Frost That Turns Left

Cold Locker

The drone came home with frost on its teeth. Sunniva Achterberg watched it on the bay camera as it nosed into the cradle, its intake scoops rimed white, the little sample cartridge glittering in the work lights like something pulled from a freezer at the back of a shop. Below it, filling the lower half of the window, Mirrin turned its scarred face toward Aurelle, and the striped giant hung beyond the moon so large that it no longer looked like a planet at all. It looked like weather.

"Cradle's latched," Priya said over the intercom. "She's cold. Nice and cold. You want the cartridge straight through?"

"Straight through. Don't let it warm."

"I have never once let your ice warm." A pause, the clack of the bay's transfer lock. "Vial's sitting open in the locker, the pretty one. Fused quartz, titanium sleeve, made it with my own two hands on the way out here, so if you crack it I'm going to be personally hurt."

Sunniva smiled at the console and didn't answer. On the transfer display the cartridge crept through the airlock, then into the cold locker beside her station, a squat insulated cabinet that hummed against her knee. The manipulator arms inside were slow and careful. They scraped frost from the cartridge into Priya's vial, capped it, and pulled the seal down until the gauge settled. A fraction of a plume that had risen out of Ebbing Crater a few hours ago now sat in a tube no longer than her finger.

It was supposed to be the dullest part of the day. The Halyard had been circling Mirrin for weeks, drawing its map line by line, and the plume samples were a courtesy line in the survey plan: catalogue the salts, note the volatiles, move on. Sunniva had flown the drones through a dozen plumes on three moons. They brought back brine and ammonia and the occasional ugly little hydrocarbon, and she wrote it all down, and nobody back at Taldor Relay Station read past the summary.

She fed a sliver of the frost into the spectrometer and started the run.

Behind her, the hatch to the flight deck sighed. Kasimir Wendell drifted through with two drink bulbs tethered to his wrist, his hair flattened on one side where he'd slept against a headrest. He held one bulb out without looking at it, and she took it without looking at him, and that was the whole of it. They had stopped making anything of these small exchanges a long time ago, or had agreed to pretend they had.

"Mapping pass twelve is clean," he said. "Okello wants the trim before the terminator."

"He'll have it."

"He'd like it ten minutes ago."

"He'd like everything ten minutes ago." She sipped. The tea was too sweet, which meant he'd made it for himself and given her his. "Tell him the plume run's going now."

Kasimir hooked a foot under the rail and stayed. He liked to watch the spectra build, though he said he didn't understand them. She suspected he understood them fine and simply liked watching her watch them.

The first traces came up the way they always did. Water, overwhelmingly. Chlorides. A familiar ladder of ammonia lines. Then a cluster of heavier organics, which was interesting but not shocking; Mirrin's ocean had been cooking under its ice since before anything on Earth had a spine. She switched the instrument to its polarimetry mode almost out of habit, sending polarized light through the melted sample to see whether it twisted.

Chemistry without life makes molecules in mirror pairs, left and right in equal measure, and the light passes through them and comes out the way it went in. That was what she expected. That was what she had seen every time.

The light came out turned. Hard to the left.

Sunniva set the bulb down on its tether and let it float. She did not say anything. Her face, she was fairly sure, did nothing at all.

"Problem?" Kasimir said.

"Calibration drift, probably. The cell's been running cold."

It was a plausible lie, which was the worst kind. She pulled the reference standard from its clip, a sealed blank with no rotation at all, and ran it. Clean. She ran a known left-turning standard. It turned exactly as far as the label said. She flushed the cell, flipped its orientation, and loaded a second sliver of frost from the vial.

Left.

Her pulse was going in her throat. She could feel the place where her collar touched it. Instrument artifacts had fooled better people than her; she had sat on review panels and helped tear apart claims like this one, written polite, devastating comments about contamination and thermal gradients and wishful baselines. She knew what it looked like when someone saw what they hoped to see. She refused to be that person in front of Kasimir, who would believe her, and in front of Okello, who would not.

"Sunniva." The commander's voice came through the deck speaker, even and unhurried. "Trim burn in a few minutes. Anything from your side I should know about?"

She looked at the twist on the screen. The left-handed curve sat there like a signature on the bottom of a letter.

"Nothing that changes the burn," she said.

"Good. Kasimir, I need you up here."

Kasimir unhooked his foot. At the hatch he paused, one hand on the frame, and she felt him looking at the side of her face. She kept her eyes on the console. He went.

