Time passed. Hours, then days. Things began to happen. Trucks appeared, loaded down with sacks of white powder. The powder was very messily mixed with water and smeared lavishly over the now waterproofed wooden mockup of a space ship. It came off again in sections of white plaster, which were numbered and set to dry in warm chambers that were constructed with almost magical speed. More trucks arrived, bearing such diverse objects as loads of steel turnings, a regenerative helium-cooling plant from a gaswell—it could cool metal down to the point where it crumbled to impalpable powder at a blow—and assorted fuel tanks, dynamos, and electronic machinery.

Ten days after Mike's first proposal of concreted steel as a material for space ship construction, the parts of the first casting of the mockup were assembled. They were a mold for the hull of a space ship. There were more plaster sections for a second mold ready to be dried out now, but meanwhile vehicles like concrete mixers mixed turnings and filings and powder in vast quantities and poured the dry mass here and there in the first completed mold. Then men began to wrap the gigantic object with iron wire. Presently that iron wire glowed slightly, and the whole huge mold grew hotter and hotter and hotter. And after a time it was allowed to cool.

But that did not mean a ceasing of activity. The plaster casts had been made while the concreting process was worked out. The concreting process—including the heating—was in action while fittings were being flown to the Shed. But other hulls were being formed by metal-concrete formation even before the first mold was taken down.

When the plaster sections came off, there was a long, gleaming, frosty-sheened metal hull waiting for the fittings. It was a replacement of one of the two shot-down space craft, ready for fitting out some six weeks ahead of schedule. Next day there was a second metal hull, still too hot to touch. The day after that there was another.

Then they began to be turned out at the rate of two a day, and all the vast expanse of the Shed resounded with the work on them. Drills drilled and torches burned and hammers hammered. Small diesels rumbled. Disk saws cut metal like butter by the seemingly impractical method of spinning at 20,000 revolutions per minute. Convoys of motor busses rolled out from Bootstrap at change-shift time, and there were again Security men at every doorway, moving continually about.

But it still didn't look too good. There is apparently no way to beat arithmetic, and a definitely grim problem still remained. Ten days after the beginning of the new construction program, Joe and Sally looked down from a gallery high up in the outward-curving wall of the Shed. Acres of dark flooring lay beneath them. There was a spiral ramp that wound round and round between the twin skins of the fifty-story-high dome. It led finally to the Communications Room at the very top of the Shed itself.

Where Joe and Sally looked down, the floor was 300 feet below. Welding arcs glittered. Rivet guns chattered. Trucks came in the doorways with materials, and there was already a gleaming row of eighty-foot hulls. There were eleven of them already uncovered, and small trucks ran up to their sides to feed the fitting-out crews such items as air tanks and gyro assemblies and steering rocket piping and motors, and short wave communicators and control boards. Exit doors were being fitted. The last two hulls to be uncovered were being inspected with portable x-ray outfits, in search of flaws. And there were still other ungainly white molds, which were other hulls in process of formation—the metal still pouring into the molds in powder form, or being tamped down, or being sintered to solidity.

Joe leaned on the gallery-railing and said unhappily, "I can't help worrying, even though the Platform hasn't been shot at since we landed."

That wasn't an expression of what he was thinking. He was thinking about matters the enemies of the Platform would have liked to know about. Sally knew these matters too. But top secret information isn't talked about by the people who know it, unless they are actively at work on it. At all other times one pretends even to himself that he doesn't know it. That is the only possible way to avoid leaks.

The top secret information was simply that it was still impossible to supply the Platform. Ships could be made faster than had ever been dreamed of before, but so long as any ship that went up could be destroyed on the way down, the supply of the Platform was impractical. But the ships were being built regardless, against the time when a way to get them down again was thought of. As of the moment it hadn't been thought of yet.

But building the ships anyhow was unconscious genius, because nobody but Americans could imagine anything so foolish. The enemies of the Platform and of the United States knew that full-scale production of ships by some fantastic new method was in progress. The fact couldn't be hidden. But nobody in a country where material shortages were chronic could imagine building ships before a way to use them was known. So the Platform's enemies were convinced that the United States had something wholly new and very remarkable, and threatened their spies with unspeakable fates if they didn't find out what it was.

