"Doc!" he screamed into the mouthpiece in his helmet. "Doc, give me a hand!" Then a cold hand closed over his heart. _The transmitter was off!_ In his horseplay he had not turned the knob, and now his hands were welded to the floor by the crushing weight. He lashed out frantically with his lead-soled feet, for they could still move. He tried to pound the lead soles in the distress code, but the pain of his crushed ribs was telegraphing down his nerves and the rhythm was erratic. _Here it comes_, he thought bleakly, and a black wave curled over his thoughts. He caught his breath and gagged. He looked up into Doc's anxious eyes and pulled the mask that was feeding him oxygen off his face. "Whoosh," he said. "What was that?" "Just plain gravity," replied Doc. "The Stable-G unit just covers the flight-compartment here, as you well know. When you stuck your head into the tunnel, you went over the edge, and the part of you that was in the tunnel must have weighed tons. I had to put a power winch on you to drag you out. Wonder it didn't pull you in two. We'd have thought of that if we both hadn't been trying to be funny." They considered this soberly for some minutes. "Well," said Jon, raising a soothing hand to his aching neck, "that takes care of that. The drive compartment is out of bounds for us until we can get Stable-G into that tunnel." "Yes," said Doc shortly. He turned to the rack where he had been working. He tossed the correlation tapes to Jon. "Read 'em and weep," he said grimly. Jon skimmed the tapes quickly. Twice he went back and checked the cold merciless facts. Finally he looked up and took a deep breath. It was unescapable fact, this asteroid was radio-active. It was only a matter of time until the ship would be contaminated. "How long?" He forced his voice into steadiness. Doc tapped a cigarette alight and took a deep lungful of smoke. He pursed his lips and gazed at the glowing end with deep distaste. "Between three and four days," he said slowly. "Say seventy-two hours to be safe." "Well," said Jon, "let's see about getting this can the hell out of here." He settled himself in his seat and his experienced hands ran smoothly over the multitude of controls. The amber READY light slowly slid through the spectrum until it reached green. Then the red warning lights came on above the firing switches. "Set," he said over his shoulder, and Doc slid into his shock-chair and clicked the switch. "Right," said Doc. Jon flipped the three toggle switches and shoved the red power lever full ahead. The ship quivered, and the tiny shudders of strain telegraphed their way up to Jon's sensitive nerves. But the ship moved not at all. Jon cursed softly and threw the auxiliaries on. The sense of strain grew until it was nearly unbearable. The ship edged ahead, six inches, six more, then the warning lights began to pop on above the control panel. Jon groaned, and cut power. He swiveled around.