Descent Through Cold Smoke

How long before the overseers tracked eighty kilowatts of redirected heat back to the body in the pipe? Levmir shoved the stamped bronze token into the reinforced canvas pocket of his tool vest, zippered the flap shut, and pulled the slide-hammer back into his belt harness. The red strobe of the emergency beacon pulsed across the basalt ribs of the radiator plenum every three seconds, painting the frost on his visor the color of arterial blood. Mash Vat Seven was safe downstream, fed by boiling glycol, but every console in the overseer tower was now screaming with the location of the breach.

The synthesized alert droned through his suit transceiver: Unscheduled thermal surge detected in Year 12 manifold. Bulkhead containment compromised. Sector 4 security units, dispatch immediately.

A metallic scrape echoed down the central maintenance spine forty meters ahead. Levmir killed his suit floodlight, leaving only the dim amber readout of his chest pack. His dosimeter showed forty-seven millisieverts per hour. Radiation from the unshielded core was chewing through his suit lining, but a sweep squad with kinetic carbines would end him far quicker than gamma rays.

He kicked off the basalt wall, drifting along the primary conduit guide wire in dead zero-G. His right hand kept contact with the braided steel line, thumb resting on his tether brake. At the intersection of the primary plenum and the vertical access riser, a white pinprick of light flickered.

A Type-4 autonomous scout drone drifted into the junction.

The machine hung on four cold-gas micro-thrusters, its twin optical lenses rotating in smooth sixty-degree arcs. Beneath its sensor pod, an infrared tracking bulb glowed dull purple. The drone was hunting for thermal anomalies. Levmir pressed his spine flat against the unheated basalt frame of an auxiliary heat exchanger. His suit cooling loop, repaired fifty minutes earlier with Olenka's fluoropolymer hose, held nominal at 6.8 bar and twenty degrees Celsius. In an unheated conduit sitting at minus forty, a twenty-degree pressure suit shone like a flare on an infrared raster.

The drone's sensor bulb tilted toward his alcove. A faint click carried through the metal frame as its tracking servo locked on the thermal bloom of his torso.

Levmir looked up at the pipe cluster bolted directly above his helmet.

Running parallel to the main glycol line was an abandoned 100-millimeter bypass loop, marked with the flaking yellow paint of the founding era. The line still held stagnant Freon-14 from the station's original refrigeration circuits, pressurized to five bar behind a mechanical spring baffle and an emergency burst disc. The disc was brittle with fifty years of thermal cycling.

Under five bar of pressure, Freon-14 vented into a sub-atmospheric void would flash-boil into an aerosol fog of micro-droplets chilled to minus eighty degrees. A plume that cold would blind thermal optics across the entire corridor and drop local visibility to zero.

Levmir swung his legs around the basalt mounting bracket, wedging his magnetic boots into the structural flange to anchor his mass against recoil. He unclipped the pneumatic slide-hammer from his harness, slotted the hardened beryllium-copper chisel into the chuck, and lined the bit against the brass shear pin of the emergency vent baffle.

The scout drone's micro-thrusters hissed. It advanced three meters into the alcove, optical lenses focusing to acquire a telemetry lock for Kordov's pursuit team.

Levmir squeezed the slide-hammer's pneumatic trigger.

The piston slammed home with a sharp industrial crack. The brass shear pin snapped clean. The burst disc buckled outward, tearing along its scored relief lines with a shrieking metallic pop.

Five bar of trapped refrigerant tore out of the cracked nozzle in a violent, expanding geyser.

The liquid hit the low-pressure plenum and flash-boiled into a roaring wall of white vapor. Dense clouds of sub-zero fluorocarbon aerosol swept through the junction, dropping the corridor temperature fifty degrees in two seconds. The thermal raster on the drone's optics washed out into solid static. Chilled droplets frosted the drone's camera apertures, while the expansion blast struck the machine's lightweight chassis, spinning it end over end into the opposite basalt bulkhead.

Overseer doctrine programmed security drones for decompression breaches and armed saboteurs, leaving their sensor arrays helpless against five bar of industrial plumbing failure.

Levmir did not waste the momentum. As the expanding vapor plume billowed outward, the reactive pressure wave caught his broad shoulders. He tucked his arms against his chest, disengaged his magnetic boots, and let the force of the refrigerant blowout launch him straight into the mouth of the vertical maintenance riser.

The sub-zero cloud swirled around his helmet. Frost crusted across his outer faceplate, crackling as his internal heating elements fought off the cold shock. His suit cooling loop shuddered under the external temperature drop, pressure dipping to 6.2 bar before the internal thermostat throttled the flow.

Levmir reached out with a heavy gauntlet, snagging the vertical descent rail as he shot down the shaft. The friction brake on his glove screamed, throwing sparks into the dark before his descent slowed to three meters per second. Behind him, the roar of venting Freon faded into the metallic reverberation of the plenum alarms.

He descended ninety meters through the zero-G spine, hand over hand, using the guide rail to guide his momentum. Every ten meters, a yellow marker ring flashed past in the dim red emergency light: Level 2, Level 3, Level 4. The clicking of his suit dosimeter slowed, dropping from forty-seven millisieverts to nine as the thick rock of the middle strata shielded him from the founding core.

At the base of the riser, the narrow maintenance spine opened into the transition airlock that connected the restricted upper decks to the commercial fermentation halls of Sector 4.

Levmir caught the rim of the hatch frame with both boots, absorbing his kinetic energy against the basalt deck. He reached for the heavy cast-iron dog-wheel of the transition door. If he could throw the mechanical dogs, slip through, and seal the pressure door behind him, the thick titanium-lead hatch would block the drone's acoustic sensors and buy him time to reach Mash Vat Seven.

He grabbed the spokes of the wheel and wrenched counter-clockwise with his full weight to disengage the dogs.

The wheel did not move.

Levmir struck the rim with the base of his pneumatic spanner, trying to shock the mechanical dogs loose. The linkage remained dead.

Above the hatch wheel, a rectangular status panel blinked beneath a thick polycarbonate shield. Four high-voltage electromagnets hummed deep inside the steel doorframe, vibrating through Levmir's thick work gloves.

A steady red legend burned across the display: EMERGENCY SEAL ACTIVE. SECTOR 4 INTERFACE MAG-LOCKED BY OVERSEER COMMAND.

Levmir stepped back on the zero-G rail, his breath fogging the inner glass of his helmet. Behind him, up the ninety-meter vertical shaft, the faint stutter of approaching cold-gas thrusters echoed against the frozen pipework.