. It was a maze of consoles and equipment cubicles, attended by perhaps a dozen operators, all intent on their tasks. One of the longer walls, constructed completely from glass, gave a panoramic view down over the workings in progress outside the control room. Lieutenant Cameron joined them as they lined up by the glass to take in the spectacle beyond.
They were looking out over the floor of an enormous cathedral, over nine hundred feet long and a hundred feet high, hewn and melted out of the solid ice. Its rough-formed walls glistened white and gray in the glare of countless arc lights. The floor was a litter of steel-mesh roadways, cranes, gantries, girders, pipes, tubes, and machinery of every description. The left-side wall, stretching away to the far end of the tunnel, carried a lattice of ladders, scaffolding, walkways, and cabins that extended up to the roof. All over the scene, scores of figures in ungainly heavy-duty spacesuits bustled about in a frenzy of activity, working in an atmosphere of pressurized argon to eliminate any risk of explosion from methane and the other gases released from the melted ice. But all eyes were fixed on the right-hand wall of the tunnel.
For almost the entire length, a huge, sweeping wall of smooth, black metal reared up from the floor and curved up and over, out of sight above their heads to be lost below the roof of the cavern. It was immense—just a part of something vast and cylindrical, lying on its side, the whole of which must have stretched far down into the ice below floor level. At the near end, outside the control room, a massive, curving wing flared out of the cylinder and spanned the cavern above their heads like a bridge, before disappearing into the ice high on the far left. At intervals along the base of the wall, where metal and ice met, a series of holes six feet or so across marked the ends of the network of pilot tunnels that had been driven all around and over and under the object.
It was far larger than a Vega. How long it had lain there, entombed beneath the timeless ice sheets of Ganymede, nobody knew. But the computations of field-vector resultants collected from the satellites had been right; there certainly had been something big down here—and it hadn’t been just ore deposits.
"Ma-an," breathed Stanislow, after staring for a long time. "So that’s it, huh?"
"That is big!" Peters added with a whistle. The aides echoed the sentiments dutifully.
Stanislow turned to Mills. "Ready for the big moment, then, Captain?"
"Yes, sir," Mills confirmed. He indicated a point about two hundred feet away where a group of figures was gathered close to the wall of the hull, surrounded by an assortment of equipment. Beside them a rectangular section of the skin about eight feet square had been cut away. "First entry point will be there— approximately amidships. The outer hull is double layered; both layers have been penetrated. Inside is an inner hull. . ." For the benefit of the visitors, he gestured toward a display positioned near the observation window showing the aperture in close-up.
"Preliminary drilling shows that it’s a single layer. The valves that you can see projecting from the inner hull were inserted to allow samples of the internal atmosphere to be taken before opening it up. Also, the cavity behind the access point has been argon-flooded."
Mills turned to Cameron before going on to describe further details of the operation. "Lieutenant, carry out a final check of communications links, please."
"Aye, aye, sir." Cameron walked back to the supervisory console at the end of the room and scanned the array of screens.
"Ice Hole to Subway. Come in, please."
The face of Commander Stracey, directing activities out near the hull, moved into view, encased in its helmet. "All checks completed and go," he reported. "Standing by, ready to proceed."
"Ice Hole to Pithead. Report transmission quality."
"All clear, vision and audio," responded the duty controller from the dome far above them.
"Ice Hole to Ganymede Main." Cameron addressed screen three, which showed Foster at Main Base, situated seven hundred miles away to the south.
"Clear."
"Ice Hole to Jupiter Four. Report, please."
"All channels clear and checking positive." The last acknowledgment came from the deputy mission director on screen four, speaking from his nerve center in the heart of the mile-long Jupiter Mission Four command ship, at that moment orbiting over two thousand miles up over Ganymede.
"All channels positive and ready to proceed, sir," Cameron called to Mills.
"Carry on, then, Lieutenant."
"Aye, aye, sir."
Cameron passed the order to Stracey, and out by the hull the ponderous figures lumbered into action, swinging forward a rockdrill supported from an overhead gantry. The group by the window watched in silence as the bit chewed relentlessly into the inner wall. Eventually the drill was swung back.
"Initial penetration complete," Stracey’s voice informed them. "Nothing visible inside."
An hour later, a pattern of holes adorned the exposed expanse of metal. When lights were shone through and a TV probe inserted, the screen showed snatches of a large compartment crammed with ducts and machinery. Shortly afterward, Stracey’s team began cutting out the panel with torches. Mills invited Peters and Stanislow to come and observe the operations first-hand. The trio left the control room, descended to the lower floor, and a few minutes later emerged, clad in spacesuits, through the airlock onto the tunnel floor. As they arrived at the aperture, the rectangle of metal was just being swung aside.
The spotlights confirmed the general impression obtained via the drill holes. When preliminary visual examinations were completed, two sergeants who had been standing by stepped forward. Communications lines were plugged into their backpacks and they were handed TV cameras trailing cables, flashlights, and a pouch of tools and accessories. At the same time, other members of the team were smoothing over the jagged edges of the hole with pads of adhesive plastic to prevent tearing of the lines. An extending aluminum ladder was lowered into the hole and secured. The first sergeant to enter turned about on the edge of the hole, carefully located the top rung with his feet, and inch by inch disappeared down into the chamber. When he had found a firm footing, the second followed.
