by Larry Niven
Kimber waited for the stars’ return. If she was tense, Eric looked ready to lunge at his instruments. He didn’t move, he didn’t breathe. And there they were, a billion white dots sprayed across the Shuttle windows, one very bright. Trinestar, Trine’s sun.
Eric said, “I’d sell myself into slavery to know how that works.”
Then it was only a matter of moving inward, shedding velocity at half a G, staying above Trinestar’s ecliptic plane. Trinestar kept a dense, dangerous asteroid belt. Those resources would make Trine more valuable, and maybe easier to terraform.
Trine was a frozen world, a white dot becoming a white pearl. Star Surveyor II was in orbit before texture began to show. Heights and depths, a topography as rough as Earth’s done in glare white and black shadow. The tops of mountains thrust through icy swirls of white like dark pearls on a linen cloth. A gaudy egg-shaped Christmas ornament passed below, painted in fractals, white and iridescent red with huge curved windows in odd shapes. The Thembrlish. Drifting, gone.
Free fall didn’t bother Kimber when she could hold the right mind-set. She was not falling, she told herself. She was floating. Floating, looking down like a goddess on her world; and her world was good. Fifteen minutes passed before she stretched and reached for her pocket sec’ to dictate some subvocal notes.
Eric drifted forward. Kimber didn’t stop him, didn’t even speak to him. She was bored with his reserved distance.
The Thray ship drifted back…oh, of course. Eric was matching course. A tube snaked out of the white-and-crimson sphere and fumbled about until it lipped the Shuttle airlock.
Regulations required one of them to stay on board. Eric looked resentful as Kimber left him and went into the Thray ship.
She walked through a maze of twisty passages not much wider than her outspread arms, keeping to the gold carpet. Gold marked her path, and marked out gravity. If she left that path she’d be falling. Thray drifted past her, facile in free fall, ignoring her but never brushing her. Armor covered them, not pressure suits, just protection. Their joints bent oddly; otherwise, they might almost have been human. She saw only half a dozen crew before the corridor suddenly ballooned out.
Thembrlish’s viewing deck was so huge that Star Surveyor II would fit inside and leave room for seats along the wall. She followed the golden strip around and bowed to her Thray contact.
Althared’s face glowed with a milky white translucence. Veins of blue liquid moved just under the skin and pulsed through the darker blue of his mouth. Large almond-shaped eyes were inset deeply on each side of his head. When he bowed, he turned his head left, his right eye holding hers. Then he stepped forward, took her hand, placed his other hand on the small of her back and turned her and jumped.
He had big hands, long and fragile fingers. His hand covered most of her back. She couldn’t help thinking of a tarantula, and falling distracted her. She flinched violently before she got herself under control.
Althared didn’t seem to notice. He turned her so they looked out on the patterned whites and grays of Trine in a floor-to-ceiling window. Althared spoke softly, his voice audible only through the translator at his throat.
“It was once a green planet. We intend to make it so again.”
“How?”
“It would warm itself in a million years. We will not wait. We will reflect sunlight down onto the surface from a hundred thousand klicks around. We will pour heat onto the planet until the ice melts. Even as little as we like cold, we believe we can live near the equator in less than a hundred years. Most of the landmass is there. We will begin as soon as we get your positive report.” He gestured, and a hologram of Trine appeared in front of them, superimposed on the image of the real planet in the window. As it rotated, she saw the ice pull back slowly, then faster, until continents and seas emerged between two great caps of ice. “This, Kimber, is our goal. Your survey will clear us to start down that road. A base camp has been prepared. We made maps in anticipation of your arrival.”
“My world has been like this,” Kimber said. “Twice.” Eric had told her that. Suddenly she wished she had listened more carefully.
“Early in its evolution, I expect.” Althared wasn’t interested.
The map was still up. The roughness under Trine’s white blanket, lines of mountain ridge, clearly shaped a large and two smaller landmasses, all near the equator, leaving vast white curves north and south.
