Lucky Starr And The Rings Of Saturn ls-6

by Isaac Asimov

  Lucky said, "That's gravel, Bigman. The Cassini division is clear of it, compared with the rings them selves, but they're not a hundred per cent clear. If we hit one of those bits on the way through… "

  "One chance in a thousand," broke in Wess, shrugging it off.

  "One chance in a million," said Lucky coolly, "but it was that one chance in a million that got Agent X in The Net of Space… We're about at the boundary of the division proper." His hand held firmly at the controls.

  Bigman drew a deep breath, tensing for the possible puncture that would rip the hull and perhaps short the proton micro-pile into a spreading blaze of red energy. At least it would be over before…

  Lucky said, "Made it."

  Wess let out his breath noisily.

  Bigman said, "Are we through?"

  "Of course we're through, you dumb Martian," said Wess. "The rings are only ten miles thick, and how many seconds do you think it takes us to make ten miles?"

  "And we're on the other side?"

  "You bet. Try to find the rings on the visiplate."

  Bigman veered the view one way, then back hi the other direction, then over and over again in continuously longer sweeps. "Sands of Mars, there's a kind of shadowy outline there."

  "And that's all you'll see, little pal. You're on the shadow side of the rings now. The Sun's lighting up the other side, and the light doesn't seep through ten miles of thick gravel. Say, Bigman, what do they teach for astronomy in the Martian schools, anyway-Twinkle, twinkle, little star'?"

  Bigman's lower lip thrust out slowly. "You know, lardhead, I'd like to have you one season on the Martian farms. I'd render some of the fat off you and get down to what meat you have, about ten pounds of it-and all of it in your big feet."

  Lucky said, ''I'd appreciate it, Wess, if you and Bigman would put a bookmark in that argument you're having and save it for later. Would you check on the mass detector, please?"

  "Sure thing, Lucky. Hey, it's way off kilter. How sharply are you changing course?"

  "As sharply as the ship will take. We're staying under the rings all the distance we can."

  Wess nodded. "Okay, Lucky. That knocks out their mass detection."

  Bigman grinned. It worked out perfectly. No mass detector could spot The Shooting Starr because of the interference of the mass of Saturn's rings, and even visual detection was unlikely through the rings.

  Lucky's long legs stretched out, and the muscles of his back moved smoothly as he stretched and flexed some of the tension out of his arms and shoulders.

  "I doubt," said Lucky, "that any of the Sirian ships will have the nerve to follow us through the gap. They don't have Agrav."

  "Okay," said Bigman, "so far, so good. But where do we go now? Will anyone tell me?"

  "No secret," said Lucky. "We're heading for Mimas. We hug the rings till we're as close to Mimas as we can get, then make the dash across the intervening space. Mimas is only thirty thousand miles outside the rings."

  "Mimas? That's one of the moons of Saturn, right?"

  "Right," said Wess, breaking in. "The nearest one to the planet."

  Their course had flattened out now, and The Shooting Starr was still moving around Saturn, but west to east now, in a plane parallel with the rings.

  Wess sat down on the blanket, legs crossed under him like a tailor, and said, "Would you like to learn a little more astronomy? If you can find a little room in that walnut you have in your hollow skull, I can tell you why there's a division in the rings."

  Curiosity and scorn battled in the small Martian. He said, "Let's see you make up something fast, you ignorant cobber. Go ahead, I call your bluff."

  "No bluff," said Wess haughtily. "Listen and learn. The inner parts of the two rings rotate about Saturn in five hours. The outermost parts make the rotation in fifteen hours. Right where Cassini's division is, the ring material, if there were any there, would go around at an intermediate rate, twelve hours per circuit."

  "So what?"

  "So the satellite Mimas, the one we're heading for, travels around Saturn in twenty-four hours."

  "Again, so what?"

