generated by the spinning of the windmills. So if she could run that charge into the prop batteries, the windmills could be attached to the outside of the gondola, and this wind would spin them like tops, and the resulting electricity could help power the props. As she rooted through the equipment locker looking for wire and transformers and tools she told Arkady the idea, and he laughed his madman laugh. “Good idea, Nadia! Great idea!”
“If it works.” She rummaged through the tool kit, sadly smaller than her usual supply. The light in the gondola was eerie, a dim yellow glow flickering with every gust. The view out the side windows shifted from pockets of complete clarity, with thick yellow clouds like thunderheads flying past them, to complete obscurity, all the window surfaces streaming with dust that flashed by at well over three hundred kilometers per hour. Even at twelve millibars the blast of the wind was tossing the dirigible about; up in the cockpit Arkady was cursing the autopilot’s insufficiency. “Reprogram it,” Nadia called forward, and then remembered him and all his sadistic simulations on the Ares, and laughed out loud: “Problem run! Problem run!” She laughed again at his shouted curses, and went back to work. At least the wind would push them along faster. Arkady yelled back information from Ann: the dust was extremely fine, average particle size about 2.5 microns; total column mass about 10-3 grams per cm-2, pretty evenly distributed from top to bottom of the column. That wasn’t so bad; drop it on the ground and it would be a really thin layer, which was consistent with what they had seen on the oldest freight drops at Underhill.
When she had rewired a number of the windmills she banged down the passageway to the cockpit. “Ann says the winds will be slowest close to the ground,” Arkady said.
“Good. We need to land to get those windmills outside.”
So that afternoon they descended blind, and let the anchor drag until it hooked and held. The wind here was slower, but even so Nadia’s descent in the sling was harrowing; down and down into rushing clouds of yellow dust, swinging back and forth … and there it was right under her boots, the ground! She hit and dragged to a halt. Once out of the sling she found herself leaning into the wind; thin as it was it still struck like blows, and her old feeling of hollowness was extreme. Visibility billowed back and forth in waves, and the dust flew past so fast it was disorienting; on Earth a wind that fast would simply pick you up and throw you, like a broomstraw in a tornado.
But here you could hold your ground, if only just. Arkady had been slowly winching the dirigible down on its anchor line, and now it bulked over her like a green roof. It was weirdly dark underneath it. She unreeled the wires out to the wingtip turboprops, taped them to the dirigible and crimped them to the contacts inside, working fast to try to reduce their exposure to dust, and to get out from under the Arrowhead; it was bouncing on the wind. With difficulty she drilled holes in the bottom of the gondola fuselage, and attached ten windmills with screws. As she was taping the wiring from these to the plastic fuselage, the whole dirigible dropped so fast that she had to collapse onto her face, her whole body spreadeagled on the cold ground, the drill a hard lump under her stomach. “Shit!” she shouted. “What’s wrong?” Arkady cried over the intercom. “Nothing,” she said, jumping up and taping faster than ever. “Fucking thing – it’s like working on a trampoline!” Then as she was finishing the wind picked up strength yet again, and she had to crawl back down to the bomb bay, her breath rasping in and out of her.
“The damn thing almost crushed me!” she shouted forward to Arkady when she had her helmet off. While he worked to unhook the anchor she staggered around the interior of the gondola, picking up things that they wouldn’t need and taking them into the bomb bay: a lamp, one of the mattresses, most of the cooking utensils and dinnerware, some books, all the rock samples. In they went, and she jettisoned them happily. If some traveler ever came upon the resulting pile of stuff, she thought, they would really wonder what the hell had happened.
They had to run both props full out to get the anchor unhooked, and when they succeeded they were off and flying like a leaf in November. They kept the props on full, to gain altitude as fast as possible; there were some small volcanoes between Olympus and Tharsis, and Arkady wanted to pass several hundred meters over them. The radar screen showed Ascraeus Mons falling steadily behind. When they were well north of it they could turn east, and try to chart a course around the northern flank of Tharsis, and then down to Underhill.
But as the long hours passed they found that the wind was rushing down the north slope of Tharsis, across their bow; so that even when running full power toward the southeast, they were still only moving northeast at best. In their attempts to fly across the wind the poor Arrowhead was bouncing like a hang glider, yanking them up and down, up and down, up and down, as if the gondola were indeed attached to the underside of a trampoline. But despite all that, they still weren’t going in the direction they wanted to go.
Darkness fell again. They were carried farther northeast. On this heading, they were going to miss Underhill by several hundred kilometers. After that, nothing; no settlements at all, no refuge. They would be blown over Acidalia, up onto Vastis Borealis, up to the empty petrified sea of black dunes. And they did not have enough food and water to circumnavigate the planet again and give it another try.
Feeling dust in her mouth and eyes, Nadia went back to the kitchen and heated them a meal. Already she was exhausted, and, she realized as the smell of food filled the air, extremely hungry. Thirsty, too; and the water recycler ran on hydrazine.
Thinking about water, an image came to her mind, from the trip to the north pole: that broken permafrost gallery, with its white spill of water ice. Now how was that relevant?
She worked her way back up to the cockpit, holding onto a wall with every step. She ate a dusty meal with Arkady, trying to figure it out. Arkady watched their radar screen, saying nothing; but he was looking concerned.
Ah. “Look,” she said, “if we could pick up the signals from the transponders on our road to Chasma Borealis, we could come down and land by it. Then one of the robot rovers could be sent up to get us. The storm won’t matter to the robot rovers, they don’t go by sight anyway. We could leave the Arrowhead tethered, and drive back home.”
Arkady looked at her, finished swallowing. “Good idea,” he said.
But only if they could actually pick up the road’s transponder signals. Arkady flicked on the radio and called Underhill. The connection crackled in a storm of static almost as dense as the dust, but they could still make themselves understood. All through that night they conferred with the crowd back home, discussing frequencies, bandwidths, the power of the dust to mask the transponders’ fairly weak signals, and so on. Because the transponders were designed only to signal rovers that were nearby and on the ground, it was going to be a problem hearing them. Underhill might be able to pinpoint their location well enough to tell them when to descend, and their own radar map would give them a general fix on the road’s location as well; but neither of these methods would be very exact, and it would be almost impossible to find the road in the storm if they didn’t land right on it. Ten kilometers either way and it would be over the horizon, and they would be out of luck. It would be a lot more certain if they could just latch onto one of the transponder signals, and follow it down.
In any case, Underhill dispatched a robot rover on the road north. It would arrive in the area of the road they were expected to cross in about five days; at their current speed, now nearly thirty kilometers per hour, they would cross the road themselves in about four days.
When the arrangements were finished, they traded watches through the rest of the night. Nadia slept uneasily on her off watches, and spent much of the time lying on the bed feeling the wind bounce her. The windows were as dark as if curtains had been drawn. The roar of the wind was like a gas stove, and then occasionally like banshees; once she dreamed they were inside a great furnace full of flame demons, and woke sweating, and went forward to relieve Arkady. The whole gondola smelled of sweat and dust, and burnt hydrazine. Despite all the gaskets’ micron seals, there was a visible whitish film on all the surfaces inside the gondola. She wiped her fingers across a pale blue plastic bulkhead, and stared at her fingers’ mark. Incredible.
They bounded along through the gloom