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….