from the occasional staticky voices the radio found in the jamming. On the very spine of the Geneva Spur, as they were crossing the absurdly thin concrete thread of the Transcanyon Highway, they were far enough out from the south wall to get some transmissions, something about it not becoming a global dust storm after all. And indeed the days were sometimes only hazy, rather than clotted with the dust. Sax claimed this as proof of the relative success of the dust-fixing strategies pursued since the Great Storm. No one responded to this. The haze that was in the air, Frank observed, seemed actually to help clarify weak radio signals. That was stochastic resonance, Sax said. The phenomenon was counterintuitive, and Frank questioned Sax closely for an explanation of it. When he understood, the room rang with his mirthless bray. “Maybe all the emigration was stochastic resonance, enhancing the weak signal of the revolution.”
“I don’t think it helps to make analogies between the physical and social worlds,” Sax said primly.
“Shut up, Sax. Go back to your virtual reality.”
Frank was still angry; bitterness sublimed from him like the frost steam off the flood. He snapped questions at Michel about the hidden colony, his curiosity bursting out two or three times a day. Ann was happy to think she would not be Hiroko when Frank first met her. Michel answered these accusing questions calmly, ignoring the sarcasm and the furious gleam in Frank’s eye. Maya’s attempts to cool Frank only increased his rage, but she kept at it. Ann was impressed at how persistent she was, how insensitive to Frank’s brusque rejections. It was a side of Maya that Ann had never seen before; Maya was usually the most volatile person around. But not now, not when the pressure was really on.
Eventually they rounded the Geneva Spur, and got back on the bench under the southern escarpment. The way east was often interrupted by landslides, but they always had room to veer left around them. Progress was good.
But then they came to the eastern end of Melas. Here the greatest chasm of them all narrowed, and dropped several hundred meters down into the two parallel canyons of Coprates, which were separated by a long narrow plateau. South Coprates dead-ended in a cliffy headwall some 250 kilometers away; North Coprates connected with the lower canyons farther east, and therefore was the one they wanted to take. North Coprates was the longest single segment of the Marineris system; Michel called it La Manche, and like the English Channel it narrowed as it progressed eastward, until at around 60 ° longitude it narrowed and reared into a gigantic gorge— sheer cliffs four kilometers high, facing each other across a gap only twenty-five kilometers across. Michel called this gorge the Dover Gate; apparently the cliff walls in this gap were whitish, or had been.
So they made their way down North Coprates, and the cliffs closed in on them more every day. The flood filled almost the whole width of the canyon floor, and its flow was so rapid that the ice on its surface had broken into small bergs, which flew off the lips of standing waves and crashed back into the cascade: a furious white- water rapid with the flow of a hundred Amazons, topped by icebergs. The canyon floor was being ripped away, torn free of its bed and rushing down in red jolts of water like massive pulses of rusty blood, as if the planet were bleeding to death. The noise was incredible, a roar so continuous and pervasive that it dulled thought, and made talk almost impossible; they had to shout everything at the top of their lungs, which quickly reduced them to communicating only the basic necessities.
But then there was a very basic necessity to shout about, for when they came to the Dover Gate they found that the canyon floor was almost completely covered by the flood. Their bench below the southern wall of the gorge was no more than two kilometers wide, and diminishing every minute. It seemed possible the whole bench might be torn away in a flash. Maya cried that it was too dangerous to go on, and argued for a retreat. If they circled around and drove up to the dead end of South Coprates, she shouted, and managed to climb to the plateau above, then they could drive past the pits of Coprates, and proceed onward to Aureum.
Michel shouted his insistence that they press forward, and get through the Gate on the bench. “If we hurry we can make it! We must try!” And when Maya continued to protest, he added forcefully, “The head of South Coprates is steep! The car would never get up it, it’s a cliff like these! And we don’t have the supplies to add so many extra days to our trip! We can’t go back!”
The insane roar of the flood was his only answer. They sat in the car, in their separate thoughts, separated by the roar as if by many kilometers of space. Ann found herself wishing the bench would slide from under them, or a piece of the south wall fall onto them, and put an end to their indecision, and to the awful, maddening noise.
They drove on. Frank and Maya and Simon and Nadia stood behind Michel and Kasei, watching them drive. Sax sat at his screen, stretching like a cat, staring myopically at the little picture of the deluge. The surface calmed for a moment, and froze over, and the explosive noise reduced to a violent low rumble. “It’s like the Grand Canyon on a kind of super-Himalayan scale,” Sax said, apparently to himself, although only Ann would be able to hear him. “The Kala Gandaki Gorge is about three kilometers deep, isn’t it? And Dhaulagiri and Annapurna only forty or fifty kilometers apart, I think. Fill that with a flood like. .” He failed to recall any comparable flood. “I wonder what all that water was doing so high on the Tharsis Bulge.”
Cracks like gunshots announced another surge. The white surface of the flood blew apart and tumbled downstream. White noise suddenly enveloped them, battening everything they said or thought, as if the universe were vibrating. A bass tuning fork. .
“Outgassing,” Ann said. “Outgassing.” Her mouth was stiff, she could feel in her face how long it had been since she had last spoken. “Tharsis rests on an upwelling of magma. Rock alone couldn’t sustain the weight; the bulge would have subsided if it weren’t being supported by an upwelling current in the mantle.”
“I thought there was no mantle.” She could just hear him through the noise.
“No no.” She didn’t care if he could hear her or not. “It’s just slowed down. But currents are still there. And since the last great floods, they have refilled the high aquifers on Tharsis. And kept aquifers like Compton warm enough to stay liquid. Eventually the hydrostatic pressures were extreme. But with less vulcanism, and fewer big meteor strikes, nothing set it off. It might have been full for a billion years.”
“Do you think Phobos broke it open?”
“Maybe. More likely a reactor meltdown.”
“Did you know Compton was this big?” Sax asked.
“Yes.”
“I never heard of it.”
“No.”
Ann stared at him. Had he heard her say that?
He had. Concealing data— he was shocked, she could tell. He couldn’t imagine any reason good enough to conceal data. Perhaps this was the root of their inability to understand each other. Value systems based on entirely different assumptions. Completely different kinds of science.
He cleared his throat. “Did you know it was liquid?”
“I thought so. But now we know.”
Sax twitched, and called up on his screen the image from the left side camera. Black fizzing water, gray debris, shattered ice, boulders like great tumbling dice; standing waves freezing in place, collapsing and sweeping away in clouds of frost steam. . the noise had risen back to its crackling jet howl.
“I wouldn’t have done it this way!” Sax exclaimed.
Ann stared at him. He steadfastly regarded the TV.
“I know,” she said. And then she was tired of talk again, tired of its uselessness. It had never been any more than it was now: whispers against the great roar of the world, half-heard and less understood.
They drove as quickly as they could through the Dover Gate, following the Calais Ramp as Michel called their bench. Progress was nerve-rackingly slow, it was a bitter struggle to get the rover over the rockfall covering this narrow terrace; boulders were scattered everywhere, and the flood ate away at the land to their left, narrowing the bench at a perceptible rate. Landslides from the cliff walls fell ahead and behind them, and more than once individual rocks crashed into the car’s roof, making them all jump. It was perfectly possible that a bigger rock would hit them and smash them like bugs, without a single bit of warning. That possibility subdued them all, which was fine by Ann. Even Simon left her alone, throwing himself into the navigational effort and going out on scouting trips with Nadia or Frank or Kasei, happy, she thought, to have some excuse to get away from her. And why not?
They bumped along at a couple kilometers per hour. They traveled through a night and then the following
