by Isaac Asimov
Before he dressed, he searched his body for clues to who he was. He found no scars large enough that he would expect to remember when and how he acquired them. He bore no tattoos or skin ornaments, wore no rings or jewelry.
The only distinctive mark he seemed to bear was inside, in the things that he knew. Somewhere, sometime, he had received advanced training in microelectronics. He had more than a passing understanding of robotics and computers. Was that commonplace, a standard curriculum for someone his age? He thought not. And if not, it might be the trail that he could follow to rediscover himself.
The com center was continuing its intransigence, still ignoring his input, still mockingly displaying the words MESSAGE TRANSMITTED. But there was one door that hadn’t yet been slammed in his face. Donning a breather and a spare cartridge pack, Derec left the E-cell to explore the rest of the complex.
Derec began by creating a mental map of the great chamber, assigning arbitrary compass points with the E-cell as his reference for south. The chamber seemed to be roughly rectangular, longer north to south than east to west by a factor of two or more. He started hand-walking northward down the same corridor the custodian robots had used, counting his paces as he went.
Five hundred paces later, his arms were tired and the north wall seemed no closer. Stopping to rest, he surveyed the robot population of the chamber. He tallied seventeen of the humanoid robots, none of which were nearby. Among the nonhumanoid robots, he identified five different types: the pickers, the custodians, a large cargo handler Derec dubbed a porter, some multi-armed micro-assemblers, and an armored robot with oversized grapples whose function he could not guess.
Most of the robots he encountered were moving purposefully through the aisles, carrying out their assignments. But toward the north end of the chamber, Derec spotted a small army of robots standing inert and deenergized, waiting to be called into action. All the varieties were represented among the reserves except for the humanoid robots.
The robot stockpile was Derec’s clue to understanding where he was. The chamber seemed to be primarily a collection of spare parts. True, he had spotted a cluster of injection and extrusion machines in one area, a battery of laser welders in another, a chip-burning shop in a third, all apparently in full-time use. But all those operations were apparently maintenance related.
Whatever they’re doing here, they’re on a very heavy duty cycle — possibly even continuous operations, he told himself. Zero down-time could only be bought with a large-scale repair and maintenance operation. And that high price was only worth paying when time mattered more than money.
There was a steady stream of robot traffic on the lifts located at intervals through the chamber, and the obvious next step was to find out where they were going. Giving up his plan to walk the length of the chamber, Derec headed for the nearest lift.
Like the breather, the lifts were clearly the product of a unique approach to engineering. To Derec, they looked like something either unfinished or nonfunctional. They were also more proof that the complex had been designed with robots alone in mind. No human would have ridden one voluntarily.
The shaft was a vertical boring three meters in diameter, its sides lined with the same synthemesh as the chamber ceiling. Peering out over the edge and down, Derec glimpsed a deep shaft lit at regular intervals by stationary blue glows, which he assumed marked other levels. The shaft seemed to extend much farther down than up. Above the great chamber — which he had begun to think of as the warehouse — he counted only seven levels, while below it he could see at least twenty levels before the traffic in the shaft obscured what might lie beyond.
A descending lift platform on the nearest guide rod obliged Derec to duck back out of the way. The platform, a square grid a meter on a side, reached the floor level and stopped as though waiting for him.
While it waited there, traffic kept moving on the other three guide rods. Watching the robots board and disembark, Derec saw that while the lift was in operation, the robots were clamped to the platforms magnetically. He wondered how he would be able to keep his balance and footing without that assistance. There were no railings to grab on to, and the guide rod itself appeared to be electrically live.
Personal considerations aside, he could not help but admire the engineering aesthetics of the lift. It was a clean and focused solution to the problem of moving the maximum amount of traffic in the minimum time and space, a solution fully integrated with the requirements of the colony.
But clever as the system was, Derec was not eager for a ride in the dark on an open platform above a seemingly bottomless pit. Still, it was that or go back to the E-cell. He swallowed hard once and stepped carefully out onto the waiting platform.
“Up,” he said.
“Level, please?”
“Uh — Level Two.”
Singing a high-pitched song, the car began to climb swiftly. He stood with his arms crossed over his chest and his legs spread wide. Keeping his vision focused upward toward the nearest of the blue glows, he tried not to look at the shaft walls sliding swiftly by.
The platform flashed through several other levels before gradually slowing to let him off. The glimpses he caught of them prepared him for what awaited him on Two. When he stepped off the lift, he was standing at the crossroads of two low-ceilinged tunnels, each six meters wide. The walls, floor and ceiling were covered with the ubiquitous off-white synthemesh. The air was colder than ever, cold enough to make him hunch his shoulders and bury his hands under his arms.
Though the immediate vicinity of the lift was brightly lit by the blue floodlights, the tunnels themselves were illuminated only by dim yellow lamps set at intervals in the ceiling. Each was barely bright enough to mark its own position and make a tiny pool of yellow light on the floor of the tunnel.
The distant ends of the intersecting tunnels were invisible, the lines of ceiling lamps receding into infinity in both directions. The tunnels could be kilometers long, even tens of kilometers for all he could tell.