Through the open hatch she could see Okello Rasmussen strapped into the command seat, broad shoulders squared to the board. He lifted the burn key from his lanyard, a stubby piece of anodized steel stamped at the Taldor yards before launch, its edges rubbed bright from years of thumbs. He fit it into the console and turned it, and the arming light went from amber to green. Sunniva had watched him do this a hundred times and it always looked faintly ceremonial, like a man winding a family clock.

"Nine days," Okello said to no one in particular, which was how he said most things. "Nine days to the tanker window and every one of them already spoken for. Let's keep it that way."

"Copy," Kasimir said.

The drive pushed. It was gentle, a soft hand at Sunniva's back that pressed her into the station straps, and the loose drink bulb swung on its tether and settled against her arm. Through the deck she felt the faint shiver of the engine, nothing like the roar she'd imagined as a student, only a tremor in the frame that told her the ship was doing something. Then it stopped. Okello turned the key back and slid it onto the lanyard and tucked it under his collar.

Priya floated up from the bay a minute later, wiping her hands on her thighs, grease on one knuckle. She glanced at the cold locker, then at the screen, then at Sunniva.

"That's a funny shape."

"It's a cold cell. They do funny shapes."

"Huh." Priya leaned in, squinting. "I can pull the cell and bake it out tonight if you think it's the heater. Bad heater'd explain it. I've been fighting that board since we left the yards."

"Maybe tomorrow."

"Your call." Priya hesitated, then pushed off toward the galley. Over her shoulder she said, "I've been running the return tables again, by the way. Aurelle's got some weird options on the far side if you squint. None of them are useful. I just like looking."

"Nobody's squinting at anything," Okello called from the flight deck. "We go home on the tanker."

"Yes, Dad."

The ship settled into its ordinary noise. Sunniva sat in it and listened to her own breathing and looked at the vial behind the locker's little window, frost clouding the inside of the quartz. She wrote in the log: Plume sample, Ebbing Crater. Organics present. Polarimetry inconclusive pending cell bakeout. Every word of it true. None of it the truth.

Proof did not come from one run, or two. It came from different ice, from a different pass, taken at a different hour through a different part of the plume, and the plume did not stay put. If it was real, it would turn left again. If it was the heater, it wouldn't.

She called up the drone bay. Three drones sat in their cradles, the one that had just come home still shedding frost from its scoops in slow glittering flakes that drifted off in the bay's air and stuck to the walls. She skipped it and selected the next one.

In the flight plan field the cursor blinked, waiting for a reason. Mapping redo. Instrument check. Volatile survey. Any of them would have done. She left the field empty and keyed the launch, and below her on the bay camera the outer doors parted onto Mirrin's dark curve, and the little drone slid out of its cradle and fell away toward the crater, small and quick and unexplained.

Orbit Change

The second drone came home a little before the ship's morning, and Sunniva was already in the bay with her hair tied back and her sleeves pushed up, waiting for it. It nosed into its cradle and the clamps took it with a soft knock she felt through the bulkhead under her palm. Frost hazed its scoops. She bagged the cartridge before the bay air could get at it and carried it forward against her chest, the way she used to carry eggs home as a girl, though nobody aboard had seen an egg in two years.

Priya had pulled the polarimeter cell overnight as promised and baked it out. It sat back in its housing now, the heater board replaced with a spare she'd been saving for something worse. A strip of tape across it read DON'T BLAME ME in marker.

Sunniva loaded the new ice. She ran it. She ran it again, then ran a blank, then ran the old vial's frost against the blank to be sure the instrument still agreed with itself. It did. The trace climbed the screen and leaned, the same direction as before, hard to the left.

Different ice, taken at a different hour from a different shoulder of the plume, kilometers from the first pass. A new heater. The light turned left anyway.

She sat with both hands flat on the console and did not let herself say anything out loud, because if she spoke she might laugh, and if she laughed she might not stop.

"You're doing the face."

Kasimir hung in the hatch with a bulb of tea in each hand. He'd shaved, badly; there was a nick under his jaw he hadn't noticed.

"I don't have a face."

"You have a face. It's the one from the Ganymede seminar photos. Before you told the room it was all contamination." He floated over and set a bulb against her knuckles until she took it. His fingers stayed a moment longer than they needed to. "Show me."

She showed him. He didn't understand polarimetry beyond what any pilot picked up, but he understood the two traces lying one over the other, and he understood the blank sitting flat between them.

"Okello needs to see this," he said.

"Okello's going to say no."

"Probably. Show him anyway."

---

They gathered on the flight deck because that was where Okello lived. He listened with his arms folded and his feet hooked under the rail, the burn key a small lump under his collar. Priya drifted in behind them chewing something, and stopped chewing when she saw the screen.

