The Aliens had apparently not only spotted all of the protected ships, but had concentrated their torpedo fire on them. The experiment was a complete failure!
There was no use in reminding Miles that he'd tried to warn him. Earth hadn't been able to heed such warnings. He handed the papers back, his mind tormented by a picture of seven hundred men—men probably like the guards who'd called him all right—who had lost their marginal chance to live because a robot had failed. It was nonsense, his mind told him. Soldiers were meant to die. But the picture remained.
"So what happens to me now?" he asked.
"You'll try again, of course," Miles answered, apparently surprised at the question. "At least the fact that they worked that hard to eliminate the ships with the screen indicates you're on the right track."
Norden stared at him despairfully. "It's like tracing a single drop of water in the ocean—or looking for a trace of life that can be detected for millions of miles when you're in the middle of hordes of living creatures. I've been working on that already. And the only reason wecoulddetect and screen the lizard signals was because they were unique.
"Hardwick was right about that, too. You have to look for life forces where they're scarce. I need isolation from people, animals—even from germs and viruses, probably."
Pat gestured to a map on the wall. "There are the mine installations on the other side of the Moon. Would they do?"
He had no idea, but it was the best he could hope for. He nodded slowly, and she turned towards the door.
"Then what are we waiting for?" she asked. "We've got too little time now."
"You're not going, Pat," he told her. "Nobody is. I need isolation from life, remember! Besides, if there's any means of communication between here and there, I'll need you here to work the communicator."
There was a television link that was still useful, as a quick check showed. And there were ships to carry as much equipment as he needed, including two rabbits, and a male and female sand lizard in little airtight cages where oxygen could be supplied from tanks. He had no idea of what he might need, and had to take everything he could imagine as being useful.
VI
Three hours later, he stood alone in the building that had served as a barracks for a mine crew. He watched the rockets leave, and began opening the airlocks to space. Any bacteria left by the former men would quickly perish, he felt sure. But he had to be thorough.
He had no hope of success yet. He might be keeping a death watch over the human race as the Aliens moved in—or a life watch, since he was seeking life while they were intent on ending it. But he, at least, was no living thing, and the life detectors of the Aliens should miss him. Somehow, he'd learn enough to seek vengeance among them.
They'd made a mistake in creating him with all the ability of the original William Norden, and the thinking speed of a robot. They'd made a bigger mistake in assuming that a robot was only a robot, and that orders in the form of compulsions would be followed without question.
For their mistakes, they'd pay. He had twenty-four hours out of each day for work, and, until they caught him, to learn their further weaknesses.
He flooded the front entrance, where the television link to Moon base stood, with air to make speech possible, and rigged up a flexible seal to the rest of the building.
Janiekowski had dissected countless sand lizards, and the pictures were included in the reel of tape from Earth. He studied them, digging into what the calculator had supplied about radiation, and its behavior in the third spectrum. He found, as he had expected, that a tiny bit of radio-active material lay at the base of the microscopic receptor in the female, and that a similar mechanism was to be found in the organ which the male used to generate the force.
There was a tiny helix of super-fine, wirelike construction around the radio-active material, but he had no idea of what the conductor was composed, or how the animals generated the faint currents of electricity they'd need. He was only sure the helix was a tiny electromagnet.
He built a model as best he could, and tried to find some indication that it picked up a signal from the male. Finally he was forced to anesthetize the female and remove her receptor for examination under the portable electron microscope.
It took eleven tries before he was able to detect anything of importance. Then the result surprised him. The faint, almost invisible glow from the radio-active disintegration in his device abruptly faded. He had been expecting it to increase, but whatever force the male broadcast seemingly acted to decrease the "unchangeable" rate of decay of a bit of K-40.
He called Pat, asking for information. Her face was haggard with worry, and her anxiety to remain constantly vigilant and alert. She wrote down his questions, and cut off without wasting time. Half an hour later, she called back.
"You're right. Uranium-bearing ores from far out in space contain much less uranium in proportion to lead than similar ores on Earth. Geologists say it's because those space-borne rocks are older, and cosmic radiation acts on them more continuously."
"They're wrong," he said flatly. "It's because radioactivity is inhibited by the life processes. I don't know how. But I do know I need that data fed into the computer."
It meant they'd have to revise all of their figures about the age of the Earth upwards. Since the beginning of life on Earth and Mars, no radio-active half-life had been natural. Probably the rate of decay had varied slightly with each century, as the amount of life changed.
He fed her a list of calculations, and waited while the machine ground out its answers. Pat came back to the screen while it worked on automatically.
