There were no compasses on Mars; there were, however, APS systems in his wristpad and back in the car. He could call up a detailed map on his wristpad and then locate himself and his car on it; then walk for a while and track his positions; then make his way directly toward the car. That seemed like a great deal of work— which brought it to him that his thinking, like his body, was being affected by the cold. It wasn’t that much work, after all.
So he crouched down in the lee of a boulder and tried the method. The theory behind it was obviously sound, but the instrumentation left something to be desired; the wristpad’s screen was only five centimeters across, so small that he couldn’t see the dots on it at all well. Finally he spotted them, walked awhile, and took another fix. But unfortunately his results indicated that he should be hiking at about a right angle to the direction he had been going.
This was unnerving to the point of paralysis. His body insisted that it had been going the right way; his mind (part of it, anyway) was pretty certain that it was better to trust the results on the wristpad, and assume that he had gotten off course somewhere. But it didn’t feel that way; the ground was still at a slope that supported the feeling in his body. The contradiction was so intense that he suffered a wave of nausea, the internal torque twisting him until it actually hurt to stand, as if every cell in his body was twisting to the side against the pressure of what the wristpad was telling him— the physiological effects of a purely cognitive dissonance, it was amazing. It almost made one believe in the existence of an internal magnet in the body, as in the pineal glands of migrating birds— but there was no magnetic field to speak of. Perhaps his skin was sensitive to solar radiation to the point of being able to pinpoint the sun’s location, even when the sky was a thick dark gray everywhere. It had to be something like that, because the feeling that he was properly oriented was so strong!
Eventually the nausea of the disorientation passed, and in the end he stood and took off in the direction suggested by the wristpad, feeling horrible about it, listing a little uphill just to try to make himself feel better. But one had to trust instruments over instincts, that was science. And so he plodded on, traversing the slope, shading somewhat uphill, clumsier than ever. His nearly insensible feet ran into rocks that he did not see, even though they were directly beneath him; he stumbled time after time. It was surprising how thoroughly snow could obscure the vision.
After a while he stopped, and tried again to locate the rover by APS; and his wristpad map suggested an entirely new direction, behind him and to the left.
It was possible he had walked past the car. Was it? He did not want to walk back into the wind. But now that was the way to the rover, apparently. So he ducked his head down into the biting cold and persevered. His skin was in an odd state, itching under the heating elements crisscrossing his suit, numb everywhere else. His feet were numb. It was hard to walk. There was no feeling in his face; clearly frostbite was in the offing. He needed shelter.
He had a new idea. He called up Aonia, on Pavonis, and got her almost instantly.
“Sax! Where are you?”
“That’s what I’m calling about!” he said. “I’m in a storm on Daedalia! And I can’t find my car! I was wondering if you would look at my APS and my rover’s! And see if you can tell me which direction I should go!”
He put the wristpad right against his ear. “Ka wow, Sax.” It sounded like Aonia was shouting too, bless her. Her voice was an odd addition to the scene. “Just a second, let me check! . . . Okay! There you are! And your car too! What are you doing so far south? I don’t think anyone can get to you very quickly! Especially if there’s a storm!”
“There is a storm,” Sax said. “That’s why I called.”
“Okay! You’re about three hundred and fifty meters to the west of your car.”
“Directly west?”
“— and a little south! But how will you orient yourself?”
Sax considered it. Mars’s lack of a magnetic field had never struck him as such a problem before, but there it was. He could assume the wind was directly out of the west, but that was just an assumption. “Can you check the nearest weather stations and tell me what direction the wind is coming from?” he said.
“Sure, but it won’t be much good for local variations! Here, just a second, I’m getting some help here from the others.”
A few long icy moments passed.
“The wind is coming from west northwest, Sax! So you need to walk with the wind at your back and a touch to your left!”
“I know. Be quiet now, until you see what course I’m making, and then correct it.”