It was not until he reached the last spool of microfilm that his situation was forcibly brought to focus in his mind. Thus far, he had thought only about saving himself. But the note at the end of the spool made him realize that there were others to save. The note said: _These reports must reach Earth before 22 June 2287. After that, it will be too late._ _22 June!_ That was--let's see.... _This is the eighteenth of September_, he thought, _June of next year is--nine months away. Surely I can make it in that time. I've got to._ The only question was, how fast was the hulk of the _Shane_ moving? It took him three days to get the answer accurately. He knew the strength of the field around the ship, and he knew the approximate thrust of the single engine by that time. He had also measured the motions of some of the nearer stars. Thank heaven he was a navigator and not a mechanic or something! At least he knew the direction and distance to Earth, and he knew the distance of the brighter stars from where the ship was. He had two checks to use, then. Star motion against engine thrust and field strength. He checked them. And rechecked them. And hated the answer. He would arrive in the vicinity of Sol some time in late July--a full month too late. What could he do? Increase the output of the engine? No. It was doing the best it could now. Even shutting off the lights wouldn't help anything; they were a microscopic drain on that engine. He tried to think, tried to reason out a solution, but nothing would come. He found time to curse the fool who had decided the shielding on the lifeboat would have to be removed and repaired. That little craft, with its lighter mass and more powerful field concentration, could make the trip in ten days. The only trouble was that ten days in that radiation hell would be impossible. He'd be a very well-preserved corpse in half that time, and there'd be no one aboard to guide her. Maybe he could get one of the other engines going! Sure. He _must_ be able to get one more going, somehow. Anything to cut down on that time! He went back to the engines again, looking them over carefully. He went over them again. Not a single one could be repaired at all. Then he rechecked his velocity figures, hoping against hope that he'd made a mistake somewhere, dropped a decimal point or forgotten to divide by two. Anything. Anything! But there was nothing. His figures had been accurate the first time. For a while, he just gave up. All he could think of was the terrible blaze of heat that would wipe out Earth when the Rats set off the sun. Man might survive. There were colonies that the Rats didn't know about. But they'd find them eventually. Without Earth, the race would be set back five hundred--maybe five thousand--years. The Rats would would have plenty of time to hunt them out and destroy them.