The ship stirred. It swept forward in a swift smooth acceleration that was invincibly convincing of power. The Arnina dwindled swiftly, behind. And Freddy, with compressed lips, touched controls here, and there, and the monstrous ship obeyed with the docility of a willing, well-trained animal. It swept back to clear sight of the Arnina.
“I would say,” said Bridges in a shaking voice, “that it works. The Patrol has nothing like this!”
“No,” said Freddy shortly. His voice sounded sick. “Not like this! It’s a sweet ship. I’m going to hook in the gyro controls. They ought to work. The creatures who made this didn’t use them. I don’t know why. But they didn’t.”
He cut off everything but the lights. He bent down and looked in the compact little aluminum device which would control the flow of nitrogen to the port and starboard drive tubes.
Freddy came back to the control board and threw in the drive once more. And the gyro control worked. It should. After all, the tool work of a Space Patrol machinist should be good. Freddy tested it thoroughly. He set it on a certain fine adjustment. He threw three switches. Then he picked up one tiny kit he had prepared.
“Come along,” he said tiredly. “Our work’s over. We go back to the Arnina and I probably get lynched.”
Bridges, bewildered, followed him to the spidery little spaceboat. They cast off from the huge ship, now three miles or more from the Arnina and untenanted save its own monstrous crew us suspended animation The Space Patrol cruiser shifted position to draw near and pick them up. And Freddy said hardly:
“Remember the Ethical Equations, Bridges? I said they gave me the answer to that other ship’s drive. If they were right, it couldn’t have been anything else. Now I’m going to find out about something else.”
His spacegloved hands worked clumsily. From the tiny kit he spilled out a single small object. He plopped it into something from a chest in the spaceboat—a mortar shell, as Bridges saw incredulously. He dropped that into the muzzle of a line-mortar the spaceboat carried as a matter of course. He jerked the lanyard. The mortar flamed. Expanding gases beat at the spacesuits of the men. A tiny, glowing, crimson spark sped toward outer space. Seconds passed. Three. Four. Five—
“Apparently I’m a fool,” said Freddy, in the grimmest voice Bridges had ever heard.
But then there was light. And such light! Where the dwindling red spark of a tracer mortar shell had sped toward infinitely distant stars, there was suddenly an explosion of such incredible violence as even the proving-grounds of the Space Patrol had never known. There was no sound in empty space. There was no substance to be heated to incandescence other than that of a half-pound tracer shell. But there was a flare of bluewhite light and a crash of such violent static that Bridges was deafened by it. Even through the glass of his helmet he felt a flash of savage heat. Then there was—nothing.
“What was that?” said Bridges, shaken.
“The Ethical Equations,” said Freddy. “Apparently I’m not the fool I thought—”
The Arnina slid up alongside the little spaceboat. Freddy did not alight. He moved the boat over to its cradle and plugged in his communicator set. He talked over that set with his helmet phone, not radiating a signal that Bridges could pick up. In three minutes or so the great lock opened and four spacesuited figures came out. One wore the crested four-communicator helmet which only the skipper of a cruiser wears when in command of a landing party. The newcomers to the outside of the Arnina’s hull crowded into the little spaceboat. Freddy’s voice sounded again in the headphones, grim and cold.
“I’ve some more shells, sir. They’re tracer shells which have been in the work boat for eight days. They’re not quite as cold as the ship, yonder—that’s had two thousand years to cool off in—but they’re cold. I figure they’re not over eight or ten degrees absolute. And here are the bits of material from the other ship. You can touch them. Our spacesuits are as nearly nonconductive of heat as anything could be. You won’t warm them if you hold them in your hand.”
The skipper—Bridges could see him—looked at the scraps of metal Freddy held out to him. They were morsels of iron and other material from the alien ship. By the cold glare of a handlight the skipper thrust one into the threaded hollow at the nose of a mortar shell into which a line-end is screwed when a line is to be thrown. The skipper himself dropped in the mortar shell and fired it. Again a racing, receding speck of red in emptiness. And a second terrible, atomic blast.
The skipper’s voice in the headphones:
“How much more of the stuff did you bring away?”
“Three more pieces, sir,” said Freddy’s voice, very steady now. “You see how it happens, sir. They’re isotopes we don’t have on Earth. And we don’t have them because in contact with other isotopes at normal temperatures, they’re unstable. They go off. Here we dropped them into the mortar shells and nothing happened, because both isotopes were cold—down to the temperature of liquid helium, or nearly. But there’s a tracer compound in the shells, and it burns as they fly away. The shell grows warm. And when either isotope, in contact with the other, is as warm as … say …liquid hydrogen … why … they destroy each other. The ship yonder is of the same material. Its mass is about a hundred thousand Ions. Except for the aluminum and maybe one or two other elements that also are non-isotopic and the same in both ships, every bit of that ship will blast off if it comes in contact with matter from this solar system above ten or twelve degrees absolute.”
“Shoot the other samples away,” said the’ skipper harshly. “We want to be sure—”
There were three violent puffs of gases expanding into empty space. There were three incredible blue-white flames in the void. There was silence. Then—
“That thing has to be destroyed,” said the skipper, heavily. “We couldn’t set it down anywhere, and its crew might wake up anyhow, at any moment. We haven’t anything that could fight it, and if it tried to land on Earth—”
The alien monster, drifting aimlessly in the void, suddenly moved. Thin flames came from the gill-like openings at the bow. Then one side jetted more strongly. It swung about, steadied, and swept forward with a terrifying smooth acceleration. It built up speed vastly more swiftly than any Earth-ship could possibly do. It dwindled to a speck. It vanished in empty space.
But it was not bound inward toward the sun. It was not headed for the plainly visible half-moon disk of Jupiter, now barely seventy million miles away. It headed out toward the stars.
“I wasn’t sure until a few minutes ago,” said Freddy Holmes unsteadily, “but by the Ethical Equations something like that was probable. I couldn’t make certain until we’d gotten everything possible from it, and until I had everything arranged. But I was worried from the first. The Ethical Equations made it pretty certain that if we did the wrong thing we’d suffer for it … and by we I mean the whole Earth, because any visitor from beyond the stars would be bound to affect the whole human race.” His voice wavered a little. “It was hard to figure out what we ought to do. If one of our ships had been in the same fix, though, we’d have hoped for—friendliness. We’d hope for fuel, maybe, and help in starting back home. But this ship was a warship, and we’d have been helpless to fight it. It would have been hard to be friendly. Yet, according to the Ethical Equations, if we wanted our first contact with an alien civilization to be of benefit to us, it was up to us to get it started back home with plenty of fuel.”
“You mean,” said the skipper, incredulously, “you mean you—”