Sax straightened up and tapped out calculations of his own on his wristpad. Orbital period of Deimos had started at approximately 109,077 seconds. The drive engine had been on for some, he wasn’t sure, say a million seconds, speeding the moonlet by a significant amount already, but also expanding the radius of its orbit. . . . He tapped away in the great silence. Usually when Deimos passed by the elevator cable, the cable was at the full extension of its oscillation in that sector, some fifty kilometers or more away, far enough away that the gravitational perturbation was so small it did not have to be factored into the adjustments of the cable jets. This time the acceleration and movement outward of Deimos would throw the timing off; the cable would be moving back in toward Deimos’s orbital plane too soon. So it was a matter of slowing the Clarke oscillation, and adjusting for that all up and down the cable. Complicated stuff, and no wonder the AI was not able to display what it was doing in much detail. It was likely to be busy linking up to other AIs to gain the calculating capacity necessary to perform the operation. The shapes of the situation— Mars, the cable, Clarke, Deimos— were beautiful to contemplate.

“Okay, here it comes at them,” Peter said.

“Are your friends at the elevation of the orbit?” Sax asked, surprised.

“They’re a couple hundred kilometers below it, but their elevator car is on its way up. They’ve linked me up to their cameras, and hey, here it comes . . . Yes! Oh! Ka wow, Sax, it must have missed the cable by about three kilometers! It just flashed right by their camera!”

“A miss is as good as a mile.”

“What’s that?”

“At least in a vacuum it is.” But now it was more than just a passing rock. “What about the tail of ejecta from the drive engine?”

“I’ll ask. . . . They ended up crossing in front of Deimos, they say.”

“Good.” Sax clicked off. Good foresight on the AI’s part. A few more passes and Deimos would be above Clarke, and the cable would no longer have to dodge it. Meanwhile, as long as the navigational AI believed in the danger, as obviously it did now, they would be okay.

Sax was of two minds about this. Desmond had said he would be happy to see the cable come down again. But there were few who seemed to agree with him. Sax had decided against taking unilateral action on the matter, since he was not sure what he felt about that tie to Earth. Best to limit unilateral action to things he was sure about. And so he bent over and planted another seed.

Part 9: The Spur of the Moment

Part Nine

The Spur of the Moment

Prologue