 What would have happened if the Centaurus Expedition hadn’t failed?
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. 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. "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.
 People from Earth would have colonized the Procyon system.
 People from Earth would have colonized the Procyon system.  Captain Llud would have become a hero.  The other two Quest ships would have been launched.  Humanity would have died out.