“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 out of the way when she stared at it. The hot plates were heated by an electric charge 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! Greatidea!”
“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 the 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 Arakdy, 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 Arrowheadtethered, and drive back home.”