His son entered the room, followed by Stein and Alexander Dimitriev, his chief engineer. At his gesture they were seated at the table across from him. "Thomas, Alexander. Now we are come to the hard part: how to detonate safely and accurately. As you know, in this, timing is everything. Everything. If we miss by only a few seconds, we doom the planet to extinction." "Is it true that you intend to remain behind?" said Dimitriev, "and detonate the bombs yourself, from no greater distance than a thousand kilometers?" "Father!" YOU MUST UNDERSTAND, LEON. "Before I say yes or no, let us look at the alternatives. That is why you are here. I must know that you stand behind me." "We could blow them by radio control." His son. "No. With the static storms this heavy and unpredictable, they could detonate too soon, or not at all." "What about a laser-triggered mechanism above ground?" asked Dimitriev. "A fast moving ship could activate it, then be gone." Dobrynin opened his hand toward Stein. "I'm afraid that's not possible," he conceded. "To avoid cloud cover and volcanic discharge the ship would have to fly very high. And the way the upper atmosphere refracts light, even laser is not a sure thing. And also, there is the problem of the gravity beam itself, distorting the path of the ship." Dimitriev turned away. "Alexander, Leon. Listen to me. There is only one other chance that I see, and it is not a good one. We could build the laser-trigger upon a high tower, allowing me to activate it from the ground at a greater distance. But I am not sure we could construct such a tower in time. And also, it would cost more lives." He looked at his son. "Or I could detonate the bombs myself, safely and surely, by cable from Leopold Station. I wish there was another way." "But why does it have to be you? You are needed---" His son broke off. "Who would you have me send instead? I am most qualified, except perhaps for Stein. And this....." He spoke now with difficulty. "This is my home. It is everything I have worked for. If it is lost then I. . .I would not want to live. We have left the mainstream. I do not want to go back." The room was still, and no one spoke. Finally Dimitriev rose and came toward him. He offered him his hand, and Dobrynin took it in both of his own. "Good hunting, Nicholai. I am with you." He turned and left the room. Stein rose also. "I will have an approximate time, and prep the computer, at Leopold before I go..... I think that it is possible." "Thank you, Thomas." The scientist bowed his head and was gone. For a moment father and son stood looking down, and neither spoke. "Why couldn't I do it in your place?" "You have not the skill..... Your mother needs you." "And not you? Will you leave her alone?" "She has always been alone. Forgive me." "Father." He was crying now, ashamed.