"They're bombing the base now," she reported dully. "We've been able to miss being hit by keeping a cover of volunteers up to attract the seeking units before they reach us. And the Aliens are within three million miles. We can't hold out much longer."
"Don't forget your optimism," he said. He'd meant it for reassurance, but she stared back as if he'd slapped her. "I mean your computer calculations on victory for Earth. How come they moved in so quickly?"
"It's been three days," she told him. "Don't you know how long you've been out there?"
He hadn't kept track. The cluck of the computer ending its work interrupted them, and she held the results up to the screen for him to copy with the camera at his end.
He studied the formulae for long, wasted minutes before he could accept them. Then he went on to other work.
There was no shield possible for any object bigger than about twice the size of the cage they had used. There could never be any way to protect a man from the Aliens.
It was to be a death watch he kept, apparently. And Pat must have known it when she saw the formulae, since she had picked up sufficient basic knowledge to read it.
He stood staring up at the space above him, letting the hate harden inside him, while he pictured the base in the hands of the invaders! Humans were beyond saving, according to the figures he had now. But it was still not too late for vengeance.
This time he deliberately sought for a taboo in his mind to discourage thought along hindering lines. The forbidden topic was the question of why the Aliens had to exterminate life as they advanced. He wrestled with it briefly, rejoicing in the knowledge that he seemed to be gaining ease in overcoming the compulsory behavior which had been imposed on him.
Life must be poison to the Aliens! Probably it was for that reason that they had been able to detect it in the first place. And they could never rest until it was wiped out to the last living cell. He glanced at his formulae again, and nodded. If their existence were somehow based on the breakdown of radio-active isotopes, and if protoplasmic life slowed up that process, then theyhadto exterminate it.
How? He asked it automatically, remembering the force they used to sterilize space before them. And that had an answer, too. Even protoplasmic life apparently needed a tiny, incredibly small amount of radioactivity to function. Blast enough of the raw life-force against it, and all nuclear breakdown would stop—and with the stopping of that, there would be no life.
It was logical that the weapon of the Aliens should be the one thing which they themselves feared most.
Tiny—incredibly weak—as the energy of those life forces were, they could do more in their inhibiting of the great force of nuclear readjustment than ten million atomic bombs!
He drew up his plans this time with sureness. He was no longer amazed at the progress he'd made in understanding extraspectral phenomena. It might very well represent the work of generations of scientists, but he was a robot designed to understand human science, even from the few smatterings the Aliens had been able to learn before he had been created.
He finished the designs, wrote down the proper formulae, and stacked the paper in front of the television pick-up, pressing the call button. Without waiting for an answer, he went back into the workshop, and began assembling the tiny, radio-active strontium batteries and tubes of protein plastic, wound with layers of iron wire. He had enough for what he needed.
The device was set to work both as a detector and a generator of the radiation involved. He tuned one, setting it to receive. It took a few minutes to replace the antenna of the small radar set with the new device, and he forced himself to work faster by the sheer drive of his will.
Then he stepped aside, letting mechanism revolve on the antenna mount. He began increasing the current that controlled the degree of electromagnetism in the wire which served to tune the device.
A pip appeared on the screen, pointing toward the cage where the male and crippled female lay peacefully together. Norden raised the frequency until another pip appeared, this time pointing to the rabbits. He adjusted it for maximum brightness. In the section which should cover the direction of Moon base below him, a brilliant glow sprang up, indicating radiation that cut straight through all the layers of the Moon. He adjusted the instrument again.
He found the exact frequency, and the whole screen suddenly blazed, blanked out by overloading of the amplifier. Apparently all life of terrestrial origin radiated at the same frequency. He cranked up the control, expecting nothing more. Then he bent sharply forward as other pips appeared, indicating objects far out in space!
The Aliens also radiated in the same spectrum—but at such an incredibly high frequency that no atomic nucleus was small enough to be affected by the radiation.
As Norden watched, the central pip suddenly began to grow brighter, holding its position in a way that indicated a straight descent toward his detector! Terror struck at his nerves.
Obviously the Aliens had detectors for every frequency, and his detector was just crude enough to radiate a faint trace of its own. He'd been located, and the exterminating force was on the way.
VII
Norden cursed his own stupidity, and estimated the time it would take. If they decided to come in, and spray the area with their own force, or to capture it, he had several minutes. If they sent one of their super-speed torpedoes, he was on borrowed time. His mind raced furiously.
With a few minutes to spare, he could tune the tube he'd designed as a weapon, and spray them with that. Its straight-line efficiency would insure that no dangerous amount of its radiation would reach the men two thousand miles away. Vengeance was his for the taking.