"That's my heater," she said.

"That's your new heater."

"Huh."

Sunniva laid it out plainly. Two passes through the plume. Two samples taken far apart in space and time. A clean instrument. Frost that carried molecules built one-handed, the way life on Earth built them, the way nothing else she knew of bothered to.

"It could still be a lot of things," she said. "Some mineral surface that sorts them. Something in the vent rock we've never seen. I'm not saying it's alive." She heard her voice catch and steadied it. "I'm saying it isn't the instrument. And the drones can't tell me more. They grab whatever's floating. I need ice from the source, from the rim, before it's been out in the sun and the radiation for an hour. I need to stand where it comes out."

Okello looked at the traces for a long time.

"We've got nine days to the window," he said. "The tanker doesn't wait. It can't wait. It's on its own track and it has its own people. If we're not at the rendezvous, there is no second tanker."

"I know."

"Getting down to Ebbing means a lower orbit. Plane change, phasing, then climbing back up after. It eats propellant and it eats days." He unhooked one foot and turned to Priya. "Tell her."

Priya swallowed what she'd been chewing. She pulled the ship's numbers onto the side screen and did it the honest way, out loud, her finger tracing curves around Mirrin's dark bulk. "If we drop today, one landing, short stay, straight back up... we'd be looking at seven days to the window instead of nine. Margins go thin but they're still margins." She hesitated. "Two landings, I can't make it close. Not to the tanker."

"Not to the tanker," Okello repeated, and gave her a look. Priya shrugged and looked away first.

"One landing," Sunniva said.

"One landing is still a landing on a rim nobody has mapped closer than our own passes. Next to a vent that throws ice hard enough to reach orbit." He kept his voice level, which was worse than if he'd raised it. "I've done this a long time. I have brought everyone home every time. That isn't luck. That's me saying no to good ideas."

"Is this a good idea?"

"It's the best one I've heard in years. That's what worries me."

Nobody moved. Kasimir was watching the floor. Sunniva made herself wait. She'd learned long ago that whoever filled a silence first usually lost the room, and she also knew Okello well enough to see he wasn't really deciding anymore. He was counting what it would cost him if he was wrong.

"Kasimir," he said finally. "Can you put the lander on that rim?"

Kasimir took his time. "There's a flat shelf on the north lip, upwind of the main vent. Well. Upwind isn't the word. Away from the throw. If the ground's what it looks like on the radar, yes. If it's crust over a hollow, I find out the hard way." He glanced at Sunniva and away again. "I'd fly it."

Okello unclipped the lanyard from under his collar and turned the steel key over in his fingers. Its etching had gone soft and shiny where years of thumbs had worn it.

"One landing," he said. "Short. Kasimir has the final call on the ground and I have the final call on everything else. If I say we leave, we leave, sample or no sample. If anybody gets hurt, we're done. No arguing on the radio. Agreed?"

"Agreed."

"Say it like you mean it."

"Agreed, Okello."

He nodded once and turned to his console, and that was the whole ceremony.

---

Priya built the vial in the workshop while the ship rotated for the burn.

Sunniva watched from the hatch, because she couldn't sit still anywhere else. The workshop smelled of hot metal and the sweetish dust of the quartz blank. Priya had a cutting loupe pushed up on her forehead and her tongue tucked into her cheek. The lathe hummed. The titanium sleeve came off it bright and warm, and Priya caught it in a soft glove before it could drift and turned it under the light, checking the threads.

"Same as the first one," she said. "Only I'm putting a better seal on the cap this time. The first one I made in a hurry on the way out. I didn't think anyone would ever actually fill it with anything interesting."

"And now?"

"Now I think you'll fill it with the most interesting thing anybody ever put in a jar." She fitted the fused quartz inside the sleeve with care, eased the cap down, and set the whole thing in the vacuum fixture. The pump labored, then quieted. She checked the gauge and grinned. "Tight."

She held it out. It was no bigger than a finger, cold already from the fixture, and Sunniva took it in both hands.

"Thank you."

"Don't thank me. Bring it back full." Priya rubbed the grease off her knuckle with a rag that only moved it around. "And don't let Kasimir do anything brave. He gets that look."

"What look?"

Priya just raised an eyebrow, and Sunniva found she had nothing to say to that.

Out on the flight deck Okello called them to stations. Sunniva stowed the empty vial in a padded slot of the sample case and strapped in beside Kasimir. Priya took the engineering seat and murmured numbers to herself, then muttered something about the far side of Aurelle that nobody answered.

