Chapter 10

That was it! Somebody was devising ingenious ways to get well-known destructive devices into places where they did not belong, but where they would be effective. Rockets. Bombs. Even radioactive cobalt dust. All were perfectly well-known means of destruction. The minds that planned those tricks said, in effect: "These things will destroy. How can we get them to where they will destroy something?" It was a strict pattern.

But the pushpot sabotage--and Joe was sure it was nothing else--was not that sort of thing. Making motors explode.... Motors don't explode. One couldn't put bombs in them. There wasn't room. The explosions Joe had seen looked as if they'd centered in the fire basket--technically the combustion area--behind the compressor and before the drive vanes. A jet motor whirled. Its front vanes compressed air, and a flame burned furiously in the compressed air, which swelled enormously and poured out past other vanes that took power from it to drive the compressor. The excess of blast poured out astern in a blue-white flame, driving the ship.

But one couldn't put a bomb in a fire basket. The temperature would melt anything but the refractory alloys of which a jet motor has to be built. A bomb placed there would explode the instant a motor was started. It couldn't resist until the pushpot took off. It couldn't....

This was a different kind of sabotage. There was a different mind at work.

In the afternoon Joe watched the landings, while the young lieutenant followed him patiently about. A pushpot landing was quite unlike the landing of any other air-borne thing. It came flying down with incredible clumsiness, making an uproar out of all proportion to its landing speed. Pushpots came in with their tail ends low, crudely and cruelly clumsy in their handling. They had no wings or fins. They had to be balanced by their jet blasts. They had to be steered the same way. When a jet motor conked out there was no control. The pushpot fell.

He carefully watched one landing now. It came down low, and swung in toward the field, and seemed to reach its stern down tentatively to slide on the earth, and the flame of its exhaust scorched the field, and it hesitated, pointing up at an ever steeper angle--and it touched and its nose tilted forward--and leaped up as the jet roared more loudly, and then touched again....

The goal was for pushpots to touch ground finally with the whole weight of the flying monstrosity supported by the vertical thrust of the jet, and while it was moving forward at the lowest possible rate of speed. When that goal was achieved, they flopped solidly flat, slid a few feet on their metal bellies, and lay still. Some hit hard and tried to dig into the earth with their blunt noses. Joe finally saw one touch with no forward speed at all. It seemed to try to settle down vertically, as a rocket takes off. That one fell over backward and wallowed with its belly plates in the air before it rolled over on its side and rocked there.

The last of a flight touched down and flopped, and the memory of the wreckage had been overlaid by these other sights and Joe could think of his next meal without aversion. When it was evening-mess time he went doggedly back to the mess hall. There was a sort of itchy feeling in his mind. He knew something he didn't know he knew. There was something in his memory that he couldn't recall.

Talley and Walton were again at mess. Joe went to their table. Talley looked at him inquiringly.

"Yes, I saw both crashes," said Joe gloomily, "and I didn't want any lunch. It was sabotage, though. Only it was different in kind--it was different in principle--from the other tricks. But I can't figure out what it is!"

"Mmmmmm," said Talley, amiably. "You'd learn something if you could talk to the Resistance fighters and saboteurs in Europe. The Poles were wonderful at it! They had one chap who could get at the tank cars that took aviation gasoline from the refinery to the various Nazi airfields. He used to dump some chemical compound--just a tiny bit--into each carload of gas. It looked all right, smelled all right, and worked all right. But at odd moments Hitler's planes would crash. The valves would stick and the engine'd conk out."

Joe stared at him. And it was just as simple as that. He saw.

"The Nazis lost a lot of planes that way," said Talley. "Those that didn't crash from stuck valves in flight--they had to have their valves reground. Lost flying time. Wonderful! And when the Nazis did uncover the trick, they had to re-refine every drop of aviation gas they had!"

Joe said: "That's it!"

"That's it? And _it_ is what?"

Then Joe said disgustedly: "Surely! It's the trick of loading CO_2 bottles with explosive gas, too! Excuse me!"

He got up from the table and hurried out. He found a phone booth and got the Shed, and then the security office, and at long last Major Holt. The Major's tone was curt.

"Yes?... Joe?... The three men from the affair of the lake were tracked this morning. When they were cornered they tried to fight. I am afraid we'll get no information from them, if that's what you wanted to know."

The Major's manner seemed to disapprove of Joe as expressing curiosity. His words meant, of course, that the three would-be murderers had been fatally shot.

Joe said carefully: "That wasn't what I called about, sir. I think I've found out something about the pushpots. How they're made to crash. But my hunch needs to be checked."

The Major said briefly: "Tell me."

Joe said: "All the tricks but one, that were used on the plane I came on, were the same kind of trick. They were all arrangements for getting regular destructive items--bombs or rockets or whatever--where they could explode and smash things. The saboteurs were adding destructive items to various states of things. But there was one trick that was different."

