Rip didn’t know what to say, so he kept still. But sharp anger was rising inside of him. O’Brine went on, "Instructions say I’m to hand you your orders enroute. They don’t say when. I’ll decide that. Until I do decide, I have a job for you and your men. Do you know anything about nuclear physics?" Rip’s eyes narrowed. He said cautiously, "A little, sir." "I’ll assume you know nothing. Foster, the designation SCN means Space Cruiser, Nuclear. This ship is powered by a nuclear reactor. In other words, an atomic pile. You’ve heard of one?" Rip controlled his voice, but his red hair stood on end with anger. O’Brine was being deliberately insulting. This was stuff any new Planeteer recruit knew. "I’ve heard, sir." "Fine. It’s more than I had expected. Well, Foster, a nuclear reactor produces heat. Great heat. We use that heat to turn a chemical called methane into its component parts. Methane is known as marsh gas, Foster. I wouldn’t expect a Planeteer to know that. It is composed of carbon and hydrogen. When we pump it into the heat coils of the reactor, it breaks down and creates a gas that burns and drives us through space. But that isn’t all it does." [Illustration: "You’re a Planeteer. I Don’t Like Planeteers."] "You’re a Planeteer. I Don’t Like Planeteers." Rip had an idea what was coming, and he didn’t like it. Nor did he like Commander O’Brine. It was not until much later that he learned that O’Brine had been on his way to Terra to see his family for the first time in four years when the cruiser’s orders were changed. To the commander, whose assignments had been made necessary by the needs of the Special Order Squadrons, it was too much. So he took his disappointment out on the nearest Planeteer, who happened to be Rip. "The gases go through tubes," O’Brine went on. "A little nuclear material also leaks into the tubes. The tubes get coated with carbon, Foster. They also get coated with nuclear fuel. We use thorium. Thorium is radioactive. I won’t give you a lecture on radioactivity, Foster. But thorium mostly gives off the kind of radiation known as alpha particles. Alpha is not dangerous unless breathed or eaten. It won’t go through clothes or skin. But when mixed with fine carbon, thorium alpha contamination makes a mess. It’s a dirty mess, Foster. So dirty that I don’t want my spacemen to fool with it. "I want you to take care of it instead," O’Brine said. "You and your men. The deputy commander will assign you to a squadroom. Settle in, then draw equipment from the supply room and get going. When I want to talk to you again, I’ll call for you. Now blast off, Lieutenant, and rake that radiation. Rake it clean." Rip forced a bright and friendly smile. "Yes, sir," he said sweetly. "We’ll rake it so clean you can see your face in it, sir." He paused, then added politely, "If you don’t mind looking at your face, sir—to see how clean the tubes are, I mean." Rip turned and got out of there.