Her thoughts caught up. Training told Kimber to choose the base camp. She grimaced, then asked, “Where did you put us?”
She didn’t see Althared’s hand move, but the map zoomed on a white nothing, well north of the equator. Two red dots became domes painted red and black, like the pattern that marked Thembrlish itself. They squatted in a sprawl of temporary roads, white on white. Kimber blinked.
“Althared? Did you put the base camp on an ocean?”
“Yes, that must once have been an ocean. It made an easy landing field.”
“But what can you possibly expect us to learn there?”
“Here and here are islands not far below the ice. Peaks protrude here. No? Then choose a place. We will move the camp.”
Irregularities sprawled along the equator, touches of shadow under the ice. Two big continental masses, narrowly separated, reaching no more than fifteen degrees north and twenty south. A third mass, far west and much smaller, still equatorial. A handful of islands farther north. They’d have Thray names…would they? Kimber tagged them. Blotch was the size of Asia or larger. Internal magma flows had stretched the next largest mass like taffy, she thought, giving it the curve of an integral sign. Black mountain peaks followed the spine. Integra, she called it. The shadow shaped like nothing in particular, she called Iceland. What the hell, she could change it later.
Kimber pointed at near random, below a black ridge of mountain peaks, Integra’s spine. “There.”
“Direct overhead sunlight on such a vastness of ice might hurt your vision. Too much of this world’s atmosphere has frozen out. The sunlight is not thinned.”
She looked at Althared’s profile. It never showed anything at all. She’d been told that the human face evolved to convey messages; it was not so for other species.
“I brought blue blocker glasses,” she said.
“Moving camp will cost us perhaps thirty hours. Return to your ship.”
“You’re back?”
Kimber sounded defensive even to herself. “They put our base camp in the middle of an ocean!”
“Show me.”
“What was I supposed to find?”
“Mmm.”
“So they’re moving the camp.”
“Where? Show me.” He’d forgotten who was in charge again, but at least he was talking. “That looks mountainous. Was it your pick?”
“Yes. Why?”
“Oh, I’d have…here.” He pointed at the center of a sketchy Y, white on white, hard to see. “Might be two rivers converging. The point is, you picked it.”
“Eric, I told Althared that the Earth has been frozen twice. You told me that, didn’t you? Years ago? Frozen right across the equator, pole to pole, you said.”
He grinned. “I thought you’d stopped listening.”
“I didn’t stop listening. I stopped helping you do your homework when I had my own courses. But is it still true? Since the aliens came, the facts change pretty fast.”
“They sure do. Captain, do you see where the continents lie? Right along the equator?”
“Yes.”
“What we used to know, what every geologist knew, was that the Earth has a stable state. Ice ages come and ice ages go, but if we ever froze all the way, the albedo, the Earth’s reflective index, would shoot up near a hundred percent. We’d still be getting sunlight, but it would all bounce off the ice, right back to space. We’d be frozen forever.”
“Uh-huh.”
“We knew this, like we once knew that continents don’t move. Then some geologists found evidence that Earth was fro
zen. Twice. The record is in the rocks, but what they knew was crazy. If the Earth was all one glittering icy pearl, how would it ever warm up?”
Kimber speculated. “The sun could flare, if you wait long enough. Or a giant meteoroid impact?”
“Twice? Oh, all right, but try this. You know that carbon dioxide is a greenhouse gas?”
“Sure, and water vapor too.”
He waved it off. “Water vapor freezes out in an ice age. Rock absorbs carbon dioxide by making limestone. But if you cover whole continents with ice, you’ve covered the rocks. Limestone formation stops, carbon dioxide builds up, heat gets trapped, and that’s how an ice age ends.”
“Oh. Oh. What if the continents are all on the equator?”
“Yes! Yes, Captain.” Was it that startling, that she should have an insight? “On Earth it was all one continent then, but it’s the same with Trine, the ice cover is nearly complete before limestone production slows down. Now the only question is, how are the Thray going to warm it?”
