An asteroid man has to be able to do the same thing. The human mind is capable of it, and one thing that the men and women of the Belt Cities had learned was to use the human mind. "Looks like a big 'un, Jack," said the instrument man. His eyes were on the radar screen. It not only gave him a picture of the body of the slowly spinning mountain, but the distance and the angular and radial velocities. A duplicate of the instrument gave the same information to the pilot. The asteroid was fairly large as such planetary debris went--some five hundred meters in diameter, with a mass of around one hundred seventy-four million metric tons. * * * * * Within twenty meters of the surface of the great mountain of stone, the pilot brought the ship to a dead stop in relation to that surface. "Looks like she's got a nice spin on her," he said. "We'll see." He waited for what he knew would appear somewhere near the equator of the slowly revolving mass. It did. A silvery splash of paint that had originally been squirted on by the anchor man who had first spotted the asteroid in order to check the rotational velocity. The pilot of the space tug waited until the blotch was centered in the crosshairs of his peeper and then punched the timer. When it came around again, he would be able to compute the angular momentum of the gigantic rock. "Where's he got his anchor set?" the pilot asked his instrument man. "The beep's from the North Pole," the instrument man reported instantly. "How's her spin?" "Wait a bit. The spot hasn't come round again yet. Looks like we'll have some fun with her, though." He kept three stars fixed carefully in his spotters to make sure he didn't drift enough to throw his calculations off. And waited. Meanwhile, the instrument man abandoned his radar panel and turned to the locker where his vacuum suit waited at the ready. By the time the pilot had seen the splotch of silver come round again and timed it, the instrument man was ready in his vacuum suit. "Sixteen minutes, forty seconds," the pilot reported. "Angular momentum one point one times ten to the twenty-first gram centimeters squared per second." "So we play Ride 'Em Cowboy," the instrument man said "I'm evacuating. Tell me when." He had already poised his finger over the switch that would pull the air from his compartments, which had been sealed off from the pilot's compartment when the timing had started. "Start the pump," said the pilot. The switch was pressed, and the pumps began to evacuate the air from the compartment. At the same time, the pilot jockeyed the ship to a position over the north pole of the asteroid. "Over" isn't quite the right word. "Next to" is not much better, but at least it has no implied up-and-down orientation. The surface gravity of the asteroid was only two millionths of a Standard Gee, which is hardly enough to give any noticeable impression to the human nervous system.