He turned to the Russian, who was standing between him and the rover, looking down into the canyon. The rover’s bright aluminum finish was coated with reddish dust now, especially around the wheels and fenders. It made the vehicle look as if it were rusting.
Fighting down a tiny irrational fear that nagged at the back of his mind, Jamie called, "Mikhail, I’ve got to climb down to the bottom. I’ll need your help."
The Russian, in his red hard suit, started walking toward Jamie. "That is an unnecessary risk."
Jamie made himself laugh. "I’ve done a lot of rock climbing. And in full gravity, too."
"It is an unnecessary risk," Vosnesensky repeated.
"Then why did the mission planners allow us to stow climbing gear in the rover? Come on, Mikhail, with the winch and all it won’t be much of a risk at all. If you think I’m in danger you can haul me up whether I like it or not."
"The sun is setting. It will be too cold to work. Tomorrow you can have the whole day."
"I’m okay in the suit. We’ve got three-four hours before sunset," Jamie said. "Besides, the sun’s hitting this side of the canyon now. Tomorrow morning this side’ll be in shadow."
It was impossible to see the Russian’s face behind the gold-tinted visor of his helmet. He was silent for a long time, obviously thinking, weighing the options. Finally he said, "Very well. But when I say to come up, you do not argue."
"Deal," said Jamie.
Jamie spent the next hour inching slowly down the sheer rock face of the canyon wall, stopping every ten meters or so to chip out samples. He wore a climber’s harness over his hard suit, attached to the electrical winch at the canyon rim by a thin cable of composites stronger than steel. Jamie himself controlled the winch with a set of buttons built into the harness, although Vosnesensky could override him by using the controls on the winch itself or even hauling him up manually, if necessary.
The rock’s not stratified, Jamie saw. Seems to be all the same, all the way down to the bottom. That puzzled him. One thick slab of undifferentiated stone? How can that be? He remembered a novel he had read years ago, a scene where an infantry division had been assembled on a parade ground that was described as solid iron one mile thick. Had that scene been set on Mars? Jamie could not remember.
This is different from the area around the dome. There’s never been an ocean here to lay down silt deposits and have them turn into rock layers over the years. I’m looking at the actual mantle of the planet, the original material that made up the planet from its very beginning. One enormous slab of rock that must go down not just one lousy mile, it must be a hundred miles deep! Or even more!
Jamie dangled in midair, twisting slightly in the harness, staring at the reddish gray wall before his eyes. This stuff has been here since the planet was born, since it cooled off and solidified. It could be more than four billion years old! He was panting as if he had run a mile, as if he had just found the most precious diamond in the universe.
There was nothing like this on Earth. Mantle rock was always buried beneath miles of crust. Even the ocean beds were covered with sediments. You never saw exposed mantle rock on Earth. But Mars is different, Jamie said to himself. The old assumptions don’t apply here.
It’s not differentiated, he realized. That’s why there’s so much iron in the sand on the surface. The iron never sank into the core the way it did on Earth. It’s spread all over the surface. Why? How?
Up above, Vosnesensky took an automated sensor beacon from the rover’s cargo bin and busied himself setting it up. The anemometer immediately began turning, fast enough to surprise him. The air was so thin that even a stiff breeze was negligible. Toshima will be happy to have another station reporting to him, Vosnesensky said to himself as he turned on the isotope-powered telemetry radio.
Then he walked back to the winch. Planting his short legs as firmly as the machine’s on the dusty red ground, he took hours’ worth of video shots of the entire area.
Jamie took pictures too, with the still camera he carried in the equipment belt around his waist.
As he neared the bottom Jamie searched for signs of the actual fault line that had created the canyon. In vain. Eons of dust laid down by the winds that yearly billowed up into planetwide sandstorms had covered the canyon floor. Jamie smiled to himself, hanging in the climber’s harness. Give Mars another billion years or two and the canyons will be all filled in.
He did not like to look up while he dangled in the harness. The rock wall loomed above him, much too high and steep to climb. The other walls were kilometers away, but the deeper down Jamie went the closer they seemed to squeeze in on him. It made him feel trapped, frightened in a deep unreasoning part of his brain. So Jamie busied himself chipping away at the rock as he descended and scanning the floor below for any evidence of the fundamental crack in the ground that had started this canyon. He never found it.
What did you expect? he asked himself. Something as obvious as the San Andreas Fault?
"Time to come up," Vosnesensky called. "Now."
Despite himself Jamie leaned back in the harness and looked up. For a dizzying moment he felt as if the rock wall were tipping over to fall in on him.
But he heard himself complain, "I haven’t reached the bottom yet!"
"It is getting dark."
Swaying in the harness, Jamie realized that the shadows from the opposite canyon wall were almost upon him. He shuddered. Mikhail’s right; I don’t want to be down here in the dark.
"Okay, coming up," he said into his helmet microphone. He felt the harness tighten about him as the cable began pulling him. He held onto the cable with both gloved hands and tried to gain some purchase on the rock face with his boots as he rose. The winch did all the real work.
At last he reached the top. The sun was almost on the horizon. Even inside the heated suit Jamie shivered. The sky to the east was already dark.
Vosnesensky helped him remove the harness and equipment belt; then they started back toward the rover.
Jamie halted his companion with an outstretched hand.
"Wait a minute, Mikhail. We’ve been on Mars almost a week and we haven’t really watched a sunset."
The Russian made a sound halfway between a grunt and a snort, but he stopped. The two of them stood there on the broad Martian plain, their hands filled with the climbing equipment, and watched the tiny pale sun touch the flat horizon. The sunset was not spectacular. No flaming colors of breathtaking beauty. The air was too thin, too dry, too clean. And yet…
The pink sky deepened into red, then violet, uniformly, evenly, the way the dome of a planetarium softly dims when its lights are turned down toward darkness.
"Look!" Jamie pointed as the sun dipped out of sight. A single lonely wisp of a cloud hung above the horizon, glowing like a silver ghost briefly. Then the sun disappeared and the cloud faded into the all-encompassing darkness.
"This is more beautiful than I could have imagined." Vosnesensky’s voice was softer, gentler than Jamie had heard before.
"It sure is. I wonder…"
Jamie’s words died in his throat. His heart began to pound. The sky was shimmering, glowing faintly as a spirit hovering above them, flickering colors so pale and delicate that for a breathless moment Jamie could not believe his eyes.
"Mikhail…"
"I see it. Aurora."
"Like the northern lights." Jamie’s voice was hollow with awe, trembling. The lights pulsed and billowed across the sky, exquisitely ethereal pastels of pink, green, blue, and white. He could see stars through them, faintly.