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VESSEL: R/V Meridian POSITION: 11.3892°N, 142.5917°E SEA STATE: 2 (slight) DEPTH TO HABITAT: 8,012m

DAY 1 OF 365

364 days remaining.

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Static has a texture most people don't notice.

Low-frequency hum from the ship's generator. The faint crackle of ionospheric interference. A rhythmic pulse that's either the signal bouncing off a thermocline or my own blood pressure registering through the headset's foam seal.

I adjust the gain, center the frequency, and transmit.

"Meridian comms to Hadal-1. Night shift check-in. Call sign Lima-Sierra-Hotel. Requesting status, over."

The Pacific is black through the porthole beside my station. Thirteen hundred hours of training for this. Two years of grant proposals. A PhD in marine acoustics that my mother still doesn't understand.

The speaker crackles.

"Hadal-1 to Meridian." A man's voice. Low. Slightly hoarse, like he hasn't spoken in hours. "Receiving. Status nominal. Over."

I open the monitoring panel. His biometrics populate the screen in clean green columns.

Heart rate: 68 bpm. Respiration: 12/min. Cortisol: baseline. Blood pressure: 116/74. Cabin temperature: 4.1°C.

Everything within parameters. The most isolated human being on the planet, and his body doesn't seem to register it.

"Copy, Hadal-1. Beginning wellness assessment. How are you feeling today?"

I read the question from the laminated card velcroed to the console. There are fourteen standard wellness prompts. I cycle through them across the week, two per night, logging his verbal responses alongside the biometric data for the mission psychologist.

"Fine."

One word. I mark the response on the form. Fine translates to nominal, no significant self-reported distress. I'm not sure it actually translates to anything.

"Any changes in sleep quality since last report?"

"No."

"Appetite?"

"Functional."

His breathing is steady in the headset. Twelve cycles per minute. I can hear the habitat's ventilation system behind him, a low mechanical hum pitched at roughly 120 hertz. The acoustic signature of a pressurized titanium shell surrounded by 800 atmospheres of ocean.

"Environmental report?"

"Ambient pressure stable. Water recycler nominal. CO2 scrubbers running clean. External temperature 1.8 degrees. Bioluminescence off the port viewport." A pause. "Amphipods, I think. Hard to tell."

The longest thing he's said. I write it down.

"Copy. Any equipment concerns?"

"Negative."

Fourteen more minutes of this. Short answers that clip off like he's rationing words. I ask about his research schedule, his equipment logs, his oxygen metrics. He responds in fragments. Nominal. Standard. No issues.

I think about the man at the other end of this signal. Forty-one years old according to the briefing file. Marine geologist. Former professor at Scripps Institution of Oceanography. Volunteered for the mission, which tells me less than it should, because nobody volunteers to live alone at the bottom of the Mariana Trench for a year unless the surface has become uninhabitable to them in some private, irreversible way.

The briefing file had a photograph. I didn't look at it. I'll be his comms officer for twelve months. I don't need to know what he looks like. I need to know what he sounds like.

Right now, he sounds like someone answering questions because the protocol requires it.

"Last item. Anything you'd like to discuss before sign-off?"

"No."

I hover over the transmit button.

There's a question I'm not supposed to ask. Not on the card, not in the protocol. It formed in my throat about twenty minutes ago and I've been holding it behind my teeth like a coin I'm not ready to spend.

What does it sound like down there when there's no one on the line?

I press transmit.

"Copy, Hadal-1. Meridian comms signing off. Good night."

"Good night."

The line cuts. The static returns, briefly, then fades as I close the channel. The silence of the comms station settles in around me like water filling a space that just emptied.

I log the call. Forty-two minutes. Standard duration. All responses within normal parameters.

I remove the headset. The foam has left impressions behind my ears. I look at the depth reading on the sonar display.

8,012 meters.

I've worked with acoustic data my entire career. I can identify whale species by frequency. I can tell you the density of a sediment layer by how sound bends through it. I once diagnosed a faulty research buoy from three hundred miles away by listening to its ping interval drift.

I have never heard a voice from that far away.

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HADAL-1 CREW VITALS, 0007 UTC

Heart Rate: 66 bpm Respiration: 11/min Cortisol: baseline Blood Pressure: 114/72 Cabin Temp: 4.1°C Depth: 8,012m

I close the monitoring panel.

All nominal.

I look at the depth reading one more time before I leave the station.

8,012 meters below me, a man just said good night to the only person who will speak to him for the next three hundred and sixty-four days.

I walk back to my cabin. The ship rolls gently beneath my feet. The engines hum at 85 hertz. The fluorescent lights in the corridor buzz at 60.

I know the frequency of every sound on this vessel.

His voice was somewhere around 110 hertz. A low baritone, compressed by the acoustic modem and stretched slightly by the transmission delay.

I should not have noticed that.