That was the most significant single action, in view of its ultimate meaning, that had been performed in the First Galaxy in ten thousand years. And yet, in a sense, it was purely a matter of form. It was not necessary for Kim to do it. He had arranged for the same effect to be produced, in time yet to come, upon every one of the three hundred million inhabited planets of the First Galaxy. The thing was automatic; implicit in the very nature of the tyrannical governments sustained by the disciplinary circuit.
Kim had simply dropped a small metal case to the surface of Donet Three. It was very strong—practically unbreakable. It contained an extremely simple electronic circuit. It fell through the frigid air of the flattened pole of Donet Three, and it struck the side of a sloping ice-mountain, and bounced and slid down to a valley and buried itself in snow, and only instants later, the small hole left by its fall was filled in and covered up completely by snow riding on a hundred-mile gale. It was undiscoverable. It was irretrievable. No device of man could detect or recover it. Kim himself could not have told where it fell.
Kim then sighted the Starshine on another distant target, and found the planet Arth, and dropped a small metal object into the depths of the humid and festering jungles along its equator. Human beings could live only in the polar regions of Arth. Then he visited a certain planet in the solar system of Tabor and a small metal case went twisting through deep water down to the seabed of its greatest ocean.
He dropped another on the shifting desert sands which cover one-third of Sind where an Emperor and Council rule in the name of a' non-existent republic, and yet another on a planet of Megar, where an otherwise unidentified Queen Amritha held imperial power, and others. . . .
He dropped one small metal case, secured from a merchant-prince on Spicus Five, on each of the planets whose troops had moved into the planets left defenseless by the vanishment of Ades.
"I wanted to do that myself, because what we've got to do next is dangerous and we may get killed," he told Dona drily. "But now we're sure that men won't stay slaves forever and now we can try to do something about Ades. I'm afraid our chances are pretty slim."
CHAPTER VII
One Chance in a Million
IN SPITE of his pessimism, Kim settled I down to the -fine calculations required for a voyage to a blue-white dwarf star not readily distinguished from others. Most inhabited planets, of course, circled sol-type suns. Light much different from that in which the race had developed was apt to have produced vegetation inimical to humanity, and useful vegetation did not thrive. And of course sol-type stars are most readily spotted by space navigators. As he checked his course with star-charts, Dona spoke softly.
"Thanks, Kim."
"For what?"
"For not wanting to put me in safety when you're going to do something dangerous. I wouldn't let you, but thanks for not trying."
"Mmmmh!" said Kim. "You're too useful."
He lined up his course and pressed the transmitter-drive stud on the control-panel. Space danced a momentary saraband,—and there was a blue-white dwarf two hundred million miles away, showing barely a planet-sized disk, but pouring out a pitiless white glare that hurt the eyes.
"That's it," said Kim. "That's the sun Alis. There should be four planets, but we're looking for Number One. It goes out beyond Two at aphelion, so we have to check the orbit—if we can find it—before we can be sure. No—we should be able to tell by the rotation. Very slow."
"And what are you going to do with it?" demanded Dona.
There were bright spots in emptiness which the electron telescope instantly declared to be planets. Kim set up cameras for pictures.
"Alis One is the only really uninhabitable planet in the galaxy that's inhabited," he observed painstakingly. "It belongs to Pharos Three. I understand it's the personal property of the king. It has no atmosphere in spite of an extremely high specific gravity and a reasonable mass. But the plutonium mines have been worked for five thousand years."
"Plutonium mines with that half-life?" Dona said skeptically. "You must be joking!"
"No," said Kim. "It's a very heavy planet, loaded with uranium and stuff from bismuth on out. It has an extremely eccentric orbit. As I told you, at aphelion it's beyond the orbit of Pharos Two. At perihelion, when it's nearest to its sun, it just barely misses Roche's Limit—the limit of nearness a satellite can come to its primary without being torn apart by tidal strains. And at its nearest to its sun, it's bombarded with everything a sun can fling out into space from its millions of tons of disintegrating atoms. Alpha rays, beta rays, gamma particles, neutrons, and everything else pour onto its surface as if it were being bombarded by a cyclotron with a beam the size of a planet's surface. You see what happens?"
Dona looked startled.
"But Kim, every particle of the whole surface would become terrifically radioactive. It would kill a man to land on it!"
"According to my merchant-prince friend on Spicus Five, it did kill the first men to set foot on it. But the point is that its heavy elements have been bombarded, and most of its uranium has gone on over to plutonium and americium and curium. In ancient days, when it went out on the long sweep away from its sun, it cooled off enough for men to land on it at its farthest-out point. With shielded space-suits they were able to mine its substance for four to five months before heat and rising induced radio-activity drove them off again. Then they'd wait for it to cool off once more on its next trip around.
"They went to it with space-ships, and the last space-line in the First Galaxy ran plutonium and americium and the other radioactives to a matter-transmitter from which they could be distributed all over the galaxy. But it wasn't very efficient. They could only mine for four or five months every four years. All their equipment was melted and ruined when they were able to land again. A few hundred years ago, however, they solved the problem."
DONA stared out the vision-ports. Then were two planets which might be tilt one in question. But there were only three an sight.
“How did they solve it?" Dona asked.
“Somebody invented a shield," said Kim as drily as before. "It was a force-field. It has the property of a magnetic field on a conductor with a current in it, except that at acts on mass as such. A current-carrying conductor in a magnetic field tends to move at right angles both to the current and the field. This force-field acts as if mass were an electric charge.
"Anything having mass, entering the field, tries to move sidewise. The faster it moves, the stronger the sidewise impulse. Neutrons, gamma particles, met rays and even electrons have mass. So has light. Everything moving that hits the shielding field moves sidewise to its original course. Radiation from the sun isn't reflected. It's deflected, at right angles.
“So, with the shield up men can stay on the planet when it is less than three diameters from its sun. No heat reaches it. No neutrons. No radiations at all. It doesn't heat up. And that's the answer. For three months in every four-year revolution, they have to keep the shield up all the time. For three months more they keep it up intermittently, flashing it on for fractions of a second at a time, just enough to temper the amount of heat they get.
They live on great platforms of uranium glass, domed in. When they go out mining they wear shielded space-suits and work in shielded machines. The whole trick was worked out about five hundred years ago, they say, and the last space-line went out of existence, because they could use a matter-transmitter for all but six of our months of that planet's year."
"And did you find out how it's done?" asked Dona.
"Hardly," said Kim. "The planet belongs to the king of Pharos Three. Even five hundred years ago the governments of all the planets were quite tight corporations. Naturally Pharos wouldn't let the secret get out. There are other planets so close to their primaries that they're radioactive. If the secret were to be disclosed there'd be competition. There'd be other plutonium mines in operation. So he's managed to keep it to himself. But we've got to find out the trick." There was silence. Kim began to check over the pictures the cameras had taken and developed. He shook his head. Then he stared at a photograph which showed the blue-white dwarf itself. His face looked suddenly very drawn and tired.