  "All the particles in the ring are pulled this way and that by the satellites as they and the satellites move about Saturn. Mimas does most of the pulling because it is the closest. Mostly the pulls are in one direction now and in another direction an hour from now, so that they cancel out. If there were gravel in Cassini's division, however, every second time it completed its rotation it would find Mimas in the same spot in the sky, pulling in the same old direction. Some of the gravel is constantly pulled ahead, so that it spirals outward into the outer ring; and some of it is pulled back, so that it spirals inward into the inner ring. They don't stay where they are; a section of the ring empties of particles and bingo-you have Cassini's division and two rings."

  "Is that so?" said Bigman weakly (he felt reasonably certain Wess was giving him the correct story). "Then how come there is some gravel in the division? Why isn't it all moved out by now?"

  "Because," said Wess with a lofty air of superiority, "some is always being pushed in or pulled in by random gravitational effects of the satellites, but none of it ever stays long… And I hope you're taking notes on all this, Bigman, because I may ask questions on this later."

  "Go fry your skull in a mesonic blast," muttered Bigman.

  Wess returned to his mass detectors again, smiling. He fiddled with them a moment, then with no trace of the preceding banter left on his leathery face, he bent down closely.

  "Lucky!"

  "Yes, Wess?"

  "The rings aren't masking us."

  "What?"

  "Well, look for yourself. The Sirians are getting closer. The rings aren't bothering them at all."

  Lucky said thoughtfully, "Why, how can that be?"

  "It can't be blind luck that's converging eight ships on our orbit. We've made a right-angle bend and they've adjusted their orbits to suit. They must be detecting us."

  Lucky stroked his chin with his knuckles. "If they're doing it, then, Great Galaxy, they're doing it. There's no use in reasoning out the fact that they can't do it. It might mean that they have something we don't have."

  "No one ever said the Sirians were dummies," said Wess.

  "No, but sometimes there's a tendency among us to act as though they were; as though all scientific advance comes out of the minds of the Council of Science and that unless the Sirians steal our secrets they have nothing. And sometimes I fall into that particular trap too… Well, here we go."

  "Where do we go?" demanded Bigman sharply.

  "I told you already, Bigman," said Lucky. "Mimas."

  "But they're after us."

  "I know. Which just means we've got to get there faster than ever… Wess, can they cut us off before we get to Mimas?"

  Wess worked quickly. "Not unless they can accelerate at least three times faster than we can, Lucky."

  "All right. Giving the Sirians all the credit in the world, I can't believe they can have that much more power than the Shooter. So we'll make it."

  Bigman said, "But, Lucky, you're crazy. Let's fight or get out of the Saturnian system altogether. We can't land on Mimas."

  Lucky said, "Sorry, Bigman, we have no choice. We've got to land on Mimas."

  "But they've got us spotted. They'll just follow us down to Mimas and we'll have to fight then, so why not fight now while we can maneuver with our Agrav and they can't?"

  "They might not bother to follow us down to Mimas."

  "Why shouldn't they?"

  "Well, Bigman, did we bother to go into the rings and pull out what was left of The Net of Space?"

  "But that ship blew up."

  "Exactly."

  There was silence in the control room. The Shooting Starr streaked through space, curving slowly away from Saturn, then more quickly, slipping out from under the outermost ring and into open space. Ahead of it now lay Mimas, a glittering world seen in tiny crescent. It was only 320 miles in
diameter.

  Still far away were the converging ships of the Sirian fleet.

  Mimas grew in size, and finally The Shooting Starr's forward thrust burst into action and the ship began a deceleration.

  But to Bigman it seemed incredible that the space-wise Lucky could have so miscalculated. He said tightly, "Too late, Lucky. We'll never slow up enough for a landing. We'll have to go into a spiral orbit until we lose enough velocity."

  "No time for spiraling Mimas, Bigman. We're heading straight in."

  "Sands of Mars, we can't! Not at this speed!"

  "That's what I hope the Sirians will decide."

  "But, Lucky, they'd be right."

  Wess put in slowly, "Hate to say it, Lucky, but I agree with Bigman."

  "No time to argue or explain," said Lucky. He bent over the controls.

  Mimas expanded crazily in the visiplate. Bigman licked his lips. "Lucky, if you think it's better going out this way than letting the Sirians get us, okay. I can go along. But, Lucky, if we're going to go, can't we go out fighting? Can't we maybe get one of the cobbers first?"

