No Instrumental Explanation

by Tim Collyer

BIO-CANDIDATE CLASS A appears on Priya Mehta’s screen at 11:47 p.m., in yellow, which is almost rude.

Yellow is for marginal sodium lines, thermal drift warnings, bad flat-field corrections. Yellow is for things that will waste half an hour and then apologise by disappearing. This one sits inside the retrieval log with three annotations she has only seen in simulations.

O₂ confirmed.

CH₄ confirmed.

Joint detection exceeds 5.3 sigma.

The corridor outside her office is empty apart from the strip light near the women’s toilets, which flickers, steadies, flickers again. Facilities had replied that the matter had been “logged”, a word that meant nothing had happened, but in a documented way.

Priya does not touch the phone.

She opens the raw transit photometry. The planet is not much to look at in the files: a sequence of dips, error bars, timestamps, a star made into numbers. A super-Earth crosses the face of a K-type star and removes less light than a moth passing a porch bulb.

She reruns the limb-darkening model.

The oxygen band comes back.

She tightens the Bayesian priors until she would have called it ungenerous.

The methane remains.

She checks the detector persistence logs from the bright target observed before transit. Clean. She checks for cosmic ray hits. Nothing close. She pulls the attitude control record and scans the observation window for thruster firings, jitter, smear. Nothing. The telescope held its stare better than most people hold a conversation.

In the kitchenette, she fills the kettle. Her mug says ASK ME ABOUT HABITABLE ZONES, a present from Anika, who had found it hilarious at thirteen and faintly embarrassing by fourteen. The tea bag darkens the water. She forgets the milk.

Back at her desk, she checks the stellar activity record: chromospheric noise, flare probability, contamination from starspots crossing the transit chord. The star has been quiet all week. Annoyingly quiet. Professionally quiet.

She still expects persistence, a detector afterimage wearing a false beard. Her own false-positive suite should find it and give her back Tuesday: the one she wrote after a conference in Munich where three men had tried to explain her own threshold paper to her beside a plate of sweating cheese. Abiotic oxygen from water loss. Volcanic methane. Photochemical tricks in a thin atmosphere. One by one, the models fail to make the two lines sit together.

She tries the old retrieval code, the one she distrusts because it once mistook water vapour for a calibration error and sulked when corrected.

Oxygen.

Methane.

At 11:59 p.m., she writes in the observation log:

Retrieval confirmed. No instrumental explanation identified. Atmospheric biosignature at CLASS A threshold.

The sentence looks plain enough. A lab note. Something a person might type before asking Facilities about the strip light again.

James is in Lagos. He will be asleep, or nearly asleep, or awake and reading something he has no business reading before bed. She should call him. His name is first on the paper; hers is second, by insistence and alleged indifference.

The preprint will upload at six. Coordinated release. Six authors. Institutional protocol. Press lock until confirmation committee review, though the abstract will last about forty minutes before someone starts shouting online.

She puts on her coat.

In the lift, she watches the floor numbers descend. The tea sits on her desk, too strong now, cooling beside the star.

***

The supermarket is eight minutes away and badly lit in the honest way of places that sell bananas at midnight.

Priya takes a basket. The handle is sticky. A refrigerated case hums over cut fruit sealed in plastic tubs, melon sweating against the lids. A cleaner guides a floor machine around the produce section with the slow concentration of a man docking a spacecraft on a budget.

She has no list.

She puts in a tin of Campbell’s tomato soup, saltines, Greek yoghurt with honey, a two-kilo bag of basmati rice, dishwasher tablets, and a single lime. The rice is absurd. She has rice at home in a clear tub with a blue lid. She bought more last week. She remembers measuring some out on Sunday while talking to her mother about whether foxgloves poison dogs. Yes, her mother had said. Probably. Don’t let anyone eat them. As if Priya kept spare dogs.

In the cereal aisle, she stops.

Honey Nut Cheerios. Raisin Bran. Frosted Mini-Wheats. A box of Lucky Charms with a rainbow marshmallow floating above the bowl. On the bottom shelf, an own-brand cereal called Moon Rings shows a smiling planet with pink cheeks. Beside it, Cocoa Comets. A yellow sun winks from the corner as if it has been let in on the joke.

She picks up Moon Rings and reads the panel.

Sugars: 13g.

Iron: 45%.

Riboflavin: 20%.