"Yes?" said the Major, on the telephone.

"Putting explosive gas in the CO_2 bottles," said Joe painstakingly, "wasn't adding a new gadget to a situation. It was changing something that was already there. The saboteurs took something that belonged in a plane and changed it. They did not put something new into a plane--or a situation--that didn't belong there. It was a special kind of thinking. You see, sir?"

The Major, to do him justice, had the gift of listening. He waited.

"The pushpots," said Joe, very carefully, "naturally have their fuel stored in different tanks in different places, as airplanes do. The pilots switch on one tank or another just like plane pilots. In the underground storage and fueling pits, where all the fuel for the pushpots is kept in bulk, there are different tanks too. Naturally! At the fuel pump, the attendant can draw on any of those underground tanks he chooses."

The Major said curtly: "Obviously! What of it?"

"The pushpot motors explode," said Joe. "And they shouldn't. No bomb could be gotten into them without going off the instant they started, and they don't blow that way. I make a guess, sir, that one of the underground storage tanks--just one--contains doctored fuel. I'm guessing that as separate tanks in a pushpot are filled up, one by one, _one_ is filled from a particular underground storage tank that contains doctored fuel. The rest will have normal fuel. And the pushpot is going to crash when that tank, and only that tank, is used!"

Major Holt was very silent.

"You see, sir?" said Joe uneasily. "The pushpots could be fueled a hundred times over with perfectly good fuel, and then one tank in one of them would explode when drawn on. There'd be no pattern in the explosions...."

Major Holt said coldly: "Of course I see! It would need only one tank of doctored fuel to be delivered to the airfield, and it need not be used for weeks. And there would be no trace in the wreckage, after the fire! You are telling me there is one underground storage tank in which the fuel is highly explosive. It is plausible. I will have it checked immediately."

He hung up, and Joe went back to his meal. He felt uneasy. There couldn't be any way to make a jet motor explode unless you fed it explosive fuel. Then there couldn't be any way to stop it. And then--after the wreck had burned--there couldn't be any way to prove it was really sabotage. But the feeling of having reported only a guess was not too satisfying. Joe ate gloomily. He didn't pay much attention to Talley. He had that dogged, uncomfortable feeling a man has when he knows he doesn't qualify as an expert, but feels that he's hit on something the experts have missed.

Half an hour after the evening mess--near sunset--a security officer wearing a uniform hunted up Joe at the airfield.

"Major Holt sent me over to bring you back to the Shed," he said politely.

"If you don't mind," said Joe with equal politeness, "I'll check that."

He went to the phone booth in the barracks. He got Major Holt on the wire. And Major Holt hadn't sent anybody to get him.

So Joe stayed in the telephone booth--on orders--while the Major did some fast telephoning. It was comforting to know he had a pistol in his pocket, and it was frustrating not to be allowed to try to capture the fake security officer himself. The idea of murdering Joe had not been given up, and he'd have liked to take part personally in protecting himself. But it was much more important for the fake security man to be captured than for Joe to have the satisfaction of attempting it himself.

As a matter of fact, the fake officer started his getaway the instant Joe went to check on his orders. The officer knew they'd be found faked. It had not been practical for him to shoot Joe down where he was. There were too many people around for this murderer to have a chance at a getaway.

But he didn't get away, at that. Twenty minutes later, while Joe still waited fretfully in the phone booth, the phone bell rang and Major Holt was again on the wire. And this time Joe was instructed to come back to the Shed. He had exact orders whom to come with, and they had orders which identified them to Joe.

Some eight miles from the airfield--it was just dusk--Joe came upon a wrecked car with motorcycle security guards working on it. They stopped Joe's escort. Joe's phone call had set off an alarm. A plane had spotted this car tearing away from the airfield, and motorcyclists were guided in pursuit by the plane. When it wouldn't stop--when the fake Security officer in it tried to shoot his way clear--the plane strafed him. So he was dead and his car was a wreck, and the motorcycle men were trying to get some useful information from his body and the car.

Joe went to the Major's house in the officers'-quarters area. The Major looked even more tired than before, but he nodded approvingly at Joe. Sally was there too, and she regarded Joe with a look which was a good deal warmer than her father's.

"You did very well," said the Major detachedly. "I don't have too high an opinion of the brains of anybody your age, Joe. When you are my age, you won't either. But whether you have brains or simply luck, you are turning out to be very useful."

Joe said: "I'm getting security conscious, sir. I want to stay alive."

The Major regarded him with irony.

"I was thinking of the fact that when you worked out the matter of the doctored pushpot fuel, you did not try to be a hero and prove it yourself. You referred it to me. That was the proper procedure. You could have been killed, investigating--it's clear that the saboteurs would be pleased to have a good chance to murder you--and your suspicions might never have reached me. They were correct, by the way. One storage tank underground was half-full of doctored fuel. Rather more important, another _was_ full, not yet drawn on."