“Sunlight,” she said. “Mirrors. From a hundred thousand kilometers around, Althared said.”
“Ten-to-the-fifth klicks radius? That’s…Kimber, it’s pi times ten-to-the-tenth, that’s thirty billion square klicks of mirror.”
She shrugged.
“Kimber, how do you talk to a Thray?”
“Althared is the one who talks. I don’t know their language at all. There are heat flashes in it, and some fine muscle structure around the breathing orifice—”
“I meant, he looks so fragile.”
“Fragile. Right. Think about what we’d look like to a gorilla.” Ugly? Had Eric been about to say ugly? That was the first thing any student unlearned.
Eagle was a Wayfarer Minim, Pillbug built, a sealed hockey puck with a small cabin and cargo lashings bolted on. It rode in the bay of Star Surveyor II. There were four seats, one built for Thray. Two were folded down.
Althared was wearing a full EVA pressure suit. He looked like a cluster of clear balloons and took up a lot of room. At Althared’s insistence, Kimber too was in “Moonwalker” pressure gear. She’d packed a wealth of skiing and cold weather equipment in the cargo hold, but in Althared’s view this world was nowhere near that friendly. She’d try it his way.
Althared pointed out the base camp, two big domes dropped by the Thray’s heavy lifter. When they got close enough she saw four of the large slow insulated vehicles called Skidders. Reflectors marking the survey boundaries bounced the midday sun in multiple directions. From the sky, the reflections looked as bright as artificial lights. As they climbed out of the Shuttle, Althared darkened his faceplate against ice blindness. Kimber flipped her filter down.
Now it begins. Sweat trickled down the back of Kimber’s neck.
By strict Bio/Geological Survey doctrine, Kimber was supposed to be neutral. Still, the Thray were powerful galactic citizens, and she felt like a small child wanting to please a parent. Humans were so new at this, how else was she supposed to be?
Luckily, all she had to do was use what she’d learned in school, prove Trine had not been recently inhabited by a sentient species that might have a valid right to it, and that the planet held no insurmountable intrinsic threats to life. It should be easy. The Thray had already done the preparatory work. She would review their notes and do her own independent survey, and the Institute would grant their claim. Kimber and Eric would have real jobs well-done for their résumés.
Thray biology required heavy insulation against the constant cold. Althared worked with her for three days, but she could see his discomfort. He showed her how to read Thray maps and made sure she knew how to operate the ice Skidder that would be her transportation. She looked forward to every morning, even though she still felt like a child compared to the solemn and brilliant Thray she worked beside. Althared shared information with her about Trine’s dry, cold climate and ferocious windstorms. He’d made sonar maps of the layers of ice around the base camp. He was willing to discuss the terraforming process they would use. He asked numerous questions about Earth and humans, but he already knew a lot about human history.
Kimber fell into bed too tired to undress each night. The fourth morning, she found the courage to announce she would begin going about on her own.
Althared politely withdrew, and Kimber finally felt in charge and free to start work. She would be in constant instrument contact with Eric, working almost side by side if not in the same physical space. She hoped it would strengthen their working relationship.
The next morning she went out without a pressure suit.
It was no-kidding cold. Kimber was geared up for skiing in Nevada or Vermont: two layers of everything, more than that under her parka, a ski mask and fake fur hat with a brim, Blue Blockers, real cross-country skis…it was enough. She’d wondered if scents in the air would tell her anything. She smelled nothing but the cold. But she could move more freely, she could snack as she moved…and she felt closer to Trine.
She spent two weeks following the Thray maps. Hundreds of detailed readings were beamed between her Skidder and the ship daily using straight sight, handheld tools, and the instruments in Star Surveyor II. It would all go to Eric and into the Verification Link.
Where she could reach rock, she found fossils of long-dead plants. The Thray already had an extensive collection; but some of the species she found weren’t in their records. She named them. Now they were hers.
