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Tesseract

Written by Tom Brennan

Illustrated by V. Shane

Anna came in too fast, too low.

There was a screech of tearing metal as Stheno's carbon trees gouged the hull and the flyer tilted fifty degrees. Anna's body slammed forward in her rigid suit. She stared at the flyer's shattered displays; emergency lighting and halon made every surface greasy. She tasted blood.

Before she could cancel it, the screech of the distress beacon filled every channel. She punched her harness release and yelled at the chaperone, "Get out!"

In its bulkhead nest, the skeletal steel chaperone tried to unfurl itself. A dislodged spar pinned it down. It flailed its six limbs like an upturned crab.

As Anna splashed through gushing hydraulic fluid, the flyer's hull began to crumple under the carbon tree's reflexive attack. Metal groaned. Anna upped her suit servos, braced herself against the bulkhead, and tore the steel spar away. She dragged the chaperone to the airlock, overrode the safeties, and blew both sets of doors. Halon erupted into the moon's atmosphere. Half of the outer door lay buried in the tree's surface, revealing layers of carbon and leaking electrolyte.

Anna pushed the chaperone out and rolled after it. She looked back and saw the flyer's keel buckle as the tree's branches curled around it, centimeter by centimeter.

God, she'd screwed up. She should have kept her eyes on the screens. Radar was useless on a moon where the flora absorbed every wavelength. Perfect black-body receptors, the carbon trees climbed out of Stheno's weak gravity and soaked up every particle of radiation, their flexible branches constantly rearranging themselves into perfect receivers.

And she should have killed the beacon before the tree reacted to the blast of radiation. Anna remembered exobiologist Jerabek's words: "Faced with something new, an organism will try to screw it, eat it or kill it. Sometimes all three simultaneously."

Now, Anna couldn't count how many branches had curled down. Enough to turn the flyer into scrap; the electrolyte made a good hydraulic. The emergency signal died. Then one of the branches angled toward Anna. Without the flyer's halo of radiation, the tree could smell her suit's minute emissions.

She ran to the edge of the tree's crown, a ridged plateau half a kilometer wide. Two kilometers below lay the frozen surface of Stheno. Above her, Ixion's bloated yellow globe filled the sky.

"Pilot?" The chaperone's voice crackled in Anna's helmet. "I advise—"

Anna gestured for silence. Too late. The tree detected the shortwave signal. Branches curled down, searching. Anna looked down the two-kilometer well, signed to the chaperone, then jumped.

She plummeted through viscous clouds of ethane. Black trees crowded around, the opposite of color. Beside her fell the angular spider of the falling chaperone, its six limbs jutting out. Before she flipped over, Anna fired the suit's directional jets. Nitrogen hissed and threw her forward. She adjusted the jets until her dive slowed. The chaperone copied her.

The moon's surface appeared, a world of white lakes of ammonia and ice, fields of carbon dioxide snow. Anna aimed for open ground.

With fifty meters to go, Anna's fuel failed. She braced herself for the shock, curling her arms and legs, protecting her faceplate with her hands. She smashed into the brittle crust and swam through carbon dioxide until a claw fastened around her arm and hauled her up. Anna stared into the chaperone's sensor array.

The chaperone plugged a fiber feed into Anna's suit. "Pilot? Injured?"

Anna struggled to her feet. The fiber linked them like an umbilical cord. Down here, the trees shouldn't be a threat, but they weren't Stheno's only radiotropic organisms.

"Pilot? Orders?"

A good question, Anna thought. The adrenaline faded, leaving a nauseated hollow in her stomach. For a moment she thought she would vomit. She sipped water and took a deep breath.

Anna stood with her chaperone in a crater fifty kilometers wide. Stands of carbon trees climbed into the sky, matte black silhouettes like old photographic negatives. Beyond the hydrocarbon fog were the crater's curved walls, then open plains and mountain ranges.

Anna's heartbeat slowed. She scrolled through the suit's readouts: power, eighty-seven percent; three liters of water; air recycling undamaged. Suit temperature 17ºC. Ambient temperature -103ºC.

No food, but the survey station, left over from the first landing thirteen months before, had stores. It also had a satellite uplink. One of the other pilots, Howards or Videan, could reach Stheno in a day. Anna just had to walk thirty-two kilometers to the station and report back to the Jefferson.

But Per Hals, the EV Jefferson's engineering chief, had sent Anna to Stheno because the survey station had stopped polling. Anna hoped simply a processor or feed had burned out. She could replace them with on-site spares.

And if something else had happened? Anna pushed that thought to the back of her mind.

"Pilot? Orders?"

Anna activated her visor overlay. "We head for the station."

