 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. If success comes there, a century will have passed before we can return to Earth; friends, relatives, all the generation that launched the Quest ships will be long since dead. "One week since we passed close enough to Aldebaran to ascertain that that system, too, is devoid of planets. "We face the unpleasant realization that what was feared is probably true—that worlds such as the Sun's are a rare accident, and that we may complete our search without finding even one new Earth. "It makes no difference, of course; we cannot betray the plan.... This may be man's last chance of escaping his pitiful limitation to one world in all the Universe. Certainly the building of this ship and its two sisters, the immense expenditure of time and labor and energy stores that went into them, left Earth's economy drained and exhausted. Only once in a long age does mankind rise to such a selfless and transcendent effort—the effort of Egypt that built the pyramids, or the war efforts of the nations in the last great conflicts of the twentieth century. In any case, it would be impossible to transport very many people to other stars; but Earth could at least go into its decline with the knowledge that its race went onward and upward, expanding limitlessly into the Universe.... "Hopeless, unless we find planets!" It would be a one-way journey—even if enough fuel remained, there would be little point in returning to Earth after more than forty thousand years. By then our civilization certainly, and perhaps the human race itself, would have perished from memory. "That was why the planners limited our voyage, and those of the other Quests , to less than a thousand years Earth time. Why not forget about Earth and go on to Omega Centauri?
 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.