planetary model built back in Germany by Friedrichshafen Noch Einmal, and shipped up in 2029, so that it had just recently arrived. It was called the Arrowhead, and it measured 120 meters across the wings, a hundred meters front to back, and forty meters tall. It had an internal ultralite frame, and turboprops at each wingtip and under the gondola; these were driven by small plastic engines whose batteries were powered by solar cells arrayed on the upper surface of the bag. The pencil-shaped gondola extended most of the length of the underside, but it was smaller inside than Nadia had expected, because much of it was temporarily filled with their cargo of windmills; at takeoff their clear space consisted of nothing more than the cockpit, two narrow beds, a tiny kitchen, an even smaller toilet, and the crawlspace necessary to move among these. It was pretty tight, but happily both sides of the gondola were walled with windows, and though somewhat blocked by windmills these still gave them a lot of light, and good visibility.
Takeoff was slow. Arkady released the lines extending from the three mooring masts with the flip of a cockpit toggle; the turboprops ran hard, but they were dealing with air that was only twelve millibars thick. The cockpit bounced up and down in slow motion, flexing with the internal frame: and every up bounce was a little higher off the ground. For someone used to rocket launches it was comical.
“Let’s 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 superlight materials gave them the lift to carry a cargo like their windmills, but with such a cargo aboard they were ludicrously sluggish.
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 ten kilometers per hour. 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