 Of the following, which is the best plausible explanation for the behavior of the Earthen ships?
[Transcriber's Note: This etext was produced from Planet Stories Fall 1949. In the last hours the star ahead had grown brighter by many magnitudes, and had changed its color from a dazzling blue through white to the normal yellow, of a GO sun. That was the Doppler effect as the star's radial velocity changed relative to the Quest III , as for forty hours the ship had decelerated. It was a subdued excitement; men and women, they came and stood quietly gazing into the big vision screens that showed the oncoming star, and there were wide-eyed children who had been born in the ship and had never seen a planet. The great chamber, a full cross-section of the vessel, had been at first a fuel hold. At the voyage's beginning eighty per cent of the fifteen-hundred-foot cylinder had been engines and fuel; but as the immense stores were spent and the holds became radioactively safe, the crew had spread out from its original cramped quarters. Earth's still there." He said, with a touch of tolerant amusement, "What did you think might have happened to Earth? He had already set up on the calculator a course that would carry them to Earth. And we don't know what changes have taken place on Earth. From his private office-cabin, he sent a message to Chief Astronomer Zost Relyul to notify him as soon as Earth's surface features became clear; then he sat idle, alone with his thoughts. Perhaps, he thought, he was feeling the weight of his nine hundred Earth years—though physically he was only forty now, ten years older than when the voyage had begun. That was the foreshortening along the time axis of a space ship approaching the speed of light. He might add that to the ship's official log and its collections of scientific data, as a report to whatever powers might be on Earth now—if such powers were still interested. "One light-day out from Procyon, the thirty-third day by ship's time since leaving Earth. "Our visit to Procyon drew a blank. There is only one huge planet, twice the size of Jupiter, and like Jupiter utterly unfit to support a colony. "Our hopes were dashed—and I think all of us, even remembering the Centaurus Expedition's failure, hoped more than we cared to admit. If Procyon had possessed a habitable planet, we could have returned after an absence of not much over twenty years Earth time.
 900 years passed on Earth. The populations were different enough that the Quest III Earthens scared the current Earthen population.
 Since the Quest III trip promised to locate more planets, the current Earthens didn't trust them when they learned of their success because of how unlikely it was.  Since the Quest III trip promised to locate more planets, the current Earthens didn't trust them when they learned of their failure.  Since the Quest III trip promised to locate more natural resources, the current Earthens didn't trust them when they learned of their failure.  900 years passed on Earth. The populations were different enough that the Quest III Earthens scared the current Earthen population.