Okello slid the key into the console and turned it.

The drive woke. There was no roar, only a firm, even hand pressing them all back into their seats, and a faint shiver in the frame that Sunniva felt in her teeth more than heard. On the forward screen Mirrin rolled under them, grey and fissured, bright where the ice was fresh. Far around its curve the plume stood up off Ebbing Crater, a pale thread catching the light of Aurelle, glittering where it climbed out of the shadow.

Kasimir's hand found the rail between their seats. Hers was already there. Neither of them looked down.

The burn ended. Okello pulled the key and hung it back on the lanyard and said nothing at all, and the Halyard, lighter now by a few days of everyone's future, began to drop toward Ebbing Crater.

Ebbing Crater

The lander settled onto the north rim shelf so gently that Sunniva only knew they were down when the dust rose past the window and kept rising, a grey veil that took its time falling back to Mirrin. Kasimir kept his hand on the throttle a moment longer than he needed to, the way he always did, then let it go.

"Ground's good," he said. "Clock's yours. Short means short."

"I know what short means."

"I know you know." He was already unbuckling. "I'm saying it so Okello hears me say it."

Okello's voice came down from the Halyard, clean and close. "Heard. Seven days, people. I'd like to keep all of them."

They cycled out together, Priya first with the drone case hugged to her chest, Sunniva behind her with the sample case clipped to her hip. The shelf was a broad lip of old ice, crusted and ridged, dark with the dust of a long time. Below it the crater floor fell away into shadow. Rising out of that shadow, closer than any screen had prepared her for, stood the plume.

It made no sound. Of course it didn't. But she felt it anyway, as a pressure behind her eyes, a column of frost climbing silently out of the dark and catching the light of Aurelle so that it glittered at the top and went gold at the edges, then thinned to nothing against the black. Grains of it were falling back around them, a fine slow glitter that settled on her visor and stayed.

Kasimir walked the shelf in long, careful, low-gravity strides and planted the marker beacon where the orbital survey said the ice was still thick. Its light blinked green against the grey. "This is the edge," he said. "Everything on this side, we trust. Everything on that side, we don't."

Priya unfolded the drone, ran her thumb along its intake, and sent it up. It rose on soft puffs of cold gas, a dark speck against the shining column, and drifted toward the vent field below the lip.

Sunniva knelt and dug. The frost on the shelf came up in grey crumbs, old and dark and baked by radiation. She ran it through the field spectrometer anyway and watched the result fill the little screen on her wrist. Left again. Faint, muddied, but left.

"Drone's sampling," Priya said. "Reading's in. Same as before. Same as both before."

Three times now, from three directions. Sunniva stared at the old frost on her glove and knew it wasn't enough. Every reviewer who ever lived would say the drones shared a manufacturer, an intake design, a calibration routine, a flaw. They'd say the shelf frost was too old, too altered, contaminated by whatever had rained on it for ages. What she needed was frost that had come up out of Mirrin an hour ago, untouched, sealed in her own hand.

And there it was, past the beacon. The vent lips below the shelf were bright white, crusted with new frost, almost blue in the creases.

She stood.

"Sunniva." Kasimir's voice, very level.

"It's a few steps."

"It's past the flag."

"The shelf frost is useless. You know it's useless. If I bring back old ice, they'll say it's old ice." She was already moving, stepping wide around the beacon. The ice under her boots felt no different. That was what frightened her, later, how normal it felt. "The fresh frost is right there."

"Then I'll come with you," Priya said.

"Priya, no."

"You need two hands to scoop and two hands to cap. I built the seal. I'm the only one who's sealed it." Priya bounded past her, light and quick, and crouched at the lip of the vent field before Sunniva could argue. "Come on. Short means short."

Behind them, Kasimir said nothing at all, which was worse than anything he could have said.

The fresh frost came up in clean bright flakes, fine as flour. Sunniva tipped it into the vial with a scoop that shook more than she liked, then held it out. Priya took it in her left glove and fitted the cap with her right, turning slowly, feeling for the threads.

Sunniva felt the ground move before she saw it. A shudder came up through her knees, then a long sideways slide, as if the shelf had shrugged. No sound came. Only her own suit, creaking faintly in her ears, and the soft hiss of her breathing.

Between them and the drone, the ice split.

It opened like a seam pulled apart, a dark line running fast along the lip, and out of it came a sheet of white, a burst of vapor and ice crystals that rose in perfect silence and fanned apart in the sunlight. The drone, hovering low to sample, tipped into the jet. It spun once, a dark fleck in all that glitter, and dropped into the fissure. Its signal stuttered on Sunniva's wrist screen and went flat.