Anika used to eat cereal from the box while revising, one hand in, one eye on equations.

Nearby, a stock boy is pulling cereal boxes forward so their faces meet the edge of the shelf. He is perhaps nineteen. He takes three boxes of Cheerios from the back and makes a neat wall of them.

Priya looks at him for long enough that she worries he will look back. He doesn’t.

She could say, “Something alive is out there.” The sentence is ridiculous.

The boy nudges one box level with two fingers.

She puts Moon Rings back.

At the self-checkout, the machine tells her to place the item in the bagging area. She places the soup there. It tells her again. ERROR flashes in the corner. For one stupid second, the word reaches past the supermarket.

“It’s there,” she says.

The attendant, a woman in a padded gilet, comes over with a key card. “They get lonely,” she says, and clears the error.

Priya pays. The receipt prints and prints, far too long for six items and a lime. She folds it twice and puts it in her coat pocket.

Outside the automatic doors, the cold touches her face. The night smells of tarmac, exhaust, and the wet cardboard stacked by the bins.

***

Her mother answers on the third ring.

“Priya?”

“Hi, Ma.”

A small rustle. Sheets, maybe. A lamp switch. “What time is it?”

“Late.”

“So, naturally, you are calling to ask about compost.”

Priya closes her eyes. She is sitting in the car with both hands on the steering wheel. The supermarket sign glows red in the rear-view mirror.

“No,” she says. “How’s the garden?”

“Full of things I did not invite. The foxglove is back.”

“You didn’t plant it?”

“I keep telling you. It arrived like a relative. Tall, poisonous, confident.”

Priya almost laughs, but it catches wrong in her chest. “Don’t touch it without gloves.”

“I am seventy-four, not decorative.” Her mother yawns. “Mrs Alvarez’s dog got through the fence again. Dug under it this time. Came in with soil all over his nose and looked offended when I returned him.”

“Which dog?”

“The stupid one.”

“They have three.”

“Yes.”

Priya looks through the windscreen. A taxi passes at the far edge of the car park, slowing for the light, then moving on.

“How is Anika?” her mother asks.

“Good. She got ninety-two on the maths test.”

“She told me ninety-four.”

“Did she?”

“She always improves marks for grandmothers. It is a kindness.”

Priya presses her thumb into the seam of the steering wheel. The material has split slightly. “She’s doing well.”

“And you?”

“I’m fine.”

“That was quick.”

“I am fine.”

Her mother says nothing for a moment. Priya can hear a faint click, maybe the old bedside clock, maybe her mother’s bracelet against the phone.

“Are you eating?”

“I bought rice.”

“At one in the morning?”

“And soup.”

“Very glamorous.”

“I thought so.”

Another pause. This one has weight, but her mother does not push it straight away. She has never been a straight-pushing woman. She comes at things from the side, like a cat pretending not to want your chair.

“Something happened at the telescope place,” she says.

Priya looks at the receipt sticking from her pocket. “It’s good.”

“How good?”

The question sits there.

Priya could say: oxygen and methane. She could say: the ratios hold. She could say: all the little trapdoors we built into the system are shut.

Instead she says, “I just wanted to hear your voice.”

Her mother breathes out. “It’s nice to hear yours.”

“I woke you.”

“Yes. I will survive this great hardship.”

“Go back to sleep.”

“You also. Or do your scientists not sleep any more?”

“Some do.”

“The careless ones.”

Priya smiles. It feels odd on her face.

After the call ends, she keeps the phone in her lap. The car park lights make orange circles on the tarmac. There is a crushed paper cup near the trolley bay. It moves once in the wind, then stops.

***

At 2:50 a.m., she takes out the receipt and turns it over.

The back is slightly waxy. Her pen hesitates before the ink catches.

RA 217.8942

Dec -18.4431

ATLAS-771c / obs ID ATLAS-L2-771402

Confirmed retrieval 23:59 EST

She writes carefully, as if poor handwriting could alter the sky.

The information is on her laptop, in the institute archive, in the telescope downlink record, in two mirrored servers, in the automated release package, and in James’s inbox queue waiting for dawn. Writing it on a supermarket receipt does nothing.

She folds the paper along the line between dishwasher tablets and lime.

