"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.