Priya had gone over sideways when the ground slid. She put her hand down to catch herself, her right hand, the one not holding the vial, and the hand came down on the lip of the fissure, right in the vent.

Her scream filled the channel.

Sunniva saw it happen and could not make sense of it for a moment. A thin spray of ice crystals was fanning out from Priya's wrist ring, glittering, sideways, wrong. The glove seal had failed. Her suit was venting.

"Glove breach," Priya gasped. "Glove... I've got a breach..."

Sunniva grabbed her by the shoulder harness and hauled. Priya came up off the ice too light, too fast, and they both nearly went over. The fissure was still widening at the near end, crawling toward them, and the white sheet kept climbing out of it.

Then Kasimir was there. He came across the shelf in great flat leaps, past the beacon without slowing, and had Priya's wrist in both his hands before Sunniva even saw him land. He slapped the emergency patch over the seal and wound the cinch tight above it, hard, so that Priya cried out again.

"Holding?" Okello, from above. "Kasimir, is it holding?"

"Mostly." Kasimir didn't look up. "Priya, talk to me. Tell me your name."

"You know my name, you idiot."

"Good. Keep insulting me."

Sunniva looked down. Priya's left hand was still closed around the vial. The titanium sleeve had a crack running down one side, bright and jagged, where it must have struck the ice as she fell. Through the gap Sunniva could see the fused quartz, and inside it, the fresh frost.

Was the quartz whole? She couldn't tell. If it had cracked, the frost would already be leaving, slipping away as vapor, and they would carry home an empty jar and a ruined hand.

"Give it to me," Sunniva said. "Let me check the seal."

"No." Priya's fingers tightened. "It's mine. I made it. If it's leaking, I'll know before you do."

"Leave call," Okello said. "Now. All of you."

Nobody argued. Kasimir got Priya's arm over his shoulders and Sunniva took the other side and they half carried, half flew her back across the shelf, past the green blink of the beacon, which seemed so small now, so far from where they'd been. Behind them the plume kept rising, untroubled, glittering, as if nothing whatever had happened.

In the airlock Kasimir cut the glove away. Priya's hand was white and waxy to the second knuckle, the skin stiff and strange where the cold gas and the vacuum had found it together. She didn't look at it. She looked at the ceiling and breathed through her teeth while he worked a warming sleeve over it and pushed something into her arm.

"That'll take the edge off," he said.

"What edge? I can't feel my hand."

"You will. That's the part I'm taking the edge off."

Sunniva knelt in front of her. "Priya. I'm sorry. I should never have..."

"You'd have gone alone." Priya's eyes came down from the ceiling and found her. "So I went too. That's all."

Okello's voice came through again, slower now, careful. "We've missed the ascent slot. I have to bring the Halyard around the long way to catch you, and that eats the margin. When you're aboard, we're at three days."

Sunniva closed her eyes.

"Two drones," Priya murmured, half to herself, drifting a little now. "Down to two drones. I'll have to... the far side of Aurelle... if we just..." Her voice trailed away into breathing.

Kasimir strapped her into the couch, checked the cinch on her wrist, checked it again. Then he turned and looked at Sunniva, and for a moment neither of them said anything. His face behind the visor was grey with something she had never seen on it, and she understood that she had done that too.

"Sit down," he said quietly. "Hold on to her."

She sat. She took Priya's good arm, the one still curled tight against her chest, and felt the hard shape of the vial in that fist.

Kasimir took the controls. His hand rested on the throttle for one long moment, the way it always did, and then he eased it forward. The lander shivered and rose, dust spilling away beneath it, and the shelf fell back, and the green beacon, and the dark line of the fissure still breathing white into the sunlight. Priya's fist stayed closed around the cracked sleeve all the way up, pressed against her heart, and she did not open it.

Medbay Light

The medbay lights had been turned down to their night setting, a pale amber that made everything look older than it was. Sunniva hung by the foot of the bunk with one sock hooked under a rail and watched Kasimir unwrap the warming sleeve from Priya's hand. He did it slowly, a turn at a time, the way he might lift the cover off something that had been left out in the rain.

The skin underneath had gone from white to an angry, mottled red. Blisters had risen along the first two fingers, tight and glassy. Priya looked at them this time. She'd been looking at them since she woke.

"That's good," Kasimir said. "Red is blood. Blood is good."

"It's ugly."

"Ugly and alive. I'll take ugly and alive." He pressed a gloved thumb gently against the pad of her ring finger and watched her face. "Feel that?"