He reached for the other tube, hesitated, and picked up a piece of paper and a pencil. The men at the base had the working plans of his device by now. They had to be warned how dangerous it would be not to make absolutely sure that their radiation generators and detectors couldn't spill dangerous radiation at random. Also that the Aliens could detect an inefficient search ray.
Norden headed for the flexible seal at a full run, while his steady hands pencilled the final information on the radiation frequencies needed. He broke through into the air of the entrance, yanked the diagrams off the pick-up rack, and snapped in the new instructions. He turned with a single motion, and headed for the workroom again. And stopped!
Beyond the entrance, the gleaming fins of a rocket were visible. And the red light on the airlock indicated someone was coming through. As his eyes focussed, he saw the inner lock open, and Miles and Pat emerged in the red glare.
They started to shout something, but he cut them off. "For God's sake, stay here. There's no air beyond. Alien ship!"
He jumped through the seal. His hands swept up the tube that was to be a weapon, and his eyes darted to the screen. The pip was bigger now, and at maximum brightness. The Alien ship must be only tens of thousands of miles above, braking down to attack with deadly precision.
Less than a hundred feet away, the two humans waited, at the mercy of any energy that might spill from his weapon! He would have to score with a perfect piece of marksmanship, with all the radiation directed in a straight line.
The formulae of its propagation seemed like an endless belt in his mind. He tightened the helix of wire about the radio-active lode, trying to be sure they were even. With time, there were a number of things he might have done, but he had no time to spare. He might harm Miles and Pat—but the Alien beam would leave nothing to chance.
The thought of Miles and Pat jolted through his mind in a delayed reaction. They'd seen him come into this airless space without a helmet. They knew now he wasn't human! Discovered!Explode the ...
"No!" he shouted silently into the airless room. He had to get the Alien first!
He had no idea how much time he had left as he snapped a flashlight battery into place, and tried to line the weapon into resonance with the detector settings. He lifted his eyes, to stare up through the open roof of the building. He knew there should be a faint black dot in the sky, but he couldn't see it against the blackness of space.
He lifted the weapon, pointed it toward where the Aliens should be, and depressed the little trigger, moving the rheostat back and forth to be sure he had the lethal frequency well covered.
He felt a tremor on the floor beside him, and his eyes caught a glimpse of Pat at his side before he could force his gaze toward space again. She was shouting something inside her helmet.
Then he caught the first visible sign of the Alien ship, already within miles of the building, and big enough to show in the side-light of the sun. It came rushing down in an unchecked plunge, apparently heading straight for him! He strained his eyes, tracing its path. Then he relaxed. It was moving sideways and would land a mile away.The weapon had worked.No ship would have risked such speed so near the surface if the pilot had been alive.
He gripped Pat by the shoulder, and dragged her to the floor, away from the threat of falling debris. There was no sound, but a tremendous jolt rocked the floor of the building, and for a terror-fraught moment the ground seemed to dance madly. A shaft of greenish-yellow radiance merged with a glaring red that lit up the sky for miles. The ship had struck at a terrific speed—fast enough to reduce everything inside it to a pulp. The instant everything was quiet, Norden sprang to his feet.
Now! There is no time to be lost!
He caught the thought in time. He couldn't let himself explode in the workroom. He had to get outside, away from the two humans. The compulsion squeezed and writhed in his mind, and he could not throw it off. It was tenfold as strong as the previous commands—and the need to overcome it a hundred times as great.
He stumbled toward the seal as Pat stood by. His body slipped through the seal, and he almost bumped into Miles, who was apparently waiting for him. Norden had no spare effort for speech or thought. He headed dumbly for the airlock, determined to get outside as quickly as possible.
"Norden!" The general had grabbed his arm, and was following him. "Norden, if you go out there, I'm going with you. Whatever happens will happen to me, too.You've got to listen!"
He tried to force his way ahead, shaking his arm to free it. The other arm was also carrying a dead weight, and he could see Pat's face close to his own.
She was screaming at him. "Bill! Bill, you must listen! We knew it all along! Weknewyou were a robot! It doesn't matter. If you explode, you'll take us with you!"
He hit the lock in savage desperation and the words froze meaninglessly in his ears as he held back the driving urge until he could escape from them.
Miles clung grimly. "It's the Aliens, Bill! They want you to explode. The damned Aliens who want to kill you! Do you love them so much you'll kill us all? Or do you hate them?"
Slowly it penetrated the red haze of torment in his mind. The Aliens wanted to kill him. They'd played with him, had turned him into a monster to do their malicious bidding. They'd given him nothing in return. And now they wanted everything. His own life, worthless though it might be—and the life of his friends.
