“There are times,” said Kresh, “when I could do without either of them, or any of this.”

Neither of them spoke as Donald brought the aircar into a smooth landing in front of the Terraforming Center.

KRESH, FREDDA, AND Donald walked into Room 103 at the Terraforming Center and took their accustomed places at the console nearest to Dee. Their division of labor was straightforward. Kresh worked through the endless sequence of decisions large and small presented to him by Unit Dee.

Fredda monitored Unit Dee’s performance and behavior, and consulted with Soggdon and the other experts on the subject. Thus far, Dee’s level of First Law stress was remarkably low-indeed, alarmingly low.

Fredda had another job as well. In order to preserve the fiction that Inferno was a simulation, and Governor Kresh merely a simulant, he could not have any direct communication with any of the Terraforming Center staff whenever it was possible that Dee could overhear. Fredda served as an anonymous intermediary, passing information back and forth, mostly via scribbled notes and whispers.

Donald, meantime, was in constant hyperwave contact with Kresh’s office back in Hades. He used preexisting and standing orders to handle most of the queries and requests, and bucked whatever decisions he had to up to Kresh when he needed to do so.

Kresh sat down at the console with something very close to dread. All would be in readiness soon, and the clock was running out. They were getting close, very close, to the moment when he would be forced to make the final, irrevocable decision. He glanced at the wall chronometer. It was set in countdown mode, showing the time left until the comet diversion maneuver. Ninety-four hours left. Before that clock reached zero, he would have to decide whether to send the comet toward Utopia-or to turn his back on all of it, walk away from all the madness and chaos that had led them to this place. He had thought he was sure, that he was ready, that he was ready to step forward. But by now all the pressures were pushing him forward, urging him onward. Suppose, just suppose, that he now concluded the comet diversion would be a dreadful mistake? Would he have the courage to say no, to stop, to let it go past?

“Good morning, Governor Kresh,” said Unit Dee the moment Kresh put on the headset.

“Good morning, Dee,” he replied, his voice gruff and not at all at ease. “What have you and Dum got for us this morning?”

“Quite a number of things, sir, as you might imagine. However, there is one point in particular that I thought we might discuss at once.”

Kresh leaned back in his chair and rubbed the bridge of his nose. It was not going to be an easy day. “And what might that be?” he asked.

“A plan that, if you forgive the expression, I have named ‘Last Ditch. ‘ It provides you with an abort option for the comet impact long after its diversion. Dum performed most of the calculations, and only finished a very few minutes ago.”

“How the devil can we abort after the diversion?” Kresh demanded.

“As you know, the whole body of the comet has been rigged with explosive charges, intended to break the comet up into the desired number of fragments just before impact.”

“What of it?”

“Virtually all of those explosive charges have been damped down, or directionalized in one way or another, mostly by means of shaped forcefields. The plan is for these controlled charges to be set off one at a time in a very carefully planned sequence, so as to limit undesired fragmentation and lateral spread. By shutting down all the damping and directionalization, and by detonating all of the explosives in a different order, and much more rapidly, it should be possible to disintegrate the entire comet, reducing it to a cloud of rubble.”

“But the whole cloud of rubble will still be headed right for the planet,” Kresh objected. “It will all hit the planet, in a whole series of uncontrolled impacts.”

“That is not quite correct, Governor. If the blasts are done in the right way, and far enough before the impact, the explosion will give the vast majority of the material a large enough lateral velocity that it will miss the planet completely. Our model shows that, even in a worst case scenario, over ninety percent of the comet debris will miss the planet and continue on in its orbit about the sun. Of the ten percent or so of the debris that does strike the planet, ninety percent will strike in areas already slated for evacuation, or in the open waters of the Southern Ocean.

“That still leaves something like one percent of the comet coming down in uncontrolled impacts,” Kresh said.

“And some areas will experience a brief period of increased danger,” Dee replied. “Small pieces of debris will fall all over the planet, for about 32 hours after detonation-however, the impact danger for most inhabited regions will be on the order of one strike per hundred square kilometers. Persons in most areas would be in more danger of being struck by lightning in a storm than by being hit a piece of comet debris.”

“But some areas will be more trouble,” Kresh suggested.

“Yes, sir. The closer one gets to the initial target area, the higher the concentration of impacts. However, all the persons in such areas are to have taken shelter as a precaution in any event. If those plans are followed, I would estimate something on the order of one impact per square kilometer in the populated areas of maximum danger-and most of those strikes corning from objects massing under one kilogram.”

Kresh thought for a moment. “How late?” he asked. “What’s the last possible moment you could detonate the comet?”

“In order to stay within the parameters I have described, I would have to perform the explosion no later than ninety-two minutes, fifteen seconds before the scheduled impact.”

“Not bad, Dee,” said Kresh. “Not at all bad.”

Fredda and Soggdon were both listening in on their own headphones, alarmed looks on their faces. Fredda signaled him to cut the mike with an urgent throat-cutting gesture. Soggdon nodded and made the same gesture.

“Just a moment, Dee,” Kresh said. “I want to think about this for a minute. I’ll be right back.”

“Very good, sir,” Dee said.

Kresh cut his mike and took his headset off. “What’s the problem?” he asked. “Why does that idea worry you two so much? I have to admit it sounds pretty damned tempting to me. It gives us a lot more room to maneuver.”

“That’s not the point,” Fredda said. “That’s a robot talking. A robot casually talking about dropping thousands meteorites on the planet at random!”

“But even with fifty thousand-a hundred thousand meteorites-the odds against significant danger to a human being are-”

“Tremendous,” said Donald. Only a First Law imperative could have made him dare to interrupt the planetary governor. “They are unacceptably high. And I would venture to add that any sane Three-Law robot would endeavor to protect a human in danger of being struck by lightning. That level of danger is not negligible.”

“Not to a robot it isn’t,” Fredda agreed. “Or at least it shouldn’t be. To a human, yes, but not a robot.”

“Hold it,” said Kresh. “You’re upset because Dee isn’t overreacting to danger?”

“No,” said Fredda. “I’m upset because this makes me question Dee’s sanity. A robot would have to be on the verge of becoming completely unbalanced to even suggest something that might cause widespread, uncontrolled danger to humans.”

Kresh looked toward Soggdon. “Your opinion, Doctor?”

“I’m afraid I’d have to agree with Dr. Leving,” she said. “But what I find troubling is that all our reading and indicators show Dee’s level of First Law stress has been well within normal range right along. She ought to be flirting with the maximum tolerance levels, given the operations she’s dealing with. And yet, if anything, her readings are a little in the low range.”