"Like a wasp."

"Better than nothing." He began rewrapping it in a lighter dressing, something cool and gauzy that clung to itself. Sunniva watched his hands, because watching them was easier than watching Priya, and she had not slept, and every time she closed her eyes she saw the fissure breathing white.

The hatch slid open. Okello pulled himself through and caught the frame with one hand, and he did not come any farther in. He wore the same shipboard grey he always wore, but the collar was unbuttoned and his face had the scraped look of a man who'd been awake as long as she had.

"How is she?"

"She's right here," Priya said.

"How are you, then."

"Keeping the hand. He says."

Kasimir nodded without looking up. "Probably all of it. We'll know in a week whether the tips come back."

Okello let that sit. Then he looked at Sunniva, and she knew what he was going to say before he said it, because she had been saying it to herself since the lander docked.

"We burn for the tanker tomorrow. First good slot after the next pass." He kept his voice level. "I've already set the sequence. Whatever's in that vial comes home in the cold locker, and someone at Taldor Relay Station can bake it and argue about it for ten years. We're done here."

"The sleeve's cracked. If the quartz went too, if anything got in, then by the time anyone opens it..."

"Then it'll be contaminated, and you'll have the drone runs, and they'll be enough or they won't." He didn't raise his voice. He never did. "I let you go down because you showed me two clean results and a real question. I gave you one landing. You had it."

"I know."

"Priya paid for it."

"I know, Okello."

"Then you know why I'm not asking."

The air handler ticked over somewhere in the bulkhead. Kasimir finished the dressing and tucked the end under and didn't look at either of them.

"There's another way," Priya said.

All three of them turned. She was fumbling at the slate clipped to her bunk with her left hand, the wrong hand, clumsy with it, and she had to try twice before it woke.

"Priya, you need to sleep."

"I did sleep. Then I didn't." She pushed the slate toward Okello and it drifted halfway across the bay before he caught it. "Around Aurelle. Not away from it. You go in low on the far side, let the planet throw you, and you come out pointed at Taldor. No tanker. You don't need the tanker if you're not in a hurry."

Okello was reading. Sunniva watched his eyes move down the slate and stop and go back up again.

"This is months longer."

"It's slow. I said slow."

"It leaves us almost nothing in the tanks."

"Almost nothing is more than nothing." Priya let her head fall back against the padding. "I ran it three ways. It closes every time. Barely. You'd want to check it. I'd want you to check it, I did it with the wrong hand and a lot of whatever Kasimir put in me."

"If anything goes wrong on that route," Okello said quietly, "there's no one coming. You understand that. The tanker is the only other ship out here. Miss it and we're alone the whole way."

"We're alone now."

"Not like that."

Sunniva had pulled herself closer without meaning to. Over Okello's shoulder she could see the curve Priya had drawn, a long swing down into the shadow of Aurelle and out again, and the tiny bright notch near the bottom where the drive would fire. It was beautiful in the way that only a thing that might kill you could be beautiful.

"It buys time here," she said. "Doesn't it. If we're not chasing the tanker, we don't have to leave tomorrow."

"It buys a little." Priya's eyes were closing. "Not a lot. Enough for one more drone, maybe. We have two drones. I'd rather keep one."

"Priya."

"Mm."

"Why did you do this?"

But Priya was already gone, her breath lengthening, her bandaged hand floating up a little from the blanket until Kasimir caught it and tucked it down under the strap. Okello looked at her for a long moment. Then he looked at the slate.

"I'm going to check her work," he said, and went out, and the hatch closed behind him.

The bay was very quiet. The amber light lay on everything. Kasimir dimmed the panel over Priya's bunk and pushed off toward the supply cabinet and started putting things away, the scissors, the spare dressing, the little vials, each in its slot, each slot latched. Sunniva watched him do it. He did it twice for the scissors.

"You should say it," she said.

"Say what?"

"Whatever it is you're not saying. You haven't looked at me since the airlock."

He latched the cabinet and stayed there with his hand on it. "I looked at you in the airlock. That was the problem."

She didn't answer.

"I've flown you down onto things for a long time," he said. "Ice, rock, worse. I never once thought I'd be bringing you back up with somebody's hand in pieces. And I knew. I knew on the shelf you weren't going to walk away from that vent. I still held the ground call. I could have pulled us." He turned around. "So it's not you I'm angry at. Not really."

"It should be."

"Maybe." He came across the bay and stopped close enough that she could see how tired his eyes were. "You think it's real. What's in there."

