 What was Knof Junior’s plan to defeat the attackers?
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. Knof Llud, the Quest III's captain, came slowly down the narrow stair from the observatory, into the big rotunda that was now the main recreation room, where most of the people gathered. 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. Eyes lifted from the vision screens to interrogate Knof Llud; he met them with an impassive countenance, and announced quietly, "We've sighted Earth." As the Quest III's fuel stores and the hope of success in man's mightiest venture had dwindled, so the strength had gone out of him. 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. Presently Knof Llud switched off that younger voice of his and leaned back, an ironic smile touching his lips. "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.
 Wait for the attackers to make a mistake in anger
 Talk to the attackers  Replenish with fresh crew to fight  Wait for the attackers to make a mistake in anger  Release the gravity impulses