  Lucky shook his head and said nothing. His arms were moving quickly now, so that Bigman could not make out exactly what he was doing. Deceleration was still proceeding too slowly.

  For a moment Wess extended his hands as though to remove Lucky forcibly from the controls, but Bigman placed his hand quickly on the other's wrist. Bigman might be convinced they were going to their death, but his stubborn faith in Lucky somehow remained.

  They were slowing, slowing, slowing, in what would have been body-crushing deceleration in any ship other than The Shooting Starr, but with Mimas filling the visiplate now and hurtling at them, the slowing was not enough.

  Flashing down at deadly speed, The Shooting Starr struck the surface of Mimas.

  7. On Mimas

  And yet didn't.

  Instead, there was a keening hiss that was familiar to Bigman. It was that of a ship striking atmosphere.

  Atmosphere?

  But that was impossible. No world the size of Mimas could possibly have an atmosphere. He looked at Wess, who was suddenly sitting back on the blanket, looking worn and pale but somehow satisfied.

  Bigman strode up to Lucky, "Lucky… "

  "Not now, Bigman."

  And suddenly Bigman recognized what it was that Lucky was doing at the controls. He was manipulating the fusion beam. Bigman ran back to the visiplate and focused it dead ahead.

  There was no doubt of it, now that he finally grasped the idea. The fusion beam was the most magnificent "heat ray" ever invented. It was designed mainly as a weapon at close range, but surely no one had ever used one as Lucky was using it now.

  The jet of deuterium, snaking out forward of the ship, was pinched in by a powerful magnetic field and, at a point miles ahead, was heated to nuclear ignition by a surge of power from the micro-piles. Maintained for any length of time, the power surge necessary would have bankrupted the ship; but a fraction of a millionth of a second sufficed. After that the deuterium fusion reaction was self-sustaining and the incredible fusion flame that resulted burned in a heat of three hundred million degrees.

  That spot of heat ignited before the surface of Mimas was touched and bored into the body of the satellite as though it were not there, puncturing a tunnel into its vitals. Into that tunnel whizzed The Shooting Starr. The vaporized substance of Mimas was the, atmosphere that surrounded them, helping to decelerate them, but bringing the temperature of the ship's outer skin to dangerous redness.

  Lucky watched the skin-temperature dial and said, "Wess, put more punch in the vaporization coils."

  "It will take all the water we have," Wess said.

  "Let it. We need no water of our own on this world."

  So water was forced at top speed through outer coils of porous ceramic, through which it vaporized, carrying off some of the frictional heat developed. But the water flashed away as fast as it could be pumped into the coils. The skin temperature still rose.

  But more slowly now. Ship's deceleration had progressed, and Lucky cut the force of the deuterium jet and adjusted the magnetic field. The spot of fusing deuterium grew smaller and smaller still. The whistle of atmosphere descended in pitch.

  Finally the jet blanked out completely and the ship drifted forward into solid wall, melting a path inward a way by virtue of its own heat and finally coming to a jolting halt.

  Lucky sat back at last "Gentlemen," he said, "I'm sorry I couldn't take time to explain, but it was a last-minute decision and the control board took all my energies. Anyway, welcome to the interior of Mimas."

  Bigman pumped a deep breath into his lungs and said, "I never thought you could use a fusion jet to melt a way into a world ahead of a speeding ship."

  "You couldn't ordinarily, Bigman," said Lucky. "It just so happens that Mimas is a special case. And so is Enceladus, the next satellite out."

  "How come?"

  "They're just snowballs. Astronomers have known that since even before space travel. Their density is less than water and they reflect about eighty per cent of the light that hits them, so it's quite obvious they could only be snow, plus some frozen ammonia, and not too tightly packed at that."

  "Sure," said Wess, chiming in. "The rings are ice and these first two satellites are just collections of ice that were too far out to make up part of the rings. That's why Mimas melted so easily."

  Lucky said, "But we've got a good deal of work to do. Let's start."