"I think it's real."

"Then I hope it's real. I hope it's so real they name a building after it." His voice cracked a little at the end and he didn't try to hide it. "I just don't want to fly anyone else down for it."

She reached out and caught the front of his shirt, not to pull him, just to have something to hold. He put his hand over hers. Then he leaned in and kissed her, once, and it was not a careful kiss or a brave one. It tasted of recycled air and too much coffee and two people who had not slept, and it was honest, and when it was over neither of them pretended it hadn't happened.

"That's been waiting a while," she said.

"Years." He rested his forehead against hers for a second. "Bad timing."

"It's always bad timing out here."

Behind them Priya made a small sound in her sleep and they both looked, and she settled, and Kasimir let go of Sunniva's hand and went to check the strap on Priya's wrist.

The hatch opened again.

Okello came in further this time. He had the slate under one arm, and his lanyard was off his neck and wound around his fingers, the worn steel key turning slowly at the end of it. He looked at Kasimir, and at Sunniva, and if he had seen anything he chose not to say it.

"Her numbers hold," he said. "I ran them twice. They hold the way a bridge holds with half its cables. It's survivable. It's not anything I'd ever have signed for at Taldor."

"Then we take the tanker."

"That's what I'd do." He unwound the lanyard. "I've been commanding ships a long time, Sunniva. I've never once handed this to someone else. I don't think anybody should. But I keep thinking that the person who has to live with this choice for the rest of her life ought to be the one who makes it, and it isn't me. She already made hers. In the vent." He nodded toward Priya without looking at her. "Now it's you."

"Okello, that's not fair."

"No." He held the key out. "Tomorrow you arm the burn. Whichever burn. You tell me which way we're pointed, and I'll fly it, and I won't second-guess you to anyone. Not to Kasimir. Not to her. Not to the people at home."

She didn't move. He waited. Kasimir had gone very still by the bunk.

Finally she opened her hand, and Okello laid the key across it and folded her fingers closed over the steel, and let go.

It was colder than she'd expected, and heavier, and the edges where the shipyard had stamped it were worn smooth from years of his thumb.

The Burn Console

The cracked sleeve came out of the cold locker in two pieces, and Sunniva caught the second one with the tongs before it could drift off toward the air return. The quartz stayed in the first half, held by a crust of its own frost. Under the bench light the vial was a thumb of clear glass gone milky at the core, and along the titanium, where the fissure had bitten it on the rim, a hairline ran pale and bright.

"Don't breathe on it," Priya said from the hatch.

She was supposed to be in the medbay. She had hooked her left foot under the rail and her right hand was a white mitten of dressing strapped across her chest, and her face had the grey, scrubbed look of someone who had slept badly and refused anything that would have helped. Kasimir came in behind her and didn't argue, which meant he had already argued and lost.

"I'm not breathing on it." Sunniva set the vial into the bench's little vacuum chamber and sealed the lid. "If the quartz is cracked too, it's been sitting in our air since the rim. Anything it says is ours."

"So check it."

"That's what I'm doing."

The pump hummed through the bench, a vibration more than a sound, and the gauge settled low and lay there. Sunniva watched it. A crack in fused quartz would show as a slow creep upward while the frost inside found its way out as vapor. She had seen that happen once, on a training sample, and remembered the needle climbing so gently she had told herself for a full minute that she was imagining it.

Okello drifted in last. He had shaved. He took the handhold opposite her and folded his arms and said nothing, and she was grateful and also wished he would say something, so she could have something to push against.

The needle didn't move.

"Longer," Priya said.

"I know."

They gave it longer. Kasimir checked the strap on Priya's wrist without asking and she let him. The galley fans cycled somewhere aft. Sunniva became aware of the burn key in the thigh pocket of her coverall, a hard bar against her leg that she had slept on, or tried to.

"It's holding," Okello said at last.

"The quartz is holding. The sleeve isn't." Sunniva vented the chamber and lifted the vial out. "I can't put it in the instrument like this. The clamp needs the sleeve to seat."

Priya reached into the pocket at her hip with her left hand and came out with something wrapped in lint-free cloth. She held it out without a word. Sunniva unwrapped it. A titanium sleeve, new, the bore polished, the outside faceted and uneven where a careful hand would have turned it smooth.

"When did you make this?"

"Last night. Left-handed." Priya's mouth went crooked. "It's ugly. It'll seat."

Kasimir looked at the ceiling. "I gave you something to sleep."

"You gave me something to put in my cheek and spit out when you left."