They didn't find out. The rulers of the enemy nations knew, of course, that if a new—say—space-drive had been invented, they would very soon have to change their tune. So there were no more attacks on the Platform. It floated serenely overhead, sending down astronomical observations and solar-constant measurements and weather maps, while about it floated a screen of garbage and discarded tin cans.

But Joe and Sally looked down where the ships were being built while the problem of how to use them was debated.

"It's a tough nut to crack," said Joe dourly.

It haunted him. Ships going up had to have crews. Crews had to come down again because they had to leave supplies at the Platform, not consume them there. Getting a ship up to orbit was easier than getting it down again.

"The Navy's been working on light guided missiles," said Sally.

"No good," snapped Joe.

It wasn't. He'd been asked for advice. Could a space ship crew control guided missiles and fight its way back to ground with them? The answer was that it could. But guided missiles used to fight one's way down would have to be carried up first. And they would weigh as much as all the cargo a ship could carry. A ship that carried fighting rockets couldn't carry cargo. Cargo at the Platform was the thing desired.

"All that's needed," said Sally, watching Joe's face, "is a slight touch of genius. There's been genius before now. Burning your cabin free with landing-rocket flames——"

"Haney's idea," growled Joe dispiritedly.

"And making more ships in a hurry with metal-concrete——"

"Mike did that," said Joe ruefully.

"But you made the garbage-screen for the Platform," insisted Sally.

"Sanford had made a wisecrack," said Joe. "And it just happened that it made sense that he hadn't noticed." He grimaced. "You say something like that, now...."

Sally looked at him with soft eyes. It wasn't really his job, this worrying. The top-level brains of the armed forces were struggling with it. They were trying everything from redesigned rocket motors to really radical notions. But there wasn't anything promising yet.

"What's really needed," said Sally regretfully, "is a way for ships to go up to the Platform and not have to come back."

"Sure!" said Joe ironically. Then he said, "Let's go down!"

They started down the long, winding ramp which led between the two skins of the Shed's wall. It was quite empty, this long, curving, descending corridor. It was remarkably private. In a place like the Shed, with frantic activity going on all around, and even at Major Holt's quarters where Sally lived and Joe was a guest, there wasn't often a chance for them to talk in any sort of actual privacy.

But Joe went on, scowling. Sally went with him. If she seemed to hang back a little at first, he didn't notice. Presently she shrugged her shoulders and ceased to try to make him notice that nobody else happened to be around. They made a complete circuit of the Shed within its wall, Joe staring ahead without words.

Then he stopped abruptly. His expression was unbelieving. Sally almost bumped into him.

"What's the matter?"

"You had it, Sally!" he said amazedly. "You did it! You said it!"

"What?"

"The touch of genius!" He almost babbled. "Ships that can go up to the Platform and not have to come back! Sally, you did it! You did it!"

She regarded him helplessly. He took her by the shoulders as if to shake her into comprehension. But he kissed her exuberantly instead.

"Come on!" he said urgently. "I've got to tell the gang!"

He grabbed her hand and set off at a run for the bottom of the ramp. And Sally, with remarkably mingled emotions showing on her face, was dragged in his wake.

He was still pulling her after him when he found the Chief and Haney and Mike in the room at Security where they were practically self-confined, lest their return to Earth become too publicly known. Mike was stalking up and down with his hands clasped behind his back, glum as a miniature Napoleon and talking bitterly. The Chief was sprawled in a chair. Haney sat upright regarding his knuckles with a thoughtful air.

Joe stepped inside the door. Mike continued without a pause: "I tell you, if they'll only use little guys like me, the cabin and supplies and crew can be cut down by tons! Even the instruments can be smaller and weigh less! Four of us in a smaller cabin, less grub and air and water—we'll save tons in cabin-weight alone! Why can't you big lummoxes see it?"

"We see it, Mike," Haney said mildly. "You're right. But people won't do it. It's not fair, but they won't."

Joe said, beaming, "Besides, Mike, it'd bust up our gang! And Sally's just gotten the real answer! The answer is for ships to go up to the Platform and not come back!"

He grinned at them. The Chief raised his eyebrows. Haney turned his head to stare. Joe said exuberantly: "They've been talking about arming ships with guided missiles to fight with. Too heavy, of course. But—if we could handle guided missiles, why couldn't we handle drones?"