****

Anna tried to develop some kind of rhythm of walking on the snow, but her legs ached despite the low gravity. She'd turned off the suit's servos, since the same power supply fed her air scrubber. She had worked on Luna, Mars, Titan, Io, and Europa, and she'd worn this suit's prototypes: a rigid, vapor-coated titanium shell, with sealed neoprene joints. Light yet strong, it should protect her even if she fell into the eutectic lakes.

She could see one of the lakes now, where water ice floated in vast stretches of liquid ammonia; the solid ammonia ice lay at the bottom. Delicate pagodas of ammonium salts grew at the shores, crystalline white and yellow. Wisps of ethane drifted over the surface.

Anna imagined what it would be like below that glassy surface. Silent. Peaceful.

Mark would have enjoyed Stheno. Like Anna, he'd loved cold landscapes, ice and rock, tundra, sastrugi. They had met on Mark's first job after college, core-drilling in Antarctica. Anna had been flying the big Tereshkoff cargo choppers, coasting until an orbital pilot job came up. After Antarctica, they'd tried to follow each other's contracts through Sol.

But Anna had been delivering a study team to Titan when the Europa dome cracked. The news had taken a week to reach her.

"Pilot?"

Anna stumbled, surprised by the chaperone's voice. "What is it?"

"How are you?"

"What do you mean?"

"Your condition?" The machine sounded asexual and monotone. "Are you distressed?"

Anna glanced back at the chaperone, a plodding creature like a huge, upright cockroach. The fiber umbilical rose and fell like a sine wave. "You're asking me how I feel?"

"I can monitor somatic environment but not emotional state."

"Is this in your system?"

"My function is to protect you."

Anna laughed. She wondered what survival routines the designers had set up. "So, what could you do if I was distressed?"

A pause, then, "Converse with you. I have many diagnostic routines loaded, plus reference works on—"

"Thanks, but I prefer the quiet," Anna said. "I'll let you know if I feel lonely."

The chaperone fell silent. Anna heard only the tide of her own breathing, in and out, and the background creaks and whines of her suit. After the initial shock and her reflex reactions, a numb acceptance had set in. She almost enjoyed the hike; Stheno was a beautiful world.

She'd reached the point, on the Jefferson, where the crew's noise grated. Two-thirds of them would be going home in ten days when the ship segmented itself. The returning crewmembers were gate-happy, eager to get back to Sol. Anna could understand that and make allowances for it.

But she volunteered to stay behind. She'd spent the past three years drifting further and further away from Sol. Seemed like 47 UMa was far enough.

Had it only been the day before when Per Hals had found her floating above the expedition vessel's core docking bay? He'd called up, "Hey, Anna, you looking for work? We lost a survey node on Stheno: two days out, two back."

She hadn't hesitated. The trip meant Anna could quit the EV Jefferson for the best part of a week. "Do I have to take anyone?"

"Just a chaperone. Sign out one of the flyers and keep in touch."

Before Hals reached the exit, Anna had asked, "How did you know where to find me?"

Without smiling, Hals had said, "Simple: I checked out the remotest, emptiest part of the ship."

Per Hals would be going back home on the first trip. He'd invited Anna to visit him in Amsterdam. Per, the only crewman who had sat with Anna in the mess, despite her silence. He talked about the city, his childhood on the island of Terschelling, his family. But then Per had discovered she'd be staying behind. Thanks to relativity, Per would be over sixty by the time the second crew returned to Earth.

Now, Stheno's fog cleared and slender structures loomed up beside Anna and her chaperone, abstract mineral eruptions from the imagination of Dali or Bosch. Whorls of smooth white, contorted compounds following their own logic. Towers and ridged arches. Crystal fronds. Lattices spanning the path and dripping sharp stalactites.

Anna picked a careful path through, but her shoulder brushed against a monument, reducing it in seconds to bright shards. Anna stared at the debris for a moment before walking on. Even with the best intentions, she couldn't avoid destruction.

****

Ahead of her, two hundred meters of cliff face reared up and marked the crater's boundary. Millennia before, some planetismal had smashed into Stheno and formed the depression. The force of the impact had sent shock waves racing around the mantle to create a jagged mountain range on the opposite side of the moon.

"Pilot? Are you injured?"

"No . . . just tired."

Her quadriceps burned with lactic acid. She wished she could rub her lower back. Jefferson's medics could work on her later. She could picture herself in the ship's pool, sinking through warm water . . .

Anna stank. Despite the air scrubber, sweat trickled through her black hair and into her eyes, down her chest and back.

"Pilot? You rest here?"

"Not yet."

Anna headed for the cliff. She'd been lucky so far: she hadn't seen any geysers, even thought they preferred the element-rich craters' floors. She checked her suit: power at sixty-two percent; one-point seven liters of water; air recycling at full. Internal 21ºC. Ambient -102ºC.

