Sax, the people in the Quarter who had actually constructed the things. Someone in communications, probably – there were quite a few who must have known.
“What about Hiroko?” Arkady asked.
They couldn’t decide. They didn’t know enough of her views to be able to guess what she might think. Nadia was pretty sure she was in on it, but couldn’t explain why. “I suppose,” she said, thinking about it, “I suppose I feel like there is this group around Hiroko, the whole farm team and a fair number of others, who respect her and – follow her. Even Ann, in a way. Although Ann will hate this when she hears about it! Whew! Anyway, it just seems to me that she would know about anything secret going on. Especially something having to do with ecological systems. The bioengineering group works with her most of the time, after all, and for some of them she’s like a guru, they almost worship her. They probably got her advice when they were splicing this algae together!”
“Hmm …”
“So they probably got her agreement for the idea. Maybe I should even say her permission.”
Arkady nodded. “I see your point.”
On and on they talked, hashing over every point of it. The land they passed over, flat and immobile, looked different to Nadia now. It was seeded, fertilized; it was going to change, now, inevitably. They talked about the other parts of Sax’s terraforming plans, giant orbiting mirrors reflecting sunlight onto the dawn and dusk terminators, carbon distributed over the polar caps, areothermal heat, the ice asteroids. It was all really going to happen, it seemed. The debate had been bypassed; they were going to change the face of Mars.
The second evening after their momentous discovery, as they were cooking dinner in a crater’s lee anchorage, they got a call from Underhill, relayed off one of the comm satellites. “Hey you two!” John Boone said by way of greeting. “We’ve got a problem!”
“You’ve got a problem,” Nadia replied.
“Why, something wrong out there?”
“No no.”
“Well good, because really it’s you guys who have the problem, and I wouldn’t want you to have more than one! A dust storm has started down in the Claritas Fossae region, and it’s growing, and coming north at a good rate. We think it’ll reach you in a day or so.”
“Isn’t it early for dust storms?” Arkady asked.
“Well no, we’re at Ls = 240, which is pretty much the usual season for it. Southern spring. Anyway, there it is, and it’s coming your way.”
He sent a satellite photo of the storm, and they studied their TV screen closely. The region south of Tharsis was now obscured by an amorphous yellow cloud.
“We’d better take off for home right now,” Nadia said after studying the photo.
“At night?”
“We can run the props on batteries tonight, and recharge the batteries tomorrow morning. After that we may not have much sunlight, unless we can get above the dust.”
After some discussion with John, and then with Ann, they cast off. The wind was pushing them east-northeast, and on this heading they would pass just to the south of Olympus Mons. After that their hope was to get around the north flank of Tharsis, which would protect them from the dust storm for at least a while.
It seemed louder flying at night. The wind’s rush over the fabric of the bag was a fluctuating moan, the sound of their engines a pitiful little hum. They sat in the cockpit, lit only by dim green instrument lights, and talked in low voices as they moved over the black land below. They had about three thousand kilometers to go before reaching Underhill; that was about three hundred hours of flying time. If they went round the clock, it would be twelve days or so. But the storm, if it grew in the usual pattern, would reach them long before then. After that – it was hard to tell how it would go. Without sunlight the props would drain the batteries, and then – “Can we just float on the wind?” Nadia said. “Use the props for occasional directional nudges?”
“Maybe. But these things are designed with the props as part of the lift, you know.”
“Yeah.” She made coffee and brought mugs of it up to the cockpit. They sat and drank, and looked out at the black landscape, or the green sweep of the little radar screen. “We probably ought to drop everything we don’t need. Especially those damned windmills.”
“It’s all ballast, save it for when we need the lift.”
The hours of the night wore on. They traded shifts at the helm, and Nadia caught an uneasy hour’s sleep. When she returned to the cockpit, she saw that the black bulk of Tharsis had rolled over the horizon ahead of them: the two northernmost of the three prince volcanoes, Ascraeus Mons and Pavonis Mons, were visible as humps of occluded stars, out at the edge of the world. To their left Olympus Mons still bulked well above the horizon, and taken with the other two volcanoes, it looked as if they flew low in some truly gigantic canyon. The radar screen reproduced the view in miniature, in green lines on the screen’s gridwork.
Then, in the hour before dawn, it seemed as though another massive volcano were rising behind them. The whole southern horizon was lifting, low stars disappearing as they watched, Orion drowned in black. The storm was coming.
It caught them just at daybreak, choking off the red in the eastern sky, rolling over them, returning the world to rusty darkness. The wind picked up until it swept past the gondola windows in a muted roar, and then with a loud howling; dust flew by them with terrifying, surreal speed. Then the wind grew even more violent, and the gondola jerked up and down as the frame of the dirigible was twisted back and forth.
They were lucky north was the direction they wanted to go. At one point Arkady said, “The wind should hopefully wrap around the north shoulder of Tharsis.”
Nadia nodded silently. They hadn’t gotten the chance to recharge the batteries after the night’s flight, and without sunlight the motors wouldn’t run too much longer. “Hiroko told me sunlight on the ground during a storm is supposed to be about fifteen percent of normal,” she said. “Higher there should be more. So we’ll get some recharge, but it’ll be slow. Could be that over the course of the day we might get enough to use the props a bit tonight.” She flicked on a computer to do the calculations. Something in the expression on Arkady’s face – not fear, not even anxiety, but a curious little smile – made her aware of how much danger they were in. If they couldn’t use the props, they wouldn’t be able to direct their movement, and they might not even be able to stay aloft. They could descend, it was true, and try to anchor; but they had only a few weeks’ more food, and storms like these often persisted for two months, sometimes three.
“There’s Ascraeus Mons,” Arkady said, pointing at the radar screen. “Good image.” He laughed. “Best view of it we’re going to get this time around, I’m afraid. Too bad, I was really looking forward to seeing them! Remember Elysium?”
“Yeah yeah,” Nadia said, busy running simulations of the batteries’ efficiency. Daily sunlight was near its perihelion peak, which was why the storm had started in the first place; and the instruments said that about twenty percent of full daylight was penetrating to this level (it felt to her eye more like thirty or forty); therefore it might be possible to run the props half the time, which would help tremendously. Without them they were moving at around twelve kilometers per hour, and losing altitude as well, although that might just be the ground rising under them. With the props they might be able to hold a steady altitude, and influence their course by a degree or two.
“How thick is this dust, do you think?”
“How thick?”
“You know, grams per cubic meter. Try to get Ann or Hiroko on the radio and find out, will you?”
She went back to see what they had on board that could be used to power the props. Hydrazine, for the bomb bay vacuum pumps; the pump motors could be wired to the props, probably … She was kicking one of the damned windmills