It was months later, and he was alone in Echus Chasma, when the robots on Deimos finished their construction, and the starter deuterium ignited the drive engine. One thousand tons of crushed rock were thrown out by the engine every second, at a speed of 200 kilometers per second. All flying out tangent to the orbit and in the orbit plane. In four months, when about a half percent of the moon’s mass had been ejected, the engine would cut off. Deimos would then be 614,287 kilometers away from Mars, according to Sax’s calculations, and on its way completely out of Mars’s influence, to become a free asteroid again.

Now it flew in his night sky, an irregular gray potato, less luminous than Venus or Terra, except that there was a new comet blazing out of its side. Quite a sight. News all over both worlds. Scandalous! Controversial even in the resistance, where people argued pro and con. All that squabbling. Hiroko was going to get tired of it and light out for the territory, he could feel the shape of it. Yes, no, what, where. Who did it? Why?

Ann came on the wrist to ask the same questions, looking furious.

“It was a perfect weapons platform,” Sax said. “If they made it into a military base, like they did Phobos. We would have been helpless under it.”

“So you did this on the off chance it might get turned into a military base?”

“If Arkady and his crew hadn’t fixed Phobos on the off chance, we couldn’t have dealt with it. We would have been killed. Anyway, the Swiss heard it was going to happen.”

Ann was shaking her head, staring at him as if he were mad. A crazed saboteur. Rather a case of the pot calling the kettle black, in his opinion. Resolutely he met the look. When she cut the connection he shrugged and called the Bogdanovists. “The Reds have a catalog of — all the objects in orbit around Mars. Then we need surface-to-space delivery systems. Spencer will help. Equatorial silos. Inactive moholes. Do you understand?”

They said they did. You didn’t have to be a rocket scientist. And so if it ever came to it again, they would not be pounded from space.

Sometime later, he could not be sure how long, Peter appeared on the little screen of the boulder car Sax had borrowed from Desmond. “Sax, I’m in contact with some friends who work on the elevator, and with Deimos accelerating, the cable oscillations to dodge it have been thrown off in their timing. It looks like the next pass in its orbit might collide with the elevator, but my friends can’t get the cable’s navigation AI to respond to them. Apparently it’s really hardened to outside input, to prevent sabotage you know, and the idea of Deimos changing speed is something they can’t get it to accept. Do you have any suggestions?”

“Let it see for itself.”

“What?”

“Feed the data on Deimos into it. It must get that anyway. And it’s programmed to avoid it. Direct its attention to the data. Explain what happened. Trust it.”

“Trust it?”

“Well, talk to it.”

“We’re trying, Sax. But the antisabotage programming is real strong.”

“It’s running the oscillations to avoid Deimos. As long as that’s in its list of goals, you should be okay. Just give it the data.”

“Okay. We’ll try.”

It was night, and Sax went outside. Wandering in the darkness, under the immense cliff of the Great Escarpment, in the region just north of where Kasei Vallis broke through the wall. Sei meant star in Japanese, ka fire. Fire star. It was the same in Chinese, in which huo was the syllable the Japanese pronounced as ka, and hsing, sei. A Chinese word to start with, Huo Hsing: fire star, burning in the sky. They said Ka was what the little red men called it. We live on fire. Sax was distributing seeds in the ground, the hard little nuts pushed just under the surface of the sand flooring the chasm. Johnny Fireseed. There in the southern sky Deimos burned, slowly losing way through the stars, rolling westward at its own slow pace. Now pushed by the pinpoint comet burst on its eastern edge. The elevator rising over Tharsis was invisible, the new Clarke perhaps one of the dimmer stars in the southwest sky, it was impossible to say. He kicked a rock by accident, bent down and planted another seed. After the seeds were all out, there were starter packets of a new lichen to distribute. A chasmoendolithic strain, very hardy, very fast to propagate, very quick to pump out oxygen. Very high surface-to-volume ratio. Very dry.

A bip on the wrist. He switched the voice into his helmet intercom as he continued to take the little nuts out of his thigh pocket and shove them into the sand, careful to avoid damaging the roots of any of the sedges or other ground cover that dotted the ground like furry black rocks.

It was Peter, sounding excited. “Sax, Deimos is coming up on them now, and the AI seems to have acknowledged that it’s not in its usual spot in its orbit. It’s been mulling it over, they say. The attitude jets all through their sector have started a bit early, so we’re hopeful that the system is responding.”

“Can’t you calculate the oscillation?”

“Yes, but the AI is proving recalcitrant. It’s a stubborn bastard, the security programs are pretty watertight. We can just figure out enough from independent calculations to see that it’s going to be a pretty close pass.”

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 Dei-’ mos 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.