Tracing the Chill

How much body heat could a man hide before his own blood began to cook him?

Levmir cinched the chest harness of his vacuum rig over his heavy insulated tunic. Standing on the narrow service platform below Mash Vat Seven, he checked the seals on his faceplate and pressurized the recycled scrubber pack. He had three hours before the bypass loop's thermal reserve saturated and the temperature in Vat Seven climbed past forty-two degrees, sterilizing three tons of yeast into sour mush. To fix the primary radiator, he had to reach the station's unpressurized upper spine, ninety meters straight up through the maintenance throat.

The Cooperative had sealed the upper shafts twenty years ago, declaring them structural dead zones. To enforce that decree, they relied on automated hull-sweepers—blind, relentless crawler drones programmed to vaporize any unauthorized thermal anomaly venting into the station's dark superstructure.

Levmir clipped a pair of serrated pipe clamps to his tool belt. For propulsion, he refused to use a standard hydrazine pack; hydrazine exhaust left a blazing infrared plume that the sweepers would register from half a kilometer away. Instead, he strapped a modified steel canister of cold carbon-dioxide gas to his hip, scavenged from the brewery’s carbonation line. A rubberized hand nozzle gave him three short bursts of reaction mass. If he misjudged his drift in the dark, he would simply bounce against the conduit ribs until he broke a limb or his suit ran out of oxygen.

"Station safety assumes only dead men or scavengers go up the spine," Levmir muttered into his helmet microphone, listening to the flat, muffled rattle of his own breath. "Dead men don't make mistakes with their delta-v."

He cracked the manual dog-latches on the vertical hatch marked Sector 4-Upper.

Air hissed into the throat as the pressure equalized, venting a thin cloud of crystallized moisture that vanished into the void above. Levmir grabbed the ladder rungs welded to the shaft wall and pulled himself upward, kicking gently away from the platform.

Gravity stripped away within six meters. The rotational pull of Zhelezkova was weak at the rim, but at the hub, along the central axis of the radiator conduits, it vanished entirely. Weight ceased to exist. Only inertia and mass mattered now.

Levmir pulled himself hand over hand through the narrow, unlit shaft. His work-lamp cast a sharp, hard beam across walls coated in frozen lubricant and flaking zinc primer. Dead glycol lines ran parallel to his path like severed arteries, black and brittle under forty years of thermal cycling. Every grip required precision; too much force on a corroded bracket would shear the bolt and send him spinning into the central void.

Forty meters up, the vibration started.

It was not a sound carried through air, but a rhythmic, metallic pulse through the steel rung in his left glove. Thump. Whir. Thump.

Levmir froze. He killed his work-lamp instantly.

Total darkness flooded the conduit. Through the thick soles of his magnetic boots, the pulse grew heavier. Thirty meters ahead, a faint red beam cut through the gloom, sweeping the circular cross-section of the shaft in a slow, clockwise rotation.

An autonomous hull-sweeper drone.

The machine crawled along a central guide rail, its multi-jointed steel legs gripping the pipe casing with hydraulic force. At its core, an infrared radiometer spun continuously, searching for any heat source above fifty Kelvin against the background chill of space. Levmir’s suit, even with passive insulation, leaked forty watts of metabolic heat through the faceplate and shoulder seals. At twenty meters, the drone’s sensors would lock onto him and deploy its high-frequency cutting torch to burn the slag away.

Levmir did not reach for his cold-gas thruster. A puff of room-temperature carbon dioxide would light up the drone’s sensor array like a flare.

Instead, he reached for the brass valve on his chest harness.

Connected to his suit’s liquid cooling loop was a rectangular aluminum box packed with four kilograms of solid industrial paraffin wax. The wax sat at minus twenty degrees Celsius. By turning the valve, Levmir diverted the entire fluid output of his suit directly into the heat sink. The paraffin began to absorb his body heat, melting internally without changing its external temperature by more than a fraction of a degree.

His faceplate grew warm as the interior circulation dropped, sweat stinging the corners of his eyes.

He kicked softly with his right boot, using purely mechanical momentum to drift sideways into the recess between two beryllium-copper expansion flanges. The heavy metal flanges acted as an unheated baffle, reflecting the drone’s infrared sweep away from his tucked limbs. He reached out with gloved fingers and gripped the flange's cold lip, halting his drift with centimeters to spare.

The sweeper crawled past his alcove.

Its heavy steel chassis passed six feet above Levmir's visor. The drone’s red optical scanner flicked across the copper flange, registered nothing beyond the ambient chill of the metal, and continued its methodical crawl down the shaft toward the lower hub.

Levmir waited until the rhythmic vibration faded from the conduit wall. He switched his suit cooling back to its standard cycle, exhaling a long, ragged breath against the glass.

"Two kilograms of wax spent," he whispered, wiping sweat from his brow against the helmet’s internal foam strip. "That leaves one more encounter before I cook in my own skin."

He engaged the magnetic soles of his boots and continued his ascent.

Fifty meters higher, the maintenance conduit ended abruptly at a massive bulkhead collar.

Levmir mounted the final staging ring and clicked his tether onto a structural rib. Before him sat the primary access port to the external radiator throat—an oval steel hatch two meters across, marked with faded Cyrillic stencils from the station’s construction era.

This was where the ultrasound probe had detected the dense organic obstruction. If he could open the hatch, he could clear the throat and restore full glycol circulation to the brewery.

Levmir unclipped his pry bar and reached for the central locking wheel.

His gloved fingers touched the rim, and his breath caught in his throat.

The locking wheel was intact, but it was immobile. Around the entire circumference of the oval hatch, filling the mechanical gap between the door and the structural frame, ran a continuous, jagged bead of heavy plasma weld.

Someone had not sealed this hatch against pressure loss. Someone had brought an industrial construction rig up into this restricted shaft, decades ago, and permanently welded the radiator hatch shut from the shaft side.

Levmir scraped his glove across the hardened metal slag. The weld was weathered, scarred by thermal cycling, but unbroken.

The station’s primary heat vent had not clogged by accident. It had been buried.