She'd have to cut back on her water intake. There'd be plenty to drink at the station. And to eat. Anna focused on the lip of the crater. Twelve kilometers gone; twenty to go. She just had to pace herself.

The utter peace and solitude were addictive. Anna entered a calm, disconnected condition, almost a fugue state. Her limbs moved in mechanical rhythm. Her situation caused no worry; she'd soon be in the survey station, showered and fed. But she wished she'd had time to grab some music from the flyer.

She'd been listening to Arvo Pärt on her com-set when Per Hals had tracked her down. Minimalist music suited this world, as if the musicians had been here before any of the scientists. Some of those old composers had been alive when the Huygens probe landed on Titan—had they seen the transmitted pictures?

Anna had to rest. She gazed up at Ixion's surface—47 UMa's gas giant—at storms of hydrogen and helium larger than the Earth. Ixion had three moons, all named after ancient Gorgons, but Medusa and Euryale had lost atmosphere early in the system's formation, as Ixion's mass pulled in loose matter. Planetismals and fragments had rained down on the three moons; by chance, Stheno survived with just enough atmosphere to trap the distant star's heat.

Euryale and Medusa's elliptical orbits brought them close to Ixion; at pericentron, tidal heating wrenched at their cores. Anna wondered what would happen when Euryale crossed the Roche limit and disintegrated, torn apart by tidal forces. The three moons, locked in a complex resonance, would become two. Would Stheno survive? Or would it follow Euryale into Ixion's well? All this would be lost.

The first geyser erupted forty meters to Anna's left. The nitrogen plume ripped through the snow and widened as it rose, fanning out in silence across the sky. The airborne tesserae sparkled for a moment as they rose.

Anna fed power to the servos and started running, ignoring the pain. She didn't look back. Her heart hammered and her breath came in ragged bursts.

She had to get away from the geyser. The nitrogen and assorted volatiles didn't worry her but the tesserae did. Small carbon and mineral formations, some only millimeters across, had the same tropism as the carbon trees: any and all radiation. If they swarmed, they could clog Anna's suit, then bond like concrete.

Anna reached the foot of the cliff. She dragged air into her lungs and looked up. She'd planned to use the suit's crampon spikes and monofilament line, but she had no time for that now. She turned to the chaperone. "How much fuel do you have?"

"Twenty-six percent, Pilot."

It might be enough. "Take us up."

As the chaperone wrapped two of its manipulators around her suit, Anna looked back. The tesserae had started to fall, a horde of bright insects.

Anna lurched into the air. The cliff face filled her view and she winced, sure she'd collide. Then they were over the curled lip. As soon as the chaperone's grip loosened, Anna killed the servos and started out across the snow, striding toward the survey station under her own power.

A handful of tesserae landed on her forearm, attracted by the external control pad. They flattened themselves to the quartz panel and changed color from white to black. Three of them slid together. Where they bonded, the joints became invisible.

Anna headed for the mountain range to the north: to one side, the spire of Cathedral Peak; to the other, the Presidents, bulbous formations jutting from the sheer rock. They made good landing reference points. Anna aimed straight for them.

****

Anna woke, sure that someone had called her. Every muscle ached, just as she'd felt after cadet training in the centrifuge at Austin. She'd been dreaming of Mark but realized that she couldn't picture him clearly. She felt cheated, glad to be awake but still struggling to remember Mark's face.

"Anna?"

A man's deep voice. She must still be asleep.

"Hey, Anna? Respond."

Anna sat up. "Hals?"

"Jesus, Anna, I thought we'd lost you." Despite the time lag, Hals sounded as if he stood next to her.

"Hals? Where are you?"

"On a cargolifter midway between Jefferson and Stheno," Hals said. "We're about twenty hours away. Think you can hold out?"

Anna couldn't concentrate. Fatigue filled her like a heavy shadow. "I don't get it."

A small delay, then, "The surveysat grabbed part of your distress call and sent it through to the Jefferson. We hauled out the fastest lifter and set up a laser link to your chaperone, via the sat. Clear?"

Anna shook her head. "I guess."

"Good, because I don't want to stay on too long. It looks like your power is down to about forty percent. You're heading for the survey station, right?"

"Right."

"Then look out for us. Keep steady and don't screw up."

As the signal died, Anna realized she didn't want to explain to Hals how badly she'd already screwed up.

She stumbled to her feet. She forced one leg before the other, trying to get back into rhythm. She fell to her knees and let the chaperone help her up. Twenty-nine kilometers down. Three to go. Only three. A baby could crawl that.

She'd never been so tired, not even when that blizzard had caught her on Mount Cabot, back home in New Hampshire. She'd skied nonstop for a day, sometimes through whiteout, before finding the road to Lancaster. Her dad had called her every name he could think of for being out