The hate washed through him—the cold, hard hate that had a greater strength for its very lack of endocrine instability.
"I'm all right," he said slowly. "You're safe. You can go back to the base."
Miles stared at him with a warm and friendly understanding. "We really did know about you, Bill," he said. "That business about your being the only undetected human on the asteroid looked suspicious, and the psychologists weren't fooled. We were gambling on a chance to get some information on the Aliens' detector out of you before you could do anything dangerous.
"Hardwick was the only man who could have known enough to have any chance. With him dead, we had to hope they'd give you information enough to act in his place. Pat volunteered to watch you. And we had ultra-violet cameras in every room where you ever were, watching you every second."
He paused, but Norden could think of nothing to say. He looked at Pat for confirmation, and she nodded. "We set the whole thing up for you, Bill. But we found we were wrong. The Aliens had done too good a job on you for their own good. They made you too human—so human that you had to begin thinkingourway. After that business with Armsworth, we stopped worrying."
"But you came out here ..." he began.
"Not to spy on you, Bill," Miles told him. "Earth's evacuating the Moon, now that you found us weapons to handle the Aliens. We're needed to supervise things back at the factories. Pat and I just came to pick you up, when you wouldn't answer your calls. We're taking you home."
He stared at them silently, and there was a complex of feelings in his mind that made thinking almost impossible. Bitterness was heavier than anything else.
"That's fine for someone who won't hate an enemy—though you're quick enough to employ hate when it's useful." He looked at Miles steadily. "What about the rest of the world? Will they welcome a bomb-carrying robot monster as a friend?" Bill Norden wanted to know.
Miles put his hands on Norden's shoulders, while Pat went back into the workroom. "Sit down on the desk, Bill," he urged. "The only people who know are the two of us, and Jim—the psychologist who predicted exactly how you'd react from the beginning. He also gave you a test that first day that involved our top-grade X-ray machine—not one of those fluoroscopic toys. It's a good thing you've got your brains all through you, because when I get done, you'll be literally empty-headed."
Pat came back with a collection of equipment. Norden stared, trying to sit up. "You must be insane. Do you want to be killed if I blow. Are all humans crazy?"
Miles tightened his grip on Norden's shoulder. "Hold still. It shouldn't hurt. We're going to leave the communication gadget where it is, as it may be useful, later. But that bomb must come out." He smiled abruptly. "As to humans—well, you should know."
VIII
Three days later Bill Norden took his hands from the back of his neck, and sat up. He joined Miles and Pat at the screen of the big life-force "radar." Far out in space, a group of swiftly moving objects were drawing together, according to the pips that traced their course. They formed into clusters and began heading outwards.
The pips grew dimmer almost instantly, though they should have lost only half their brightness after a billion miles of traveling.
"Obviously faster than light, and heading straight toward Sirius," Miles said slowly. "The poor devils! Until some darned fool from Earth goes there one day to try to make peace with them, they're going to live every hour of their lives in the horrible certainty that we can wipe them out whenever we choose—and that the best their race could do was a total failure. They'll probably have sunk back to being scared, unhappy savages before we reach them."
Norden thought of the charts that had been shown him while he lay in the communicating position. Earth had enough life-force projectors to sweep the skies with lethal radiation already, and she had just begun to tool up.
The Aliens had guessed wrongly about every step—they'd followed a logical pattern against a race that defied logic.
And somehow, his hatred of them was gone. "You'll have the superlight drive next year, probably," he guessed. "There are enough of their ships out there now with Aliens who died before they could set off their bombs for you to figure that out. Earth will be sending a ship there before they can revert to complete savagery."
"And I suppose you want to be on it?" Pat asked. She looked at her father, smiling thoughtfully as he grinned in answer to her lifted eyebrow. "I imagine the three of us could swing permission, at that."
Norden nodded. He'd planned it all out. He'd have to go back to university work, pretending to explore the new trails of science that had opened with the discovery of Hardwick's spectrum. The formulae he'd developed had been destroyed, but he could always remember enough to keep up with the eager young men who would go plunging into the field.
Maybe, that way, by the time the probable levels of telepathy and other psi-phenomenon had been discovered, the world would be ready for them. He had no intention of acting as a super-brain, however well equipped he might be. With the emergency over, the human race could discover enough by itself.
Miles and his daughter would be busy with the long and difficult job of trying to re-settle the planets that the Aliens had despoiled. But all three of them would be ready when the first ship capable of reaching the stars had been built.
Norden drew himself up.
"Yes," he said. "Yes, I guess I want to be on it. I helped teach the Aliens enough about human beings as enemies. Now I'd like to teach them about us as friends."