Sunniva turned the sleeve over in her fingers. There was a burr inside the lip, small, the kind Priya never would have left. She thought of Priya bent over the lathe in the workshop at the end of the ring with one good hand and the other one throbbing against her chest, and she couldn't find anything to say that would be the right size.

"Thank you" was what came out.

"Seat it before I change my mind about being nice to you."

The quartz slid home with a little resistance at the burr and then went the rest of the way. Sunniva logged it, sleeve swapped, quartz sealed, chain of custody unbroken, and then clamped the vial into the inlet of the chromatograph.

This was the part that mattered. The polarimeter had told them twice, from two plumes, that the frost turned light one way and only one way. But a polarimeter could be fooled. A stressed window, a bad heater, a film on the optics. She had said all of that herself on the second day, out loud, as a sober reviewer should, and she had been right to. The chromatograph didn't care about light. It pushed the sample through a column lined with a coating that was itself one-handed, so that mirror-image molecules met it like a left glove meeting a left hand or a right one, and came out the far end at different times. Two peaks meant both hands, meant chemistry, meant Mirrin was cold and dead and interesting in the ordinary way. One peak meant something had been choosing.

She warmed the inlet. A breath of frost sublimed off the inside of the quartz and went into the column as gas, and the trace on the screen began its slow flat walk across.

"How long?" Okello asked.

"A while."

"Ballpark."

"Long enough that you could go and check the tanker solution one more time and come back."

"I've checked it." He didn't move.

The trace walked. Kasimir came around the bench and stood at her shoulder, close enough that she could feel the warmth of him through the sleeve of her coverall, and didn't touch her. Yesterday he would have stood a little further off. Neither of them mentioned it.

The first peak rose out of the baseline and she felt her whole body tighten. It climbed, crested, fell away. She made herself look at where the twin would be, where the mirror molecule would arrive a little later if it were there at all. She had run standards on this column on the outbound cruise. She knew exactly where to look.

The line went on, flat.

"Is that it?" Priya said. "Sunniva. Is that it?"

"Wait."

It stayed flat. It stayed flat past where the second peak should have come, and past where a lazy, smeared one might have come on a bad day, and on into the noise floor where nothing lived but the instrument's own small tremors. Sunniva put the standard's trace over it, the old run with its two neat matched peaks, and there they were side by side on the screen: one pair, and one alone.

Nobody said anything for a while.

Okello leaned in and looked for himself. He looked for a long time. Then he straightened and wiped his palm on his thigh, a thing she had never seen him do.

"That's a different instrument," he said.

"A different principle, a different plume region from the drones." Her voice was coming out too quiet. "Different vial."

"It could still be wrong."

"It could. Not the same way twice."

He nodded slowly. He didn't smile. "All right," he said. "All right."

The burn console sat on the flight deck in its own small recess, a slab of panel with the drive status down one side and the arming slot in the middle, a narrow throat of black steel worn grey at the edges. Both solutions were loaded on the screen above it. The tanker burn sat in green, short and fat and safe, its window still open. The long one sat beside it, a looping thread out and around Aurelle and back, the margins drawn in a yellow that Okello had not let anyone change to green.

Okello took the left seat and strapped in. Kasimir took the medic's jump seat behind him with Priya in front of him, one arm across her ribs to hold her in place, and she let him do that too.

Sunniva floated at the console. She took the key out of her pocket. It had warmed against her leg overnight and now it was the temperature of her, which felt wrong.

"You can still change your mind," Okello said. "I'll fly the tanker burn and I won't say a word."

"I know you won't."

"I'm not saying that to push you."

"I know that too." She looked at the yellow thread. "We'll have to tell Taldor we're not coming to the tanker."

"I've written it. It's queued." He glanced at the comms panel. "By the time they've read it and shouted at us and we've heard them shout, we'll be well around Aurelle. It won't matter what they say."

"It'll matter to you."

He considered that. "Some," he said.

The two drones still in their cradles aft would ride home cold. The vial would ride home on her bench, logged and resleeved and wrapped in its ugly titanium. Priya's hand would ride home in its bandage, and a doctor at Taldor would unwrap it and tell her whatever was true about it, and whatever was true would be because of a crater on a moon nobody had cared about until this week.

Sunniva put the key into the slot. It seated with a click she felt through her fingertips.

Priya unbuckled one strap and pushed forward, and Kasimir let her go, and she reached past Sunniva and laid her right hand on the console beside the slot, the white dressing flat against the panel, the fingers inside it not quite able to close.

"Go on," Priya said. "I want to feel it go."

Sunniva closed her hand around the worn steel and turned it.