  They were in a natural cavern formed by the heat of the fusion jet and closed in on all sides. The tunnel they had formed as they entered had closed as they passed, the steam condensing and freezing. The mass detector yielded figures that indicated them to be about one hundred miles below the surface of the satellite. The mass of ice above them, even under Mimas's feeble gravity, was slowly contracting the cavern.

  Slowly The Shooting Starr burrowed outward once more, like a hot wire poking into butter, and when they had reached a point within five miles of the surface, they stopped and set up an oxygen bubble.

  As a power supply was laid in along with algae tanks and a food supply, Wess shrugged resignedly and said, "Well, this is going to be home for me for a while; let's make it comfortable."

  Bigman had just awakened from his sleeping period. He screwed his face into a look of bitter condemnation.

  Wess said, "What's the matter, Bigman? All weepy because you're going to miss me?"

  Bigman snarled and said, "I'll manage. In two, three years I'll make it a point to whizz by Mimas and drop you a letter." Then he burst out, "Listen, I heard you talking while you thought I was safely asleep. What's the matter? Council secrets?"

  Lucky shook his head uneasily. "All in good time, Bigman."

  Later, when Lucky was alone with Bigman in the ship, the Councilman said, "Actually, Bigman, there's no reason you can't stay behind with Wess."

  Bigman said grumpily, "Oh, sure. Two hours cooped up with him and I'd just chop him into cubes and put him on ice for his relatives." Then he said, "Are you serious, Lucky?"

  "Rather serious. What's coming may be more dangerous for you than for me."

  "So? What do I care about that?"

  "If you stay with Wess then, whatever happens to me, you'll be picked up within two months."

  Bigman backed away. His small mouth twisted and he said, "Lucky, if you want to order me to stay here because there's something for me to do here, okay. I'll do it, and when it's done I'll join you. But if you just want me to stay here to be safe while you go off into danger, we're finished. I'll have nothing more to do with you; and without me, you overgrown cobber, you won't be able to do a thing, you know you won't." The Martian's eyes blinked rapidly.

  Lucky said, "But, Bigman… "

  "All right, I'll be in danger. Do you want me to sign a paper saying it's my own responsibility and not yours? All right, I will. Does that satisfy you, Councilman?"

  Lucky seized Bigman's hair affectionately an
d tugged his head back and forth. "Great Galaxy, trying to do you a favor is like shoveling water."

  Wess came into the ship and said, "The still is all set up and working."

  Water from the ice substance of Mimas itself poured into The Shooting Starr's reservoirs, filling them and replacing the water lost in cooling the ship's skin during the boring into Mimas. Some of the separated ammonia was carefully neutralized and stored in a skin compartment where it would be available to the algae tanks as nitrogenous fertilizer.

  And then the bubble was done and the three of them looked about at the neatly curving ice and at the almost comfortable quarters held within.

  "Okay, Wess," Lucky said at last, shaking hands firmly. "You're all set, I think."

  "As far as I can tell, Lucky, I am."

  "You'll be taken off within two months, no matter what. You'll be taken off much sooner if things break right."

  "You're assigning me this job," said Wess coolly, "and it will be done. You concentrate on yours and, by the way, take care of Bigman. Don't let him fall out of his bunk and hurt himself."

  Bigman shouted, "Don't think I don't follow all this big-shot mystery talk. You two have a deal on and you're not telling me… "

  "Into the ship, Bigman," said Lucky, picking the Martian up bodily and moving him forward, while Bigman squirmed and tried to call out an answer.

  "Sands of Mars, Lucky," he said, once they were aboard. "Look what you did. It's bad enough you're keeping your darned Council secrets, but you also let the cobber have the last word."

  "He's got the hard job, Bigman. He's got to stay put while we go out and stir up trouble, so let him have the satisfaction of the last word."

  They nudged out of Mimas at a spot from which neither Sun nor Saturn was visible. The dark sky held no object larger than Titan, low on one horizon and only a quarter of the apparent diameter of Earth's Moon.

  Its globe was half lit by the Sun, and Bigman looked somberly at its image in the visiplate. He had not regained his ebullience. He said, "And that's where the Sirians are, I suppose."

  "I think so."

  "And where do we go? Back to the rings?"