“Just as described,” he said aloud. He had read the HOOPSNAKE program many times, had memorized it. “Sever the tubing. With this fine knife supplied by the Shuttle.” He took the knife and sawed through the resistant plastic, cut into it and saw the poisonous granules of uranium isotope inside. “U-235, very deadly.” He smiled when he realized that he was no longer afraid at all. “A remarkable discovery,” he said. “I wish I could tell Colonel Kuznekov about it. Well perhaps I shall, if the Church is right and the Communist Party is wrong. I would like to tell the Colonel that courage is not a unique property of his generation.”

The plastic tubing pulled free easily now. He pulled off the required length as instructed by the program, making sure that the loose end was going through the gap in the shielding. Then he went out after it, pushing it ahead of him, towing it behind as he worked his way around the base of the engine towards the torn-away thrust cone. Droplets of gas, freezing as they emerged, shot out in a steady stream, making a comet's tail behind the ship.

“This could be dangerous now,” he said, working his way around the stream. “It has to be done right, absolutely right the first time.”

As he reached the right spot he looked up, startled, as burning fragments of the ship tore by.

They were into the atmosphere. Just moments left.

Gregor took one second to snap his safety line to the ship. He must be steady now, and would need both hands. The plastic tubing was stiff but bent as he applied pressure, rolling it upon itself, compacting it into a ball he could clasp between his hands, heavy, twenty-five kilos or more. He was aware that he was dead now in more ways than one, that the radiation of the U-235 increased as the mass of metal was brought closer and closer. But not to critical mass, there wasn't enough of it for that. The hydrogen would have to moderate the reaction for that, slow down and trap the particles so that it went critical, became an atomic bomb.

“Yes,” he said, “now is the time.”

Holding the heavy sphere of uranium before him he moved to the engine, looked in. The sun was behind him now, shining into the chamber.

It was breathtaking. The hydrogen had been pumped in steadily for some minutes now. At first it had turned to gas, but in doing so it had chilled down the quartz chamber walls. As more and more hydrogen had poured in it had stopped vaporizing. The chamber was now filled and brimming over with the pale, transparent fluid, two hundred and fifty degrees below zero. As still more was pumped in globules formed at the open end and drifted away, touching Gregor's faceplate and puffing away as gas.

For a long instant he stared into that cold pool — then plunged in the uranium ball. It was heavy and he had to push to accelerate it and it moved firmly from his hand, down the length of the engine. Surrounded by a constantly renewed cloud of gas as the hydrogen boiled when it came near the warm metal. A gas cloud that prevented the liquid hydrogen from coming close enough to moderate the fast particles emerging from the uranium, prevented the chain reaction from starting.

This did not last very long. The metal cooled and the liquid collapsed onto it and touched it.

Strapped down, her body pressing out against the restraint, Coretta saw the shining form of Prometheus grow smaller, shrinking, framed between the gap of the closing doors, visible for one last instant. Then vanished as the doors slammed shut.

“We are at least forty miles from Prometheus,” Cooke said, his voice sounding in all their helmets. “Lifting up and — God…” He was silent for a moment. Then he spoke. “We're facing away. Thank God. You all right back there? A light, an explosion, I have never seen a light like that. It went up. It did. It's not going to impact after all. They're safe back on Earth.”

It was black inside the unlit cargo bay, as dark for Coretta as it was for the blinded pilots.

“Goodbye, Gregor,” she said softly, into the darkness.

44

“Air speed three hundred knots,” Decosta said.

“Looks good,” Cooke said. “I'm making the last turn into the glide path now. Drop the landing gear.”

Decosta threw the switch and watched silently until the green light flicked on. “Gear down and locked.”