The light left that planet twelve years ago. It travelled while she was still in Baltimore arguing about detection thresholds in a room with too much air-conditioning and a postdoc from Munich who kept saying “suggestive” when he meant “weak”. It travelled while Anika was four and refused to wear socks that had seams. While Priya and Daniel were still married, then not. While the telescope was still panels, drawings, budget fights, a test mirror in a clean room. While she wrote the paper that said what would count and what would not.

The planet had already done it.

Or the atmosphere had. Or whatever lives there had. No, not whatever. She will not decorate it. Oxygen. Methane. Production rates. Disequilibrium that refuses to die.

She wipes under one eye with the heel of her hand and is surprised to find it wet. Then the other. No sobbing. No noise. Her body has opened a tap somewhere without informing her.

A van turns into the far side of the car park, idles for a minute, then leaves. Delivery, wrong entrance, lost driver. Priya watches its white flank pass behind the empty trolley corral.

For six hours, perhaps less now, she is the only person who knows.

James is asleep, the upload is pending, and she has not made the call.

She takes the receipt out again and touches the numbers with one finger.

On the printed side, beneath the soup and the rice, the supermarket has given her a coupon for thirty cents off kitchen roll.

***

By 3:55 a.m., the car park has emptied properly.

Priya gets out and locks the car, though there is nothing in it worth stealing except the laptop and the folded receipt. The cold enters her sleeves. She puts both hands in her pockets. Her right hand closes around the receipt.

Above the supermarket, the sky is not black. It is the muddy amber of a city refusing to switch itself off. Near the horizon, a plane blinks its way east. Two stars show through the wash, then a third when she stops trying.

She knows where to look.

Right ascension, declination, the host star’s catalogue numbers, its mass, its temperature, the timing of each transit, the amount of starlight filtered through a ring of air twelve years gone. She knows the patch of sky as a coordinate, not a sight.

She does not look there.

There would be nothing to see. The star would be one ordinary point. The planet would remain absent. Its air would remain arithmetic.

She looks instead at the trolley bay. At the paper cup. At gum flattened into the tarmac. At the red smear of the supermarket sign reflected in a puddle near her left shoe.

People have stood in car parks at four in the morning for arguments, cigarettes, shift changes, bad news, worse dates, babies who will not sleep, dogs being sick in the back seat, the last quiet minute before going home. She has stood in them for some of those reasons herself.

Never this.

The cold starts to hurt her knuckles. She lets it.

“They should know,” she says.

Her voice is small and ordinary in the open air. No one hears it.

They will.

She returns the basket she forgot to return, pushing it into the stack outside the doors. The line of baskets shifts with a plastic clack, accepting it.

Then she gets in the car and drives back.

***

At 5:58 a.m., the institute is no longer asleep.

A postdoc in the atrium is eating crisps from a vending-machine packet while staring at a terminal. Security is making rounds on the third floor; Priya hears the clipped murmur of his radio through the stairwell door. Someone has made burnt coffee somewhere and abandoned responsibility for it.

The strip light outside her office still flickers.

Her tea is on the desk where she left it, dark and cold, a skin forming at the edge. She opens the laptop. The release interface shows the paper in queue.

1 min 47 sec.

She checks the title.

Robust Oxygen-Methane Disequilibrium in the Atmosphere of ATLAS-771c, a Temperate Super-Earth at 3.7 pc.

She checks the author list. James first. Hers second. Everyone present. No one misspelled. The abstract is clean. The figures are clean. The retrieval table sits on page four, modest and fatal.

Beside the countdown sits the blue HOLD RELEASE button, put there for suspected faults and author panic, though the manual only admits the first. Priya rests the cursor over it.

No instrumental explanation identified.

She moves the cursor away.

1 min 12 sec.

She thinks of calling James and imagines his phone lighting on a table in Lagos, his hand reaching through dark, his voice rough with sleep. Priya, what did you break?

She does not call.

At 6:00 a.m., the counter reaches zero while she is in the kitchen rinsing her mug.

The coffee machine coughs into a paper cup. She watches the dark stream hit the bottom and spread. Down the hall, in her office, the server assigns its timestamp. A DOI attaches itself. Somewhere in the east of the country, a person who monitors the astrobiology feed will soon sit up straighter. Then the phone will ring. Then another. Then James will wake and see.

Priya carries the coffee back to her office and sets it beside the cold tea.

She turns on the small radio on the windowsill. It takes a second to find the station, gives a little burst of static, then settles.

The radio plays something.

She doesn’t hear it.