Green Mars(257)

“Oh my God.” She went to the nearest screen, her heart thudding in her chest. It was three A.M. “Is there a chance ice will choke the gap, and serve as a dam?”

Sax squinted. “I don’t think so. Depends on how big the gap is.”

“Can we set counterexplosions and close the gap?”

“I don’t think so. Look, here’s video sent from some Reds south of the break on the dike.” He pointed at a screen, which displayed an IR image with black to the left and blackish green to the right, and a forest-green spill across the middle. “That’s the blast zone there in the middle, warmer than the regolith. The explosion appears to have been set next to a pod of liquid water. Or else there was an explosion set to liquefy the ice behind the break. Anyway, that’s a lot of water coming through. And that will widen the break. No, we’ve got a problem.”

“Sax,” she exclaimed, and held on to his shoulder as she stared at the screen. “The people in Burroughs, what are they supposed to do? God damn it, what could Ann be thinking?”

“It might not have been Ann.”

“Ann or any of the Reds!”

“They were attacked. It could have been an accident. Or someone on the dike must have thought they were going to get forced away from the explosives. In which case it was a use-it-or-lose-it situation.” He shook his head. “Those are always bad.”

“Damn them.” Nadia shook her head hard, trying to clear it. “We have to do something!” She thought frantically. “Are the mesa tops high enough to stay above the flood?”

“For a while. But Burroughs is at about the lowest point in that little depression. That’s why it was sited there. Because the sides of the bowl gave it long horizons. No. The mesa tops will get covered too. I can’t be sure how long it will take, because I’m not sure of the flow rate. But let’s see, the volume to be filled is about . . .” He tapped away madly, but his eyes were blank, and suddenly Nadia saw that there was another part of his mind doing the calculation faster than the AI, a gestalt envisioning of the situation, staring at infinity, shaking his head back and forth like a blind man. “It could be pretty fast,” he whispered before he was done typing. “If the melt pod is big enough.”

“We have to assume it is.”

He nodded.

They sat there beside each other, staring at Sax’s AI.

Sax said hesitantly, “When I was working in Da Vinci, I tried to think out the possible scenarios. The shapes of things to come. You know? And I worried that something like this might happen. Broken cities. Tents, I thought it would be. Or fires.”

“Yes?” Nadia said, looking at him.

“I thought of an experiment— a plan.”

“Tell me,” Nadia said evenly.

But Sax was reading what looked like a weather update, which had just appeared over the figures scrolling on his screen. Nadia patiently waited him out, and when he looked up from his AI again, she said, “Well?”

“There’s a high-pressure cell, coming down Syrtis from Xanthe. It should be here today. Tomorrow. On Isidis Planitia the air pressure will be about three hundred and forty millibars, with roughly forty-five percent nitrogen, forty percent oxygen, and fifteen percent carbon diox—”

“Sax, I don’t care about the weather!”

“It’s breathable,” he said. He eyed her with that reptile expression of his, like a lizard or a dragon, or some cold posthuman creature, fit to inhabit the vacuum. “Almost breathable. If you filter the CO2. And we can do that. We manufactured face-masks in Da Vinci. They’re made from a zirconium alloy lattice. It’s simple. CO2 molecules are bigger than oxygen or nitrogen molecules, so we made a molecular sieve filter. It’s an active filter too, in that there’s a piezoelectric layer, and the charge generated when the material bends during inhalation and exhalation— powers an active transfer of oxygen through the filter.”

“What about dust?” Nadia said.

“It’s a set of filters, graded by size. First it stops dust, then fines, then CO2.” He looked up at Nadia. “I just thought people might— need to get out of a city. So we made half a million of them. Strap the masks on. The edges are sticky polymer, they stick to skin. Then breathe the open air. Very simple.”

“So we evacuate Burroughs.”

“I don’t see any alternative. We can’t get that many people out by train or air fast enough. But we can walk.”

“But walk to where?”

“To Libya Station.”

“Sax, it’s about seventy k from Burroughs to Libya Station, isn’t it?”