the western wall, aiming toward a transponder that had been included in a drop of ice-mining equipment. The sand dunes mid-chasm were low and regular, and the rovers rolled over the corrugated land, up and down, up and down. Then as they crested a sand wave they spotted the drop, no more than two kilometers from the foot of the northwest ice wall: bulky lime green containers on skeletal landing modules, a strange sight in this world of whites and tans and pinks. “What an eyesore!” Ann exclaimed, but Phyllis and George were cheering.
During the long afternoon, the shadowed western iceside took on a variety of pale colors: the purest water ice was clear and bluish, but most of the hillside was a translucent ivory, copiously tinted by pink and yellow dust. Irregular patches of CO2 ice were a bright pure white; the contrast between dry ice and water ice was vivid, and made it impossible to read the actual contours of the hillside. And foreshortening made it hard to tell how tall the hill really was; it seemed to go up forever, and was probably somewhere between three and five hundred meters above the floor of Borealis.
“This is a lot of water,” Nadia exclaimed.
“And there’s more underground,” Phyllis said. “Our borings show that the cap actually extends many degrees of latitude farther south than we see, buried under the layered terrain.”
“So we have more water than we’ll ever need!”
Ann pursed her mouth unhappily.
The drop of the mining equipment had determined the site of the ice mining camp: the west wall of Chasma Borealis, at longitude 41°, latitude 83° N. Deimos had just recently followed Phobos under the horizon; they wouldn’t see it again until they returned south of 82° N. The summer nights consisted of an hour’s purple twilight; the rest of the time the sun wheeled around, never more than twenty degrees above the horizon. The six of them spent long hours outside, moving the ice miner to the wall and then setting it up. The main component was a robotic tunnel borer, about the size of one of their rovers. The borer cut into the ice, and passed back cylindrical drums 1.5 meters in diameter. When they turned the borer on it made a loud, low buzz, which was louder still if they put their helmets to the ice, or even touched it with their hands. After a while white ice drums thumped into a hopper, and then a small robot forklift carried them to a distillery, which would melt the ice and separate out its considerable load of dust, then refreeze the water into one-meter cubes more suitable for packing in the holds of the rovers. Robot freight rovers would then be perfectly capable of driving to the site, loading up and returning to base on their own; and base would then have a regular water supply, larger than they could ever use. Around four or five trillion cubic kilometers in the visible polar cap, Edvard calculated, though there were a lot of guesses in the calculation.
They spent several days testing the miner and deploying an array of solar panels to power it. In the long evenings after dinner Ann would climb the ice wall, ostensibly to take more borings, although Nadia knew she just wanted away from Phyllis and Edvard and George. And naturally she wanted to climb all the way to the top, to get on the polar cap and look around, and take borings of the most recent layers of ice; and so one day when the miner had passed all the test routines, she and Nadia and Simon got up at dawn – just after two a.m. – and went out into the supercold morning air and climbed, their shadows like big spiders climbing before them. The slope of the ice was about 30°, steepening and then letting off time after time as they ascended the rough benches in the hill’s layered side.
It was seven a.m. when the slope laid back and they walked onto the surface of the polar cap. To the north was a plain of ice that extended as far as they could see, to a high horizon some thirty kilometers away. Looking back to the south they could see a great distance over the geometric swirls of the layered terrain; it was the longest view Nadia had ever had on Mars.
The ice of the plateau was layered much like the laminated sand below them, with wide bands of dirty pink contouring across cleaner stuff. The other wall of Chasma Borealis lay off to the east, looking almost vertical from their point of view, long, tall, massive: “So much water!” Nadia said again. “It’s more than we’ll ever need.”
“That depends,” Ann said absently, screwing the frame of the little borer into the ice. Her darkened faceplate turned up at Nadia: “If the terraformers have their way, this will all go like dew on a hot morning. Into the air to make pretty clouds.”
“Would that be so bad?” Nadia asked.
Ann stared at her. Through the tinted faceplate her eyes looked like ballbearings.
That night at dinner she said, “We really ought to make a run up to the pole.”
Phyllis shook her head. “We don’t have the food or air.”
“Call for a drop.”
Edvard shook his head. “The polar cap is cut by valleys almost as deep as Borealis!”
“Not so,” Ann said. “You could drive straight to it. The swirl valleys look dramatic from space, but that’s because of the difference in albedo between the water and the CO2. The actual slopes are never more than 6° off the horizontal. It’s just more layered terrain, really.”
George said, “But what about getting onto the cap in the first place?”
“We drive around to one of the tongues of ice that drop to the sand. They’re like ramps up to the central massif, and once there, we drive right to the pole!”
“There’s no reason to go,” Phyllis said. “It’ll just be more of what we see here. And it means more exposure to radiation.”
“And,” George added, “we could use what food and air we do have to check out some of the sites we passed on the way up here.”
So that was their point. Ann scowled. “I’m the head of the geological survey,” she said sharply. Which may have been true, but she was a horrible politician, especially compared to Phyllis, who had any number of friends in Houston and Washington.
“But there’s no geological reason to go to the pole,” Phyllis said now with a smile. “It’ll be the same ice as here. You just want to go.”
“Well?” Ann said. “Say I do! There are still scientific questions to be answered up there. Is the ice the same composition, how much dust – everywhere we go up here we collect valuable data.”
“But we’re up here to get water. We’re not up here to fool around.”
“It’s not fooling around!” Ann snapped. “We obtain water to allow us to explore, we don’t explore just to obtain water! You’ve got it backwards! I can’t believe how many people in this colony do that!”
Nadia said, “Let’s see what they say at base. They might want us to help with something there, or they might not be able to send a drop, you never know.”
Ann groaned. “We’ll end up asking permission from the UN, I swear.”
She was right. Frank and Maya didn’t like the idea, John was interested but noncommittal. Arkady supported it when he heard of it, and declared he would send a supply drop from Phobos if necessary, which given its orbit was impractical at best. But at that point Maya called mission control in Houston and Baikonur, and the argument rippled outward. Hastings opposed the plan; but Baikonur, and a lot of the scientific community, liked it.
Finally Ann got on the phone, her voice very curt and arrogant, though she looked scared: “I’m the geological head here, and I say it needs to be done. There won’t be any better opportunity to get onsite data on the original condition of the polar cap. It’s a delicate system, and any change in the atmosphere is going to impact it heavily. And you’ve got plans to do that, right? Sax, are you still working on those windmill heaters?”
Sax had not been part of the discussion and he had to be called to the phone. “Sure,” he said when the question was repeated. He and Hiroko had come up with the idea of manufacturing small windmills, to be dropped from dirigibles all over the planet. The constant westerlies would spin the windmills, and the spin would be converted to