The four of them watched through the ports as the thread of vapor sped upward. They hated the rocket and the people who had built it. Joe said between his teeth, "We could spend our landing-rockets and make it chase us, but it'll have fuel for that!" The Chief muttered in Mohawk. The words sounded as if they ought to have blue fire at their edges and smell of sulphur. Mike the midget said crackling things in his small voice. Haney stared, his eyes burning. Their ship was a little over 400 miles up, now. The rocket was 100 or better. The rendezvous would be probably 200 miles ahead and correspondingly higher. The rocket was accelerating furiously. It had farther to travel, but its rate of climb was already enormous and it increased every second. The ship could swing to right or left on steering rockets, but the war rocket could swerve also. It was controlled from the ground. It did not need to crash the small ship from space. Within a limited number of miles the blast of its atomic warhead would vaporize any substance that could exist. And of course the ship could not turn back. Even the expenditure of all its landing-rockets could not bring twenty tons of ship to a halt. They could speed it up, so it would pass the calculated meeting place ahead of the war rocket. But the bomb would simply follow in a stern chase. In any case, the ship could not stop. But neither could the rocket. Joe never knew how he saw the significance of that fact. On land or sea, of course, an automobile or a ship moves in the direction in which it is pointed. Even an airplane needs to make only minor corrections for air currents which affect it. But an object in space moves on a course which is the sum of all its previous speeds and courses. Joe's ship was moving eastward above the Earth at so many miles per second. If he drove north--at a right angle to his present course--the ship would not cease to move to the east. It would simply move northward in addition to moving east. If the rocket from Earth turned north or east it would continue to move up and merely add the other motion to its vertical rise. Joe stared at the uncoiling thread of vapor which was the murder rocket's trail. He hated it so fiercely that he wanted to escape it even at the cost of destruction, merely to foil its makers. At one moment, he was hardly aware of anything but his own fury and the frantic desire to frustrate the rocket at any cost. The next instant, somehow, he was not angry at all. Because somehow his brain had dredged up the fact that the war rocket could no more turn back than he could--and he saw its meaning. "Mike!" he snapped sharply. "Get set! Report what we do! Everybody set for acceleration! Steering rockets ready, Chief! Get set to help, Haney! I don't know whether we'll get out of this alive, but we'd better get into our space suits."