take a three-sixty and see Underhill before we go,” Arkady said when they were fifty meters high. He banked the ship and they made a slow wide turn, looking out Nadia’s window. Tracks, pits, mounds of regolith, all dark red against the dusty orange surface of the plain – it looked as if a dragon had reached down with a great taloned claw, and drawn blood time after time. Underhill sat at the center of the wounds, and by itself was a pretty sight, a square dark red setting for a shiny glass-and-silver jewel, with green just visible under the dome. Extending away from it were the roads east to Chernobyl and north to the spacepads. And over there were the long bulbs of the greenhouses, and there was the trailer park …
“The Alchemists’ Quarter still looks like something out of the Urals,” Arkady said. “We really have to do something about that.” He brought the dirigible out of its turn and headed east, moving with the wind. “Should I run us over Chernobyl and catch the updraft?”
“Why don’t we see what this thing can do unassisted?” Nadia said. She felt light, as if the hydrogen in the ballonets had filled her as well. The view was stupendous, the hazy horizon perhaps a hundred kilometers away, the contours of the land all clearly visible: the subtle bumps and hollows of Lunae, the more prominent hills and canyons of the channeled terrain to the east. “Oh, this is going to be wonderful!”
“Yes.”
It was remarkable, in fact, that they had not done anything like this before. But flying on Mars was no easy thing, because of the thin atmosphere. They were in the best solution: a dirigible as big and light as possible, filled with hydrogen, which in Martian air was not only not flammable, but also even lighter relative to its surroundings than it would have been on Earth. Hydrogen and the latest in super-light materials gave them the necessary lift to carry a cargo like their windmills, but with such a cargo aboard they were ludicrously sluggish, and everything happened in extreme slow motion.
And so they drifted along. All that day they crossed the rolling plain of Lunae Planum, pushed southeast by the wind. For an hour or two they could see Juventa Chasm on the southern horizon, a gash of a canyon that looked like a giant pit mine. Farther east, the land turned yellowish; there was less surface rubble, and the underlying bedrock was more rumpled. There were also many more craters, craters big and small, crisp-rimmed or nearly buried. This was Xanthe Terra, a high region that was topographically similar to the southern uplands, here sticking into the north between the low plains of Chryse and Isidis. They would be over Xanthe for some days, if the prevailing westerlies held true.
They were progressing at a leisurely 10 kph. Most of the time they flew at an altitude of about a hundred meters, which put the horizons about fifty kilometers away. They had time to look closely at anything they wanted to, although Xanthe was proving to be little more than a steady succession of craters.
Late that afternoon Nadia tilted the nose of the dirigible down and circled into the wind, dropping until they were within ten meters of the ground and then releasing their anchor. The ship rose, jerked on its line, and settled downwind of the anchor, tugging at it like a fat kite. Nadia and Arkady twisted down the length of the gondola, to what Arkady called the bomb bay. Nadia lifted a windmill onto the bay’s winch hook. The windmill was a little thing, a magnesium box with four vertical vanes on a rod projecting from its top. It weighed about five kilos. They closed the bay door on it, sucked out the air, and opened the bottom doors. Arkady operated the winch, looking through a low window to see what he was doing. The windmill dropped like a plumb, and bumped onto hardened sand, on the southern flank of a small unnamed crater. He released the winch hook, reeled it back into the bay and closed the bomb doors.
They returned to the cockpit, and looked down again to see if the windmill was working. There it stood, a small box on the outside slope of a crater, somewhat tilted, the four broad vertical blades spinning merrily. It looked like an anemometer from a kid’s meteorology kit. The heating element, an exposed metal coil that would radiate like a stove-top, was on one side of the base. In a good wind the element might get up to 200° Centigrade, which wasn’t bad, especially in that ambient temperature. Still … “It’s going to take a lot of those to make any difference,” Nadia remarked.
“Sure, but every little bit helps, and in a way it’s free heat. Not only the wind powering the heaters, but the sun powering the factories making the windmills. I think they’re a good idea.”
They stopped once more that afternoon to set out another one, then anchored for the night in the lee of a crisp young crater. They microwaved a meal in the tiny kitchen, and then retired to their narrow bunks. It felt odd to rock on the wind, like a boat at its mooring: tug and float, tug and float. But it was very relaxing when you got used to it, and soon Nadia was asleep.
The next morning they woke before dawn, cast off, and motored up into the sunlight. From a hundred meters height they could watch the shadowed landscape below turn to bronze as the terminator rolled by and clear daylight followed, illuminating a fantastic jumble of bright rocks and long shadows. The morning wind pushed right to left across their bow, so they were pushed northeast toward Chryse, humming along with the props on full power. Then the land fell away below them, and they were over the first of the outflow channels they would pass, a sinuous unnamed valley west of Shalbatana Vallis. This little arroyo’s S shape was unmistakably water-cut. Later that day they lofted out over the deeper and much wider canyon of Shalbatana, and the signs were even more obvious: tear-shaped islands, curving channels, alluvial plains, scablands; there were signs everywhere of a massive flood, a flood that had created a canyon so huge that the Arrowhead suddenly looked like a butterfly.
The outflow canyons and the high land between them reminded Nadia of the landscape of American cowboy movies, with washes and mesas and isolated ship rocks, as in Monument Valley – except here it lasted for four days, as they passed in succession over the unnamed channel, Shalbatana, Simud, Tiu, and then Ares. And all of them had been caused by giant floods, which had burst onto the surface and flowed for months, at rates ten thousand times that of the Mississippi. Nadia and Arkady talked about that as they looked down into the canyons under them, but it was very hard to imagine floods so huge. Now the big empty canyons funnelled nothing but wind. They did that quite well, however, so Arkady and Nadia descended into them a number of times per day, to drop more windmills.
Then east of Ares Vallis they floated back over the densely cratered terrain of Xanthe. Again the land was everywhere marred by craters: big craters, little craters, old craters, new craters, craters with rims marred by newer craters, craters with floors punctured by three or five smaller craters; craters as fresh as if they had struck yesterday; craters that just barely showed, at dawn and dusk, as buried arcs in the old plateau. They passed over Schiaparelli, a giant old crater a hundred kilometers across; when they floated over its central uplift knob, its crater walls formed their horizon, a perfect ring of hills around the edge of the world.
After that winds blew from the south for several days. They caught a glimpse of Cassini, another great old crater, and passed over hundreds of smaller ones. They dropped several windmills per day, but the flight was giving them a stronger sense of the size of the planet, and the project began to seem like a joke, as if they flew over Antarctica and tried to melt the ice by setting down a number of camping stoves. “You’d have to drop millions to make any difference,” Nadia said as they climbed up from another drop.
“True,” Arkady said. “But Sax would like to drop millions. He’s got an automated assembly line that will just keep churning them out, it’s only distribution that is a problem. And besides, it’s just one part of the campaign he has in mind.” He gestured back toward the last arc of Cassini, inscribing the whole northwest. “Sax would like to bang out a few more holes like that one. Capture some icy moonlets from Saturn, or from the asteroid belt if he can find any, and push them back and smash them into Mars. Make hot craters, melt the permafrost – they’d be like oases.”
“Dry oases, wouldn’t they be? You’d lose most of the ice on entry, and have the rest disappear on contact.”
“Sure, but we can use more water vapor in the air.”
“But it wouldn’t just vaporize, it would break into its constituent atoms.”
“Some