For twenty minutes they clambered through the mechanical jungle, twisting and turning among the chaotic shadows cast by the lights pouring in through the hole above. Progress was slow; they had difficulty finding level surfaces to move on, since the ship appeared to be lying on its side. But foot by foot, the lines continued to snake sporadically down into the darkness. Eventually the sergeants stopped before the noseward bulkhead of the compartment. The screens outside showed their way barred by a door leading through to whatever lay forward; it was made of a steely-gray metal and looked solid. It was also about ten feet high by four wide. A long conference produced the decision that there was no alternative but for them to return to where the hole had been cut to collect drills, torches, and all the other gadgetry needed to go through the whole drilling, purging, argon-filling, and cutting routine all over again. From the look of the door, it could be a long job. Mills, Stanislow, and Peters went back to the control room, collected the remainder of their party, and went to the surface installations for lunch. They returned three hours later.
Behind the bulkhead was another machinery compartment, as confusing as the first but larger. This one had many doors leading from it—all closed. The two sergeants selected one at random in the ceiling above their heads, and while they were cutting through it, others descended into the first and second compartments to position rollers for minimizing the drag of their trailing cables, which was beginning to slow them down appreciably. When the door was cut, a second team relieved the first.
They used another ladder to climb up through the door and found themselves standing on what was supposed to be the wall of a long corridor running toward the nose of the ship. A succession of closed doors, beneath their feet and over their heads, passed across the screens outside. Over two hundred feet of cabling had disappeared into the original entry point.
"We’re just passing the fifth bulkhead since entering the corridor," the commentary on the audio channel informed the observers. "The walls are smooth, and appear to be metallic, but covered with a plastic material. It’s coming away in most places. The floor up one side is black and looks rubbery. There are lots of doors in both walls, all big like the first one. Some have. . ."
"Just a second, Joe," the voice of the speaker’s companion broke in. "Swing the big light down here . . . by your feet. See, the door you’re standing on slides to the side. It’s not closed all the way."
The screens showed a pair of standard-issue heavy-duty UNSA boots, standing on a metal panel in the middle of a pool of light. The boots shuffled to one side to reveal a black gap, about twelve inches wide, running down one side of the panel. They then stepped off the panel and onto the surrounding area as their owner evidently inspected the situation.
"You’re right," Joe’s voice announced at last. "Let’s see if it’ll budge."
There then followed a jumbled sequence of arms, legs, walls, ceilings, lightness, and darkness as TV cameras and lamps exchanged hands and were waved about. When a stable picture resulted, it showed two heavily clad arms braced across the gap.
Eventually:
"No dice. Stuck solid."
"How about the jack?"
"Yeah, maybe. Pass it down, willya?"
A long dialogue followed during which the jack was maneuvered into place and expanded. It slipped off. Muttered curses. Another try. And then:
"It’s moving! Come on, baby . . .—let’s have a bit more light I think it’ll go easy now. . .— See if you can get a foot against it.. ."
On the monitors the gray slab graunched gradually out of the picture. A black, bottomless pit fell away beneath.
"The door is about two-thirds open," a breathless voice resumed. "It’s gummed up there and won’t go any further. We’re gonna have a quick looksee around from up here, then we’ll have to come back to get another ladder. Can somebody have one ready at the door that leads up into this corridor?"
The camera closed in on the pitch-black oblong. A few seconds later a circle of light appeared in the scene, picking out part of the far wall. The light began moving around inside and the camera followed. Banks of what appeared to be electronic equipment. . . corners of cubicles . . . legs of furniture . . . sections of bulkhead. . . moved through the circle.
"There’s a lot of loose junk down at that end . . . Move the light around a bit . . ." Several colored cylinders in a heap, about the size of jelly jars . . . something like a braided belt, lying in a tangle . . . a small gray box with buttons on one face . . .
"What was that? Go over a bit, Jerry. . . No, a bit more to the left."
Something white. A bar of white.
"Jeez! Look at that! Jerry, will you look at that?"
The skull, grinning up out of the pool of eerie white light, startled even the watchers out in the tunnel. But it was the size of the skeleton that stunned them; no man had ever boasted a chest that compared with those massive hoops of bone. But besides that, even the most inexpert among the observers could see that whatever the occupants of this craft had been, they bore no resemblance to man.
The stream of data taken in by the cameras flashed back to preprocessors in the low-level control room, and from there via cable to the surface of Ganymede. After encoding by the computers in the Site Operations Control building, it was relayed by microwave repeaters seven hundred miles to Ganymede Main Base, restored to full strength, and redirected up to the orbiting command ship. Here, the message was fed into the message exchange and scheduling processor complex, transformed into high-power laser modulations, and slotted into the main outgoing signal beam to Earth. For over an hour the data streaked across the Solar System, covering 186,000 miles every second, until the sensors of the long-range relay beacon, standing in Solar orbit not many million miles outside that of Mars, fished it out of the void, a microscopic fraction of its original power. Retransmission from here found the Deep Space Link Station, lodged in Trojan equilibrium with Earth and Luna, and eventually a synchronous communications satellite hanging high over the central USA, which beamed it down to a ground station near San Antonio. A landline network completed the journey to UNSA Mission Control, Galveston, where the information was greedily consumed by the computers of Operational Command Headquarters.
The Jupiter Four command ship had taken eleven months to reach the giant planet. Within four hours of the event, the latest information to be gathered by the mission was safely lodged in the data banks of UN Space Arm.