The Major went on, without apparent cordiality: "It seems probable that if this particular sabotage trick had not been detected--it seems likely that on the Platform's take-off, all or most of the pushpots would have been fueled to explode at some time after the Platform was aloft, and before it could possibly get out to space."

Joe felt queer. The Major was telling him, in effect, that he might have kept the Platform from crashing on take-off. It was a good but upsetting sensation. It was still more important to Joe that the Platform get out to space than that he be credited with saving it. And it was not reassuring to hear that it might have been wrecked.

"Your reasoning," added the Major coldly, "was soundly based. It seems certain that there is not one central authority directing all the sabotage against the Platform. There are probably several sabotage organizations, all acting independently and probably hating each other, but all hating the Platform more."

Joe blinked. He hadn't thought of that. It was disheartening.

"It will really be bad," said the Major, "if they ever co-operate!"

"Yes, sir," said Joe.

"But I called you back from the airfield," the Major told him without warmth, "to say that you have done a good job. I have talked to Washington. Naturally, you deserve a reward."

"I'm doing all right, sir," said Joe awkwardly. "I want to see the Platform go up and stay up!"

The Major nodded impatiently.

"Naturally! But--ah--one of the men selected and trained for the crew of the Platform has been--ah--taken ill. In strict confidence, because of sabotage it has been determined to close in the Platform and get it aloft at the earliest possible instant, even if its interior arrangements are incomplete. So--ah--in view of your usefulness, I said to Washington that I believed the greatest reward you could be offered was--ah--to be trained as an alternate crew member, to take this man's place if he does not recover in time."

The room seemed to reel around Joe. Then he gulped and said: "Yes, sir! I mean--that's right. I mean, I'd rather have that, than all the money in the world!"

"Very well." The Major turned to leave the room. "You'll stay here, be guarded a good deal more closely than before, and take instructions. But you understand that you are still only an alternate for a crew member! The odds are definitely against your going!"

"That's--that's all right, sir," said Joe unsteadily. "That's quite all right!"

The Major went out. Joe stood still, trying to realize what all this might mean to him. Then Sally stirred.

"You might say thanks, Joe."

Her eyes were shining, but she looked proud, too.

"I put it in Dad's head that that was what you'd like better than anything else," she told him. "If I can't go up in the Platform myself--and I can't--I wanted you to. Because I knew you wanted to."

She smiled at him as he tried incoherently to talk. With a quiet maternal patience, she led him out on the porch of her father's house and sat there and listened to him. It was a long time before he realized that she was humoring him. Then he stopped short and looked at her suspiciously. He found that in his enthusiastic gesticulations he had been gesticulating with _her_ hand as well as his own.

"I guess I'm pretty crazy," he said ruefully. "Shooting off my mouth about myself up there in space.... You're pretty decent to stand me the way I am, Sally."

He paused. Then he said humbly: "I'm plain lucky. But knowing you and--having you like me reasonably much is pretty lucky too!"

She looked at him noncommittally.

He added painfully: "And not only because you spoke to your father and told him just the right thing, either. You're--sort of swell, Sally!"

She let out her breath. Then she grinned at him.

"That's the difference between us, Joe," she told him. "To me, what you just said is the most important thing anybody's said tonight."

10

The world turned over on its axis with unfailing regularity, and nights followed mornings and mornings followed nights according to well-established precedent. One man turned up in Bootstrap with radiation burns, but he had not offered himself for check over at the hospital. He was found dead in his lodging. Since nobody else appeared to have suffered any burns at all, it was assumed that he was the messenger who had brought the radioactive cobalt to Braun, who also had been doomed by possession of the deadly stuff, but who had broken the chain of fatality by not dumping it free into the air of the Shed. Under the circumstances, then, three-shift work on the Platform was resumed, and three times in each twenty-four hours fleets of busses rolled out of Bootstrap carrying men to work in the Shed, and rolled back again loaded with men who had just stopped working there.

Trucks carried materials to the Shed, and swing-up doors opened in the great dome's eastern wall, and the trucks went in and unloaded. Then the trucks went out of the same doors and trundled back for more materials. In the Shed, shining plates of metal swung aloft, and welding torches glittered in the maze of joists and upright pipes that still covered the monster shape. Each day it was a little more nearly complete. In a separate, guarded workshop by a sidewall, the Chief and Haney and Mike the midget labored mightily to accomplish the preposterous. They grew lean and red-eyed from fatigue, and short of temper and ever more fanatical--and security men moved about in seeming uselessness but never-ceasing vigilance.