Have they honeycombed this entire asteroid? Derec wondered. Thousands of levels — shafts a hundred kilometers deep — could this be a mining operation?
But he could not understand why anyone would go to the trouble to mine an asteroid from the inside. The cutters on a prospecting ship could slice all but the densest nickel-iron asteroids into bite-sized chunks for the leviathan processing centers. No ore Derec knew of was worth the expense of tunnel-and-shaft mining on this scale. Even with the energy-and-raw-materials economics which applied with robot labor, it would have to be something a hundred times more precious than the rarest element — unless the value of secrecy was part of the equation.
Who am I dealing with? Derec wondered. Newly sobered, he stepped back onto the lift.
“Level Three,” he said.
The next two levels were just as silent and finished-looking as Two. Derec could not decide whether they were finished-waiting-to-be-used, like the spare parts in the great chamber, or finished-and-abandoned.
But Level Five was another story. The rumble of heavy machinery assaulted his ears even before the platform reached the lighted zone. When he stepped off the lift, he could feel rolling, low-frequency vibrations in the floor and ceiling of the tunnel.
I’m getting closer, he thought. Now — which way? The sound surrounded him, offering no clue as to which of the tunnels had the most promise.
While he stood there equivocating, a double platform arrived and disgorged a porter robot. On impulse, Derec climbed onto its half-full cargo pad. He was counting on its ignoring him, as the picker had. He was not disappointed. Neither cradling him in its arms nor trying to dislodge him, the porter started down the south tunnel.
For the first two minutes of the ride, wind noise and the whine of the robot’s own mechanisms masked the distant work noise. But before long Derec could sort the separate elements: irregular thumping sounds like muffled explosions, a highpitched grinding that made his skin crawl, and a steady backgr
ound rumble that suggested great masses of rock and ice being moved about.
Presently the end of the tunnel came in sight as a black patch in the distance. Shortly after, Derec began to detect a whiff of ammonia in the air. The moment he did, another piece of the puzzle fell into place.
He had wondered from the start why the complex outside the E-cell was filled with nitrogen. The robots did not require it. Strictly speaking, robots did not require an atmosphere at all. And keeping the complex sealed and pressurized had to be more complicated than simply opening it to space.
But maintaining a standard two-gas atmosphere in the proper proportions through the vast complex was even more complicated. Derec had concluded that the nitrogen atmosphere and “open” breathers were a compromise between the inconvenience of full pressure suits and the complexity of a dual-gas E-system. The nitrogen allowed humans to speak and hear normally and to move about without safesuits, without the fire and explosion risk posed by free oxygen.
But Derec had overlooked something important. The ices which made up a large fraction of the asteroid’s bulk were not water, but compounds like methane and ammonia. The mining processes would inevitably release them as gases into the work area, where they might react with the high energies and circuits of the mining machinery or with each other.
I should have seen it sooner, he thought. Without an atmosphere comprised of some relatively inert gas, there would be no way to dilute the unwelcome compounds or efficiently flush them out. So of course, an atmosphere. Of course, nitrogen. The atmosphere accommodated a human presence, but was not primarily for human convenience.
The porter slowed as they neared the end of the tunnel, and Derec took that opportunity to jump off. Ahead of him were several robots, gathered near the end of the tunnel, and the gateway to what he presumed was the work chamber. Through the gateway he caught glimpses of a ragged rock wall, equipment booms, and an occasional flash of bright light.
The gateway itself was an enormous boxlike machine which filled the tunnel flush to the walls, floor, and ceiling. The only path through to the work chamber was a narrow walkway between columns of bright green chemical storage tanks. That was where he had to go.
As Derec drew closer, he saw that the gateway was actually crawling slowly forward. Like some mechanical larva, the gateway was burrowing through the asteroidal mass and leaving a finished tunnel in its wake. Everything — the raw material of the walls, the covering of reinforcing synthemesh, even the overhead lamps — was being handled in one continuous operation. The gateway was a four-surface paving machine.
But Derec’s real interest was in the excavation beyond. He stepped up onto the gateway and threaded his way between the shoulder-high cylinders, aware as he did that one of the humanoid robots was following him. There was a strong draft through the walkway, from the tunnel to the chamber beyond. Even so, the odor of ammonia was almost strong enough to make him gag.
At the forward end, the narrow walkway widened into a control cabin, where two humanoid robots sat behind a bank of transparent panels looking out into the excavation chamber that surrounded the gateway on three sides. Derec stopped a few steps short of the ramp into the excavation and tried to sort out the functions of the equipment that filled it.
The uncut face of the asteroidal material was some thirty meters away. A two-headed boom cutter was working it, one boom bearing rotary grinders, the other microwave lasers. They moved back and forth like weaving cobras, and the ice and rock wall crumbled before them.
The lasers seemed to be doing most of the damage. Suddenly released from its icy glue, loose rock sloughed off the face with a cracking sound. More resistant deposits were gouged off by the rotating teeth of the grinder. The gases boiling off the face were being sucked into the wide-mouthed exhaust vents that loomed over the work face.