She traveled alone except for her link to Eric. She must be extremely visible to the orbiting Thray ship, neon orange parka on glittering white; but she saw Althared only periodically, and always at base camp.
Kimber shuttled samples up to Eric. He did not discuss interpretations of her finds. They talked daily, but only briefly unless they were calibrating instruments on the ships.
She remembered that they’d had the same interests when they moved in together. It was wonderful. They talked…he talked, mostly, but she learned. That was when their studies were the same. Going into their junior years, their courses had changed. He would still talk about what interested him, but now it was a distraction she couldn’t afford. Finally, she’d said so. For a long time, he hardly said a word to her.
Now he’d become the talker again, losing a touch of the reserve. Shutting a man up was supposed to be easy. Dammit.
She tried. “The winds are ferocious. I’d guess there’s nothing to stop it, no barriers, just flat ice across most of the planet.”
“Mmm.”
“The carbon dioxide, did you notice? Three percent.”
“Yeah. Strange. No variation?”
“About a percent. The wind mixes the air up pretty good. The continents are all under tons of ice, right? No limestone formation. Where’s all the carbon dioxide?”
“…Right. Can you spare me for half a day? I can do a pole-to-pole orbit and see if the CO2 is freezing out.”
“Go for it.”
The next morning Kimber took her Skidder farther out than before. Althared had indirectly requested she stay inside the survey boundaries, and she had until now. But the sonar map showed greater area, the winds had eased off, she was on schedule, and she had legal access to the whole planet. She left quietly after filing a vague plan with the base camp computer.
Kimber drove out toward a simple sector between mountains and probable ocean, colored yellow on the map to represent tundra fields. Her hope was to get a horizon view and maybe dig into the permafrost looking for evidence of past warmth. The first hour she rode across bare flat fields of ice. Dips and rises in the terrain made the horizon line elusive, and she traveled fast without stopping for samples. In two hours she’d gone twice the distance her filed plans called for.
She came over the top of a low hill and found herself dropping fast, manhandling the Skidder through ravines of sharp clear ice punctuated with dark gray and black upthrust rock. Twice she could only move forward by using the Skidder’s weight to push through thin walls of ice: running water frozen in bright she
ets, like waterfalls trapped by winter back home. She emerged from the twisted chasms into a narrow white valley, and stopped to check her map. Getting lost now would be bad.
She hadn’t made a mistake: the coordinates she showed were marked as tundra. Surprising…but the most extensive Thray mapping had been done elsewhere, on a frozen ocean.
“Eric?” she called.
“I’m back. Where are you? You just lost three hundred meters of elevation.”
“I’m in a canyon. It’s not on the Thray map, but it’s big. Different too—I can see more rocks and less ice.”
“Glad you’re OK. Kimber—the poles are too warm to freeze carbon dioxide. I don’t know where it’s going.”
“OK. Later. Please scan the area south and east of me.”
“Oui, mon Capitaine!”
She sent him up a few still pictures to give him her viewpoint, and to show him the canyon’s stark beauty. Then she flicked the Skidder back into forward gear. Traction was good and she relaxed and watched the scenery. Tall spires of rock stuck up in the canyon wall, encased in ice. It was a strange formation—usually a long freeze like this would not make such straight walls, but maybe a river had run through here at some point, cutting the ice down and leaving the flat valley she was traveling through.
Eric’s voice sounded in her ear. “OK. I can see where you are. The canyon goes for two miles. Scanning. Hey—some of that looks like cavities. You might be above water.”
“Not water. At these temps, it would freeze anywhere near the surface. Air pockets?”
“They’d be big.”
She looked carefully at the ice ahead of her but it seemed to be all the usual shades of white. Then she had to push the Skidder through another thin sheet of frozen ice. She found herself staring at thick ice over a rock overhang. Below, the distinction between ice and rock faded into deep shadows.