There were changes, though. The assembly line of pushpots grew shorter, and the remaining monstrosities around the sidewall were plainly near to completion. There came a day, indeed, when only five ungainly objects remained on that line, and even they were completely plated in and needed only a finishing touch. It was at this time that more crates and parcels arrived from the Kenmore Precision Tool plant, and Joe dropped his schoolroomlike instruction course in space flight for work of greater immediate need. He and his allies worked twice around the clock to assemble the replaced parts with the repaired elements of the pilot gyros. They grew groggy from the desperate need both for speed and for absolute accuracy, but they put the complex device together, and adjusted it, and surveyed the result through red-rimmed eyes, and were too weary to rejoice.

Then Joe threw a switch and the reconstituted pilot gyro assembly began to hum quietly, and the humming rose to a whine, and the whine went deliberately up the scale until it ceased to be audible at all. Presently a dial announced the impossible, and they gazed at a device that seemed to be doing nothing whatever. The gyros appeared quite motionless. They spun with such incredible precision that it was not possible to detect that they moved a hairbreadth. And the whole complex device looked very simple and useless.

But the four of them gazed at it--now that it worked--with a sudden passionate satisfaction. Joe moved a control, and the axis of the device moved smoothly to a new place and stayed there. He moved the control again, and it moved to another position and stayed there. And to another and another and another.

Then the Chief took Joe's place, and under his hand the seemingly static disks--which were actually spinning at forty thousand revolutions per minute--turned obediently and without any appearance of the spectacular. Then Haney worked the controls. And Mike put the device through its paces.

Mike left the gyros spinning so that the main axis pointed at the sun, invisible beyond the Shed's roof. And then all four of them watched. It took minutes for this last small test to show its results. But visibly and inexorably the pilot gyros followed the unseen sun, and they would have resisted with a force of very many tons any attempt to move them aside by so little as one-tenth of a second of arc, which would mean something like one three-hundred-thousandth of a right angle. And these pilot gyros would control the main gyros with just this precision, and after the Platform was out in space could hold the Platform itself with the steadiness needed for astronomical observation past achievement from the surface of the Earth.

The pilot gyros, in a word, were ready for installation.

Joe and Haney and the Chief and Mike were not beautiful to look at. They were begrimed from head to toe, and their eyes were bloodshot, and they were exhausted to the point where they did not even notice any longer that they were weary. And their mental processes were not at all normal, so that they were quarrelsome and arbitrary and arrogant to the men with the flat-bed trailer who came almost reverently to move their work. They went jealously with the thing they had rebuilt, and they were rude to engineers and construction workers and supervisors, and they shouted angrily at each other as it was hoisted up a shaft that had been left in the Platform for its entrance, and they were very far from tactful as they watched with hot, anxious eyes as it was bolted into place.

It would be welded later, but first it was tried out. And it moved the main gyros! They weighed many times what the pilot gyros did, but even when they were spinning the pilot gyros stirred them. Of course the main-gyro linkage to the fabric of the Shed had to be broken for this test, or the gyros would have twisted the giant upon its support and all the scaffolding around it would have been broken and the men on it killed.

But the gyros worked! They visibly and unquestionably worked! They controlled the gigantic wheels that would steer the Platform in its take-off, and later would swing it to receive the cargo rockets coming up from Earth. The pilot instrument worked! There was no vibration. In its steering apparatus the Platform was ready for space!

Then the Chief yawned, and his eyes glazed as he stood in the huge gyro room. And Haney's knees wobbled, and he sat down and was instantly asleep. Then Joe vaguely saw somebody--it was Major Holt--holding Mike in his arms as if Mike were a baby. Mike would have resented it furiously if he had been awake. And then suddenly Joe didn't know what was going on around him, either.

There was a definite hiatus in his consciousness. He came back to awareness very slowly. He was half-awake and half-asleep for a long time. He only knew contentedly that his job was finished. Then, slowly, he realized that he was in a bunk in one of the Platform sleeping cabins, and the inflated cover that was Sally's contribution to the Platform held him very gently in place. Somehow it was infinitely soothing, and he had an extraordinary sensation of peacefulness and relaxation and fulfillment. The pilot gyros were finished and in position. His responsibility to them was ended. And he had slept the clock around three times. He'd slept for thirty-six hours. He was starving.

Sally had evidently constituted herself a watch over Joe as he slept, because she faced him immediately when he went groggily out of the cabin to look for a place to wash. He was still covered with the grime of past labor, and he had been allowed to sleep with only his shoes removed. He was not an attractive sight. But Sally regarded him with an approval that her tone belied.

"You can get a shower," she told him firmly, "and then I'll have some breakfast for you. Fresh clothes are waiting, too."

Joe said peacefully: "The gyros are finished and they work!"

"Don't I know?" demanded Sally. "Go get washed and come back for breakfast. The Chief and Haney and Mike are already awake. And because of the four of you, they've been able to advance the Platform's take-off time--to just two days off! It leaked out, and now it's official. And you made it possible!"