The Severing Wheels

Where in Station Two's blinded vestibule could three pairs of hands reach the overhead intake couplings before the automated nitric purge melted their vulcanized suits into slag? Riosbh pressed her rubberized palms flat against the shuddering concrete floor, her breath scraping raw against the dry intake baffle of her rebreather. The yellow culvert fog drawn in by the storm gate's vacuum was already curdling into an oily, orange aerosol under the ceiling nozzles. A sharp, vinegar bite penetrated the mutton-tallow seal at her neck rings, hot and corrosive on her collarbone. They had perhaps ninety seconds before the main header valves opened and five hundred gallons of industrial oxidizer drowned the chamber.

"Colmhaign," she shouted, the dense, humid air swallowing the tail of her voice. "The ceiling array! It’s not a centralized spray bar. It’s an independent ring main above the secondary bulkhead!"

A beam of pale carbide light slashed through the amber vapor three paces to her left. Colmhaign emerged from the murk, boots planting heavy on the wet decking. He held the two-foot iron decoupling lever gripped tight across his chest, the jagged fracture where he had snapped it from its spring-bracket gleaming silver in the fog. Behind him, Murchadh was on his knees, coughing hard into his facepiece while he fumbled with the spanner roll at his hip.

"Give me a target, Riosbh," Colmhaign said. His voice was stripped of inflection, measured to save oxygen. "I have the lever. Where does the mechanical cutoff sit?"

"Eight paces south of the inner storm door," Riosbh said, rising into a crouch. Her calves burned under the weight of the vulcanized canvas, the stiffness in her left sleeve reminding her of the brittle patch where they had cut away the crystallized fabric over the culvert gorge. "The station blueprints call for two manual decoupling wheels mounted on the cross-truss. One isolates the atmospheric intake from the culvert; the other dumps the nitric line into the exterior ballast sump."

"And if the hydraulic solenoids are already energized?" Murchadh croaked, hauling himself up against an iron conduit. His faceplate was smeared with greasy tallow. "If those lines are charged to forty bar, turning an iron wheel by hand is going to shear the brass teeth off the spindle."

"Then we shear them after the gate closes," Riosbh snapped, pointing her flashlight toward the ceiling.

The beam struck a wall of swirling mist. Overhead, the hiss of pressurized fluid was deepening into a low, hydraulic moan. The station's automated biocontainment computer did not recognize three technicians trying to salvage their lungs; it saw an unverified biological mass breaching the airlock threshold during a peak spore cycle. To the logic board, nitric acid was merely a housekeeping solvent.

Riosbh took the lead, her boots splashing through puddles of caustic drainage that sizzled faintly against the vulcanized rubber soles. Her mind tracked the geometry of the standard Mark-III way-station: eight meters from the outer threshold to the service stanchion, three meters between the vertical conduit banks, and an overhead catwalk that should carry the manual servicing valves for the decontamination loop.

"Stanchion Seven," she called out, her glove striking the cold, fluted iron of a support pillar. "Ladder rungs on the eastern face. Colmhaign, follow me up. Murchadh, watch the floor drain. If the caustic runoff pools over the deck grating before we clear the manifold, it will burn through our boot seams."

"Management spent five hundred thousand credits on automated poisons and six bits on drainage slope," Murchadh muttered, racking his spanner with a wet clink. "Go on. I'm right beneath your heels."

Riosbh hooked her fingers over the first rictus of the iron ladder. The metal was icy and coated in a greasy film of condensed spore sap and acid vapor. She pulled her weight upward, each rung vibrating with the rhythmic thump of the station's distant pumps. At four meters, her helmet bumped against the expanded-metal grating of the upper service catwalk.

The air up here was hotter, thick with the pungent stench of decomposing organics and concentrated nitric mist. Her eyes watered behind the glass port as aerosol droplets found the micro-fissures in her faceplate gasket.

"I have the manifold box," Riosbh said, swinging her leg over the safety rail.

She swept her flashlight along the ceiling truss. Three parallel pipes ran through the steel web: a four-inch seamless steel line, a six-inch insulated return, and a heavily corroded cast-iron main painted with faded yellow biocontainment stripes. Between them sat the decoupling junction—two heavy spoked wheels, six inches in diameter, recessed into an iron housing caked with decades of calcified scale and dried grease.

Colmhaign pulled himself onto the catwalk beside her, the iron lever ringing as he laid it across the grating. "Which one first?"

Riosbh leaned close to the housing, wiping the fogged glass of her helmet with the back of her wrist. The yellow identification stencils had long since peeled away into flakes of rust. Both valve stems disappeared into identical flange boxes bolted to the concrete ceiling.

"Wait," she said, raising a gloved hand.

"The timer horn is at thirty seconds," Colmhaign replied quietly.

"If we close the atmospheric return first, the pressure differential will burst the blast dampers," Riosbh said. Her pulse hammered against her temples, but she forced her fingers to trace the iron castings. Her left hand gripped the leftmost pipe, feeling the deep, cold vibration of rushing liquid. Her right hand moved to the center line.

"Riosbh," Murchadh called from the bottom of the ladder. "The pre-spray nozzles are dripping. The mist is turning red."

"Quiet," she whispered.

She closed her eyes inside the suit, ignoring the flashing amber glare and the stinging vapor at her neck, relying entirely on the tactile memory of the maintenance manuals she had memorized during her lonely rotations on Station One. The pneumatic atmospheric line had smooth, rolled-steel couplings with welded flanges. The chemical purge line was cast iron, with raised reinforcing ribs every four inches to prevent rupture under thermal expansion.

Her fingertips found the sharp, rhythmic ridges beneath a layer of crumbly rust.

"The right wheel," she said, her eyes snapping open. "The ribbed casing. That’s the nitric supply. If we don’t close that gate before the solenoid fires, the acid will bypass the manual lock entirely."

Colmhaign did not hesitate. He grasped the right wheel with both hands, his heavy canvas shoulders bunching as he threw his full body weight into the turn.

The wheel did not move. The cast-iron spokes bit into his vulcanized gloves, the spindle frozen solid in its seat by years of chemical corrosion.

"Seized," Colmhaign grunted through clamped teeth. "The packing gland is fused."

A high-pitched klaxon began to pulse from the ceiling corners—a sharp, mechanical shriek that signaled the final five-second charge of the main deluge pumps. Above their heads, the flexible feeder hoses swelled like engorged veins, the rubber groaning as five hundred pounds of line pressure surged against the closed solenoid valves.