and of a thousand years, and hissed. They had quarreled so in recent years, mostly about politics. Your plans are all anachronism, Nadia had said. You don’t understand the world. Ha! he had laughed, offended. This world I understand. With an expression as dark as any she had ever seen from him. And she remembered when he had given her the transmitter, how he had cried for John, how crazy he had been with rage and grief. Just in case, he had said to her refusals, pleading. Just in case.
And now it had happened. She couldn’t believe it. She took the box from her walker’s thigh pocket, turned it over in her hand. Phobos shot up over the western horizon like a gray potato. The sun had just set, and the alpenglow was so strong that it looked like she was standing in her own blood, as if she were a creature as small as a cell standing on the corroded wall of her heart, while around her swept the winds of her own dusty plasma. Rockets were landing at the spaceport north of the city. The dusk mirrors gleamed in the western sky like a cluster of evening stars. A busy sky. U.N. ships would soon be descending.
Phobos crossed the sky in four-and-a-quarter hours, so she didn’t have to wait long. It had risen as a half moon, but now it was gibbous, almost full, halfway to the zenith, moving at its steady clip across the coagulating sky. She could make out a faint point of light inside the gray disk: the two little domed craters, Semenov and Leveykin. She held the radio transmitter out and tapped in the ignition code, MANGALA. It was like using a TV remote.
A bright light flared on the leading edge of the little gray disk. The two faint lights went out. The bright light flared even brighter. Could she really perceive the deceleration? Probably not; but it was there.
Phobos was on its way down.
Back inside Cairo, she found that the news had already spread. The flare had been bright enough to catch people’s eyes, and after that they had clumped together around the blank TV screens, by habit, and exchanged rumors and speculation, and somehow the basic fact had gotten around, or been worked out independently. Nadia strolled past group after group, and heard people saying “Phobos has been hit! Phobos has been hit!” And someone laughed, “They brought the Roche limit up to it!”
She thought she was lost in the medina, but almost directly she came to the city offices. Maya was outside: “Hey Nadia!” she cried, “Did you see Phobos?”
“Yes.”
“Roger says when they were up there in year One, they built a system of explosives and rocketry into it! Did Arkady ever tell you about it?”
“Yes.”
They went in to the offices, Maya thinking aloud: “If they manage to slow it down very much, it’ll come down. I wonder if it’ll be possible to calculate where. We’re pretty damn close to the equator right here.”
“It’ll break up, surely, and come down in a lot of places.”
“True. I wonder what Sax thinks.”
They found Sax and Frank bunched before one screen, Yeli and Ann and Simon before another. A UNOMA satellite was tracking Phobos with a telescope, and Sax was measuring the moon’s speed of passage across the Martian landscape to get a fix on its velocity. In the image on the screen Stickney’s dome shone like a Faberge egg, but the eye was drawn away from that to the moon’s leading edge, which was blurry and streaked with white flashes of ejecta and gases. “Look how well balanced the thrust is,” Sax said to no one in particular. “Too sudden a thrust and the whole thing would have shattered. And an unbalanced thrust would have set it spinning, and then the thrust would have pushed it all over the place.”
“I see signs of stabilizing lateral thrusts,” his AI said.
“Attitude jets,” Sax said. “They turned Phobos into a big rocket.”
“They did it in the first year,” Nadia said. She wasn’t sure why she was speaking, she still seemed out of control, observing her actions from several seconds behind. “A lot of the Phobos crew was from rocketry and guidance. They processed the ice veins into liquid oxygen and deuterium, and stored it in lined columns buried in the chondrite. The engines and the control complex were buried centrally.”
“So it is a big rocket.” Sax was nodding as he typed. “Period of Phobos, 27,547 seconds. So it’s going. . 2.146 kilometers per second, approximately, and to bring it down it needs to decelerate to. . to 1.561 kilometers per second.
So, 585 kilometers per second slower. For a mass like Phobos. . wow. That’s a lot of fuel.”
“What’s it down to now?” Frank asked. He was black-faced, his jaw muscles pulsing under the skin like little biceps— furious, Nadia saw, at his inability to predict what would happen next.
“About one point seven. And those big thrusters still burning. It’ll come down. But not in one piece. The descent will break it up, I’m sure.”
“The Roche limit?”
“No, just stress from aerobraking, and with all these empty fuel chambers. . ”
“What happened to the people on it?” Nadia heard herself ask.
“Someone came on and said it sounded like the whole population had bailed out. No one stuck around to try and stop the firing.”
“Good,” Nadia said, sitting down heavily on the couch.
“So when will it come down?” Frank demanded.
Sax blinked. “Impossible to say. Depends on when it breaks up, and how. But pretty soon, I’d guess. Within a day. And then there’ll be a stretch somewhere along the equator, probably a big stretch of it, in big trouble. It’s going to make a fairly large meteor shower.”
“That will clear away some of the elevator cable,” Simon said weakly. He was sitting beside Ann, watching her with concern. She stared at Simon’s screen bleakly, showed no sign of hearing any of them. There never had been word of their son Peter. Was that better or worse than a soot pile, a dotcode name coming up on your wristpad? Better, Nadia decided. But still hard.
“Look,” Sax said, “it’s breaking up.”
The satellite telescopic camera gave them an excellent view. The dome over Stickney burst outward in great shards and the crater pit lines that had always marked Phobos suddenly puffed with dust, yawning open. Then the little potato-shaped world blossomed, fell apart into a scattering of irregular chunks. A half a dozen large ones slowly spread out, the largest one leading the way. One chunk flew off to the side, apparently powered still by one of the rockets that had lain buried in the moon’s interior. The rest of the rocks began to spread out in an irregular line, tumbling each at a different speed.
“Well, we’re kind of in the line of fire,” Sax remarked, looking up at the rest of them. “The biggest chunks will hit the upper atmosphere soon, and then it’ll happen pretty quickly.”
“Can you determine where?”
“No, there’s too many unknowns. Along the equator, that’s all. We’re probably far enough south to miss most of it, but there may be quite a scatter effect.”
“People on the equator ought to head north or south,” Maya said.
“They probably know that. Anyway the fall of the cable probably cleared the area pretty effectively already.”
There was little to do but wait. None of them wanted to leave the city and head south, it seemed they were past that kind of effort, too hardened or too tired to worry about longshot risks. Frank paced the room, his swarthy face working with anger; finally he couldn’t stand it, and got back on his screen to send off a sequence of short pungent messages. One came back in, and he snorted. “We’ve got a grace period, because the U.N. police are afraid to come down here until after the shit falls. After that they’ll be on us like hawks. They’re claiming that the command initiating the Phobos explosions originated here, and they’re tired of a neutral city being used as a command center for the insurrection.”
“So we’ve got until the fall is over,” Sax said.
He clicked into the UNOMA network, and got a radar composite of the fragments. After that there was nothing to do. They sat; they stood and walked around; they looked at the screens; they ate cold pizza; they napped. Nadia did none of these things. She could only manage to sit, hunched over her stomach, which felt like an iron walnut in her. She waited.
Near midnight and the timeslip, something on the screens caught Sax’s attention, and with some furious typing on Frank’s channels he got through to the Olympus Mons observatory. It was just before dawn there, still
