Kemp cut a plug, fitted it into the hole, and welded the seams closed. The tube was sealed. When electric current fired the rocket head, the thorium carrying the plutonium wedge would be driven forward to meet the wedge in the back. And, unless Rip had miscalculated the mass of the two pieces, they would have their nuclear blast. Rip surveyed the crystal with some anxiety. It looked right. Dominico already had rigged the timer from the atomic bomb. He connected the wires. "Do I set it, sir?" "Load the communicator, the extra bomb parts, the rocket launcher and rockets, the cutting equipment, my instruments, and the tubes of fuel," Rip ordered. "Leave everything else in the cave." The Planeteers ran to obey. Rip waited until the landing boat was nearly loaded, then told Dominico to set the timer for five minutes. He wondered how they would explode the second charge, since they had only the one timer left, then forgot about it. Time enough to worry when faced with the problem. "I'll take the snapper-boat," he stated. "Santos in the gunner's seat. Koa in charge in the landing boat. Dowst pilot. Let's show an exhaust." He fitted himself into the tight pilot seat of the snapper-boat while Santos climbed in behind. Then, handling the controls with the skill of long practice, he lifted the tiny fighting rocket above the asteroid and waited for the landing boat. When it joined up, Rip led the way to safety. As he cut his exhaust to wait for the explosion, he sighted past the snapper-boat's nose to the asteroid. Even though both boats had been careful to match velocity with the asteroid as closely as possible, the slight difference remaining caused them to drift sunward. Rip cut his jets in to compensate, and saw Dowst do the same. Another few miles toward the sun, and the landing boat wouldn't have the power to get away from Sol's gravity. A few miles beyond that, even the powerful little snapper-boat would be caught. Below, the timer reached zero. A mighty fan of fire shot into space. The asteroid shuddered from the blast, then swerved gradually, picking up speed as well as new direction. Rip swallowed hard. Now they were committed. They would reach a new perihelion far beyond the limits of safety. _P_ for perihelion and _P_ for peril. In this case, they were the same thing! CHAPTER FOURTEEN Between Two Fires Back on the asteroid, the Planeteers started laying the second atomic charge. Rip selected the spot, found a nearby crystal that would serve to house the bomb, and Kemp started cutting. The Planeteers knew what to do now, and the work went rapidly. Rip kept an eye on his chronometer. According to the message from Terra base, he had about fifteen minutes before the Consops cruiser arrived.