As he studied the work rig, a metallic hand touched his shoulder.
“You may not enter the processing zone during operations,” the robot said.
The robot’s edict stirred a flash of annoyance. “I will if I want to,” Derec snapped back over his shoulder.
The robot tightened its grip pointedly. “You may not enter the processing zone during operations,” the robot repeated. “Untrained personnel are to be considered at risk.”
Shrugging off its touch, Derec turned his back on the robot and looked once more into the excavation. Like the gateway, the mining unit was slowly advancing toward an ever-receding rock face. The motion brought the jumble of loose rock within reach of scuttling scooper arms, which funneled it up a ramp to an enormous hopper. A pair of high-sided conveyors carried material away from the hopper, one to the left and one to the right. While on the conveyor it passed through an N-ray station, an X-ray station, and a magnetometer.
From that point on, things got confusing. It was as though after having gone to all that trouble to mine the asteroid, the robots had forgotten to sort out the part of it they wanted to keep.
Some of the tailings were diverted to a spur conveyor, run through a crusher, and then used as the raw material for the fifteen-centimeter thick walls of the tunnel. To Derec’s astonishment, the rest was carried to the back wall of the work chamber, reunited with the captured methane and ammonia, and built up into a wall of ice and rock again. The excavation never got any larger.
But what about the tunnel? Derec wondered. They have to be taking something out —
Closer study showed him otherwise. The empty volume of the ever-lengthening access tunnel meant only that the asteroidal material surrounding it was being replaced in a more compressed state than it was in when mined. Nothing was being extracted. Nothing was being carried away for later refining or shipment.
It just didn’t make sense.
The depletion alarm on Derec’s first cartridge pack began to sound, and he transferred the delivery tube to the backup. He would have to leave soon or risk dying of nitrogen poisoning before he could return to the E-cell. But it was hard to tear himself away from the incomprehensible sight of a dozen robots and a few million dollars worth of heavy equipment engaged in a task as senseless as trying to dig a hole in water. And how many other excavations just like this were underway elsewhere in the complex? Ten? Fifty? Five hundred?
Trying to understand, Derec focused his attention on the robots. Three of the armored type patrolled the hopper, breaking up snags with their grapples. A fourth stood on a small platform under the booms of the cutter, shattering oversized rocks as they fell from the face with blasts from its chest-mounted laser. Two humanoids stood at the N-ray stations, intently studying the scanning screen.
Derec’s guardian angel was still standing within arm’s reach behind him, and he turned and sought the robot’s eyes. “What are you mining here?” he demanded. “What’s the point of all this?”
But the robot said nothing, gazing back with its expressionless eyes.
“Get out of the way,” Derec said disgustedly, and the robot stepped aside into the control booth to let him pass.
His annoyance spilling over into anger, Derec stalked down the narrow walkway and jumped down to the tunnel. It was then he realized his mistake: there were no porter robots there to carry him back to the lift.
“I need a ride,” Derec said sharply to the nearest humanoid robot. “Can you tell me when the next porter robot will be making a delivery?”
“What is your need?”
“I need a ride.”
“That is not an approved allocation of resources.”
Derec did not even bother to argue. Turning away, he stalked away northward, his mind unsettled, churning with unconnected thoughts. He felt as though the answer to all his questions was already in his grasp, except he couldn’t recognize it. How did it all add up? What was wrong with the picture?
As he hand-walked along the tunnel, his thoughts kept carrying him back to the robots. There was something about the way they behaved, the way they worked together. Throughout the complex, all the routine, repetitive
jobs were being done by the nonhumanoid robots. The blue-skinned humanoid robots were supervisors, trouble-shooters, technicians, repair specialists. But they could have just as easily done the repetitive jobs as well, even tending the front line in the excavation. Instead, there were a half-dozen specialized varieties, porters and pickers and miners that didn’t act like robots at all —
Derec stopped short and turned to stare back down the tunnel toward the excavation. Of course. Of course. The picker and the custodians, the tenders and the porters weren’t specialized robots working with the blue robots. They were tools being used by the blue robots. Their intelligence was limited — perhaps not even positronic in nature. The real intelligence resided in the humanoid robots, which might well be more sophisticated than any Derec had previously known of.
But why were they all here?
Derec thought of all the levels, all the tunnels that had already been bored out, all the mass of the asteroid still waiting undisturbed. Could he have stumbled on an industrial test site? It might explain much — the secrecy, the distinctive stamp of the unknown designer, the unending but pointless excavation.
Focus on the robots, Derec told himself. The tasks they’re handling themselves are the ones they consider critical —
In a flash of memory, he saw the two humanoid robots tending the scanning instruments on the conveyor line, and suddenly Derec knew. The realization staggered him, and yet there was no pushing the notion away once it had formed in his mind.
The robots weren’t mining the asteroid at all. They were sifting it. They were searching for something, something lost or buried or hidden, something so unique and valuable that it was worth any price, any effort.
What that something was, Derec could not imagine. And just at that moment, he was not sure that he ever wanted to find out.
Chapter 4
YOU CAN’T GET THERE FROM HERE