The three of them gaped at him. Sally said, startled, "But—but, Joe, I didn't——"

"We've got plenty of hulls!" said Joe. Somehow he still looked astonished at what he'd made of Sally's perfectly obvious comment. "Mike's arranged for that! Make—say—six of 'em into drones—space barges. Remote-controlled ships. Control them from one manned ship—the tug! We'll ride that! Take 'em up to the Platform exactly like a tug tows barges. The tow-line will be radio beams. We'll have a space-tow up, and not bother to bring the barges back! There won't be any landing rockets! They'll carry double cargo! That's the answer! A space tug hauling a tow to the Platform!"

"But, Joe," insisted Sally, "I didn't think of——"

The Chief heaved himself up. Haney's voice cut through what the Chief was about to say. Haney said drily: "Sally, if Joe hadn't kissed you for thinking that up, I would. Makes me feel mighty dumb."

Mike swallowed. Then he said loyally, "Yeah. Me too. I'd've made a two-ton cargo possible—maybe. But this adds up. What does the major say?"

"I—haven't talked to him. I'd better, right away." Joe grinned. "I wanted to tell you first."

The Chief grunted. "Good idea. But hold everything!" He fumbled in his pocket. "The arithmetic is easy enough, Joe. Cut out the crew and air and you save something." He felt in another pocket. "Leave off the landing rockets, and you save plenty more. Count in the cargo you could take anyhow"—— he searched another pocket still——"and you get forty-two tons of cargo per space barge, delivered at the Platform. Six drones—that's 252 tons in one tow! Here!" He'd found what he wanted. It was a handkerchief. He thrust it upon Joe. "Wipe that lipstick off, Joe, before you go talk to the major. He's Sally's father and he might not like it."

Joe wiped at his face. Sally, her eyes shining, took the handkerchief from him and finished the job. She displayed that remarkable insensitivity of females in situations productive of both pride and embarrassment. When a girl or a woman is proud, she is never embarrassed.

She and Joe went away, and Sally rushed right into her father's office. In fifteen minutes technical men began to arrive for conferences, summoned by telephone. Within forty-five minutes, messengers carried orders out to the Shed floor and stopped the installation of certain types of fittings in all but one of the hulls. In an hour and a half, top technical designers were doing the work of foremen and getting things done without benefit of blueprints. The proposal was beautifully simple to put into practice. Guided-missile control systems were already in mass production. They could simply be adjusted to take care of drones.

Within twelve hours there were truck-loads of new sorts of supplies arriving at the Shed. Some were Air Force supplies and some were Ordnance, and some were strictly Quartermaster. These were not component parts of space ships. They were freight for the Platform.

And, just forty-eight hours after Joe and Sally looked dispiritedly down upon the floor of the Shed, there were seven gleaming hulls in launching cages and the unholy din of landing pushpots outside the Shed. They came with hysterical cries from their airfield to the south, and they flopped flat with extravagant crashings on the desert outside the eastern door.

By the time the pushpots had been hauled in, one by one, and had attached themselves to the launching cages, Joe and Haney and the Chief and Mike had climbed into the cabin of the one ship which was not a drone. There were now seven cages in all to be hoisted toward the sky. A great double triangular gore had been jacked out and rolled aside to make an exit in the side of the Shed. Nearly as many pushpots, it seemed, were involved in this launching as in the take-off of the Platform itself.

The routine test before take-off set the pushpot motors to roaring inside the Shed. The noise was the most sustained and ghastly tumult that had been heard on Earth since the departure of the Platform.

But this launching was not so impressive. It was definitely untidy, imprecise, and unmilitary. There were seven eighty-foot hulls in cages surrounded by clustering, bellowing, preposterous groups of howling objects that looked like over-sized black beetles. One of the seven hulls had eyes. The others were blind—but they were equipped with radio antennae. The ship with eyes had several small basket-type radar bowls projecting from its cabin plating.

The seven objects rose one by one and went bellowing and blundering out to the open air. At 40 and 50 feet above the ground, they jockeyed into some sort of formation, with much wallowing and pitching and clumsy maneuvering.

Then, without preliminary, they started up. They rose swiftly. The noise of their going diminished from a bellow to a howl, and from a howl to a moaning noise, and then to a faint, faint, ever-dwindling hum.

Presently that faded out, too.

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