Isaac Asimov - Robot Dreams

Rioz was swearing fluently and nearly continuously. He continued to have the impulse to drag the back of his hand across his forehead in order to wipe away the accumulating sweat. The few times that he had succumbed to the impulse, metal had met silicone with a clash that rang loudly inside his suit, but served no useful purpose. The desiccators within the suit were sucking at maximum and, of course, recovering the water and restoring ion-exchanged liquid, containing a careful proportion of salt, into the appropriate receptacle.

Rioz yelled, "Damn it, Dick, wait till I give the word, will you?"

And Swenson’s voice rang in his ears, "Well, how long am I supposed to sit here?"

"Till I say," replied Rioz.

He strengthened pseudo-grav and lifted the projector a bit. He released pseudo-grav, insuring that the projector would stay in place for minutes even if he withdrew support altogether. He kicked the cable out of the way (it stretched beyond the close "horizon" to a power source that was out of sight) and touched the release.

The material of which the fragment was composed bubbled and vanished under its touch. A section of the lip of the tremendous cavity he had already carved into its substance melted away and a roughness in its contour had disappeared.

"Try it now," called Rioz.

Swenson was in the ship that was hovering nearly over Rioz’s head.

Swenson called, " All clear?"

"I told you to go ahead."

It was a feeble flicker of steam that issued from one of the ship’s forward vents. The ship drifted down toward the ring fragment. Another flicker adjusted a tendency to drift sidewise. It came down straight.

A third flicker to the rear slowed it to a feather rate.

Rioz watched tensely. "Keep "her coming. You’ll make it. You’ll make it."

The rear of the ship entered the hole, nearly filling it. The bellying walls came closer and closer to its rim. There was a grinding vibration as the ship’s motion halted.

It was Swenson’s turn to curse. "It doesn’t fit," he said.

Rioz threw the projector groundward in a passion and went flailing up into space. The projector kicked up a white crystalline dust all about it, and when Rioz came down under pseudo-grav, he did the same.

He said, "You went in on the bias, you dumb Grounder."

"I hit it level, you dirt-eating farmer."

Backward-pointing side jets of the ship were blasting more strongly than before, and Rioz hopped to get out of the way.

The ship scraped up from the pit, then shot into space half a mile before forward jets could bring it to a halt.

Swenson said tensely, "We’ll spring half a dozen plates if we do this once again. Get it right, will you?"

"I’ll get it right. Don’t worry about it. Just you come in right."

Rioz jumped upward and allowed himself to climb three hundred yards to get an overall look at the cavity. The gouge marks of the ship were plain enough. They were concentrated at one point halfway down the pit. He would get that.

It began to melt outward under the blaze of the projector.

Half an hour later the ship snuggled neatly into its cavity, and Swenson, wearing his space suit, emerged to join Rioz. Swenson said, "If you want to step in and climb out of the suit, I’ll take care of the icing."

"It’s all right," said Rioz. "I’d just as soon sit here and watch Saturn."

He sat down at the lip of the pit. There was a six-foot gap between it and the ship. In some places about the circle, it was two feet; in a few places, even merely a matter of inches. You couldn’t expect a better fit out of handwork. The final adjustment would be made by steaming ice gently and letting it freeze into the cavity between the lip and the ship.

Saturn moved visibly across the sky, its vast bulk inching below the horizon."

Rioz said, "How many ships are left to put in place?"

Swenson said, "Last I heard, it was eleven. We’re in now, so that means only ten. Seven of the ones that are placed are iced in. Two or three are dismantled."

"We’re coming along fine."

"There’s plenty to do yet. Don’t forget the main jets at the other end. And the cables and the power lines. Sometimes I wonder if we’ll make it. On the way out, it didn’t bother me so much, but just now I was sitting at the controls and I was saying, ‘We won’t make it. We’ll sit out here and starve and die with nothing but Saturn over us.’ It makes me feel – "

He didn’t explain how it made him feel. He just sat there. Rioz said, "You think too damn much."

"It’s different with you," said Swenson. "I keep thinking of Pete – and Dora."

"What for? She said you could go, didn’t she? The Commissioner gave her that talk on patriotism and how you’d be a hero and set for life once you got back, and she said you could go. You didn’t sneak out the way Adams did."

"Adams is different. That wife of his should have been shot when she was born. Some women can make hell for a guy, can’t they? She didn’t want him to go – but she’d probably rather he didn’t come back if she can get his settlement pay."

"What’s your kick, then? Dora wants you back, doesn’t she?"

Swenson sighed. "I never treated her right."

"You turned over your pay, it seems to me. I wouldn’t do that for any woman. Money for value received, not a cent more."

"Money isn’t it. I get to thinking out here. A woman likes company. A kid needs his father. What am I doing way out here?"

"Getting set to go home."

"Ah-h, you don’t understand."

Ted Long wandered over the ridged surface of the ring fragment with his spirits as icy as the ground he walked on. It had all seemed perfectly logical back on Mars, but that was Mars. He had worked it out carefully in his mind in perfectly reasonable steps. He could still remember exactly how it went..

It didn’t take a ton of water to move a ton of ship. It was not mass equals mass, but mass time!! velocity equals mass times velocity. It didn’t matter, in other words, whether you shot out a ton of water at a mile a second or a hundred pounds of water. at twenty miles a second. You got the same final velocity out of the ship.

That meant the jet nozzles had to be made narrower and the steam hotter. But then drawbacks appeared. The narrower the nozzle, the more energy was lost in friction and turbulence. The hotter the steam, the more refractory the nozzle had to be and the shorter its life. The limit in that direction was quickly reached.

Then, since a given weight of water could move considerably more than its own weight under the narrow-nozzle conditions, it paid to be big. The bigger the water – storage space, the larger the size of the actual travel-head, even in proportion. So they started to make liners heavier and bigger. But then the larger the shell, the heavier the bracings, the more difficult the weldings, the more exacting the engineering requirements. At the moment, the limit in that direction had been reached also.

And then he had put his finger on what had seemed to him to be the basic flaw – the original unswervable conception that the fuel had to be placed inside the ship; the metal had to be built to encircle a million tons of water.

Why? Water did not have to be water. It could be ice, and ice could be shaped. Holes could be melted into it. Travelheads and jets could be fitted into it. Cables could hold travelheads and jets stiffly together under the influence of magnetic field-force grips.

Long felt the trembling of the ground he walked on. He was at the head of the fragment. A dozen ships were blasting in and out of sheaths carved in its substance, and the fragment shuddered under the continuing impact.

The ice didn’t have to be quarried. It existed in proper chunks in the rings of Saturn. That’s all the rings were – pieces of nearly pure ice, circling Saturn. So spectroscopy stated and so it had turned out to be. He was standing on one such piece now, over two miles long, nearly one mile thick. It was almost half a billion tons of water, all in one piece, and he was standing on it.