Rip watched for a while longer, then wandered back to Commander O'Brine. He was getting anxious. At first the task of capturing an asteroid and moving it back to Earth had been rather unreal, like some of the problems he had worked out while training on the space platform. Now he was no longer calm about it. He had faith in the Terra base Planeteer specialists, but they couldn't figure out everything for him. Most of the problems of getting the asteroid back to Earth would have to be solved by Lt. Richard Ingalls Peter Foster. A junior space officer suddenly called, "Sir, I have a reading at two-seventy degrees, twenty-three degrees eight minutes high." Commander O'Brine jumped up so fast that the action shot him to the ceiling. He kicked down again and leaned over the officer's 'scope. Rip got there by pulling himself right across the top of the chart table. The green point of light on the 'scope was bigger than any other he had seen. "It's about the right size," O'Brine said. There was excitement in his voice. "Correct course. Let's take a look at it." All hands gripped something with which to steady themselves as the cruiser spun swiftly onto the new course. The control officer called, "I have it centered, sir. We'll reach it in about an hour at this speed." "Jack it up," O'Brine ordered. "Heave some neutrons into it. Double speed, then decelerate to reach it in thirty minutes." The control officer issued orders to the engine control room. In a moment acceleration plucked at them. O'Brine motioned to Rip. "Come on, Foster. Let's see what Analysis makes of this rock." Rip followed the commander to the deck below, where the technical analysts were located. His heart was pounding a little faster than usual, and not from acceleration, either. He found himself wetting his lips frequently and thought, _Get hold of it, boy. You've got nothing to worry about but high vacuum._ He didn't really believe it. There would be plenty to worry about. Like detonating nuclear bombs and trying to figure their blast reaction. Like figuring out the course that would take them closest to the sun without pulling them into it. Like a thousand things--all of them up to him. The chief analyst greeted them. "We got the orders to change course, Commander. That gave us the location of the asteroid. We're already working on it." "Anything yet?" "No, sir. We'll have the albedo measurement in a few minutes. It'll take longer to figure the mass." The asteroid's efficiency in reflecting sunlight was its albedo. The efficiency depended on the material of which it was made. The albedo of pure metallic thorium was known. If the asteroid's albedo matched it, that would be one piece of evidence. In the same way, the mass of thorium was known. The measurements of the asteroid were being taken. They would be compared with a chunk of thorium of the same size. If it worked out, that would be evidence enough.