The slower robots arrived, bringing an array of explosives left over from the excavation of the town’s foundation. Nadia went to work programming the vehicles to tunnel into the bottom of the cliff, and for most of an hour she was lost to the world. When she was finished she said, “Let’s get back to town and get everyone evacuated. I can’t be sure how much of the cliff might come down, and we don’t want to bury everyone. We’ve got four hours.”
“Jesus, Nadia!”
“Four hours.” She typed in the last command and started up their rover. Angela and Sam followed with a cheer.
“You don’t seem very sorry to leave,” Yeli said to them.
“Hell, it was boring!” Angela said.
“I don’t think that’s going to be much of a problem anymore.”
The evacuation was difficult. A lot of the town’s occupants didn’t want to leave, and there was barely room for them in the rovers at hand. Finally they were all stuffed into one vehicle or another, and off on the transponder road to Burroughs. Lasswitz was empty. Nadia spent an hour trying to contact Phyllis by satellite phone, but the comm channels were disrupted by what sounded like a number of different jamming efforts. Nadia left a message on the satellite itself: “We’re noncombatants in Syrtis Major, trying to stop the Lasswitz aquifer from flooding Burroughs. So leave us alone!” A surrender of sorts.
Nadia and Sasha and Yeli were joined in their rover by Angela and Sam, and they drove up the steep switchbacks of the cliff road, onto the south rim of Arena Canyon. Across from them was the imposing north wall; below to the left lay the town, looking almost normal; but to the right it was clear something was wrong. The water station was broken in the middle by a thick white geyser, which plumed like a broken fire hydrant, and then fell into a jumble of dirty red-white ice blocks. This weird mass shifted even as they watched, briefly exposing black flowing water which frost-steamed madly, white mists pouring out of the black cracks and then whipping down-canyon on the wind. The rock and fines of the Martian surface were so dehydrated that when water splashed onto them they seemed to explode in violent chemical reactions, so when the water ran over dry ground, great clouds of dust fired off into the air and joined the frost steam swirling off the water.
“Sax will be pleased,” Nadia said grimly.
At the appointed hour, four plumes of smoke shot out of the base of the northern wall. For several seconds nothing else happened, and the observers groaned. Then the cliff face jerked, and the rock of the overhang slipped down, slowly and majestically. Thick clouds of smoke shot up from the bottom of the cliff, and then sheets of ejecta shot out, like water from under a calving iceberg. A low roar shook their rover, and Nadia cautiously backed it away from the south rim. Just before a massive cloud of dust cut off their view, they saw the water station covered by the swift tumbling edge of the landslide.
Angela and Sam had been cheering. “How will we tell if it’s worked?” Sasha asked.
“Wait till we can see it again,” Nadia said. “Hopefully the flood downstream will have gone white. No more open water, no more movement.”
Sasha nodded. They sat looking down into the ancient canyon, waiting. Nadia’s mind was mostly blank; the thoughts that did occur to her were bleak. She needed more action like the last few hours’, the kind of intense activity that gave her no time to think; even a moment’s pause and the whole miserable situation crashed back in on her, the wrecked cities, the dead everywhere, Arkady’s disappearance. And no one in control, apparently. No plan to any of it. Police troops were wrecking towns to stop the rebellion, and rebels were wrecking towns to keep the rebellion alive. It would end with everything destroyed, her whole life’s work blown up before her eyes; and for no reason! No reason at all.
She couldn’t afford to think. Down there a landslide had overrun a water station, hopefully, and the water rushing up the well had been blocked and frozen, making a composite dam. After that it was hard to say. If the hydrostatic pressure in the aquifer was high enough, a new breakout might be forced. But if the dam were thick enough. . . Well, nothing to be done about it. Although if they could create some kind of escape valve, to take the pressure off the landslide dam . . .
Slowly the wind tattered the dust away. Her companions cheered; the water station was gone, covered by a fresh black landslide that spilled out from the northern wall, which now had a big new arc in its rim. But it had been a close thing, not anywhere near as big a landslide as she would have hoped. Lasswitz itself was still there, and it appeared that the layer of rock over the water station was not all that thick. The flood seemed to have stopped, it was true; it was motionless, a chunky, dirty white swath, like a glacier running down the middle of the canyon. And there was very little frost steam rising from it. Still . . .