Ordinarily, that would not be a problem. However, in its tumble downhill, the rover had snapped off the antennas needed by both the over-the-horizon radios and the satellite navigation system. Without these, they could become fatally lost on the featureless plain.
McGee fiddled with his jury-rigged antenna, trying to make it work. From inside the rover came Rebecca's voice. "No luck. Nothing but static. Kevin, we've wasted precious hours trying to fix this thing. I've got to get these samples back to the lab for immediate analysis. Let's just bag the repair job and get going."
McGee groaned. Rebecca was so obsessed with her potential discovery that she was oblivious to their plight.
"Rebecca, I don't think you get it. Without the nav system, the odds of our finding our way back to the Hab are low, even in daylight. At night, it's going to be nearly impossible."
Rebecca exited the rover and joined McGee outside. She examined the repair job. It seemed like it should work. In all probability, a good mechanic could get the system functioning within minutes. Unfortunately, the nearest such person was over a hundred miles away, and without their radio, they had no way to call for help. Mars' weak magnetic field made compasses useless; they needed the satellite nav system to guide them home.
Rebecca stared bleakly at the wiring, then at the crumbly slope they had just descended. The avalanche had exposed bare and broken rock everywhere—Mars rocks free of deposited dust. They looked quite unusual. For a moment, the thought crossed her mind that she should photograph the slope for Luke. The fresh, raw image might have some geological value.
No, rocks could wait. She had to get back with her samples.
Rebecca looked to the west. It was a very clear evening, and the Sun was just going down. With no dust in the thin air, there was virtually no sunset, and no twilight. Instead, deep night fell like a thick curtain.
Suddenly McGee cried out. She turned, amazed at what she saw. The entire slope was glowing: soft pinks, greens, blues, violets, like an enormous mountain of iridescent jewels. It was eerie and beautiful—one of the most magnificent sights she had ever seen. For several seconds she couldn't breathe.
"Can you explain it, Rebecca?"
McGee's question broke her reverie, and her analytical mind switched into gear. "Phosphorescence, I think. The ridge is covered with calcite and fluorite, and other phosphorescent minerals. The avalanche exposed a lot of virgin surface, which is glowing due to excitation from solar UV. I don't think it will last long."
Sure enough, within less than a minute the glow faded, leaving the two explorers in a darkness lit only by a magnificent canopy of stars.
With the fall of night, the temperature, which had been descending all afternoon, started to drop fast. The two spent a few moments admiring the constellations, then returned to the rover cabin for warmth. But McGee now had food for thought.
Inside the rover, he pulled off his helmet and waited for the doctor to remove hers. "Rebecca, I think I have an idea."
"What is it?" She asked with a trace of hope.
"The stars. We can navigate home by using the stars to provide direction, and the rover's odometer for dead reckoning against our maps."
Rebecca's expression brightened, then exploded into sunshine. "That's great! That means we can make it back tonight! Kevin, you're a wonder." She paused. "But we need to know the location of Mars' north celestial pole. It's not Polaris, I'm sure of that. Let's see: Mars' vernal equinox points toward Gemini, and tilts at twenty-four degrees. But to calculate the location of the pole we need to know—
McGee cut short her calculations. "Rebecca, I know the answer."
"You do?"
"Yes. Mars' north celestial pole is located about halfway between Deneb and Alpha Cephei."
"How do you get that?"
"It says so right here."
Rebecca looked over at the text displayed on McGee's electropad. It had been many years since she'd first read it, but she recognized the passage instantly, from The Case for Mars, published in 1996.
Rebecca grinned. "Leave it to you, Kevin, to keep classics in your pad memory." She pointed out the window, "There's Deneb, Cygnus the Swan's tail, and there's Alpha Cephei. We'll lose them when we cross the equator, but if they mark north," she turned to look in the opposite direction, "that constellation will give us south."
Rebecca turned to McGee and smiled. "It's Vela, the sails of the Argo." She switched her penlite to illuminate her map. "So, to keep it simple, all you need to do is travel forty-four miles at bearing 090 and then head down at bearing 150 for another 115 miles—and we should hit it on the nose. It's all flat and level. At top speed, we can make it back in ten hours. Step on it."
McGee glanced out the window at the two stars. At bearing 090, all he would have to do is keep them directly to his left. Easy enough. "Aye, aye." He hit the starter.
And the two of them made it to the Beagle in eleven hours and forty-six minutes, guided by the light of the Martian stars.
CHAPTER 8
OPHIR PLANUM
DEC. 17, 2011 21:45 MLT
EVERYONE EXCEPT REBECCA was seated in the Hab's galley. Colonel Townsend surveyed the assembled group. Immediately upon her return to the Beagle, the biologist had locked herself in the lab. She had been in there for the past sixteen hours, refusing to speak to anyone. It was time to resolve the situation.
Townsend turned to the historian. "Do you think it was a loss of judgment to abort the rover excursion, McGee? Those stromatolites were a real find, everything she was looking for. And now..." He gestured at the locked lab door.
"I think she's cracked," Luke interjected.
Well aware of the rivalry between the two scientists, Townsend said dryly, "Thank you for your insightful contribution, Dr. Johnson. Please allow me to proceed in getting the facts of the case." He continued to study McGee.
The professor appeared miserable. He was obviously soft on Dr. Sherman. Another problem to look out for. "I don't know. She examined the green-veined samples with the microscope in the rover, and they revealed no biological structure. But she said its magnification was too weak, and that she needed to use the more powerful microscopes in the Hab. She said she had to do it before the sample could die."
"Die? Rocks don't die. You mean she thinks the green stuff is alive?"
"That's what I think she believes."
Luke slapped the table. "Well, I'll tell you what I think—that little lady is off her little rocker."
Townsend winced. "I don't need to be lawyered on the subject, Luke." And I don't need crew members trying to backstab each other.
Gwen shrugged and looked at the sealed door. "Colonel, if you want, I can disable the lock so we can get her out."
Well, at least that was a positive suggestion. He could withhold judgment until he spoke to the doctor himself.
"Why don't we give her a little more time?" McGee pleaded. "Especially when we might have an answer one way or another any moment and end all this arguing."
"Your loyalty to your crewmate is commendable, Professor," Townsend said, "but I don't see the point. She's had enough time. Get your tools, Major."
Gwen got up, but before she could exit, the lab door opened and Rebecca appeared.
What a mess, Townsend thought. She looked completely exhausted, totally spent, played out. Hardly the composed scientist he knew from just three days ago.
Rebecca staggered into the room, clutching an optical disk. Townsend helped her to a chair, into which she collapsed. She handed the disk to McGee and motioned to the video player. McGee put the disk in the slot, and a blue-green background filled the TV screen.