Liwei was halfway across the big central panes of the crop module when a soft beep sounded in his ear and a warning light flashed across his helmet display, crimson dawn blurring out the endless backdrop of stars.

Flat against the impregnable glass with his guide lines radiating from his suit, an outlandish and fragile spider traversing a bubble suspended in nothingness, he let training take over, freezing all movement. Blinked his suit gauges into the hud. His oxygen supply was low, and falling fast. Too fast to complete the walk as planned.

Somehow he must have sustained a puncture that his suit’s SmartSkin sensors had failed to pick up. A minor incident, easily stitched up with a sealant gun or a tube of hardcaulk, if only he’d detected it inside. Out here, with nothing but the thin scrim of atmosphere the suit contained, it could spell serious trouble. A death sentence, if he allowed his mind to drift that way and panic to take over. So he didn’t.

Instead, his free arm sought the tension of the tether holding him clipped to the agrifuge struts. Found nothing but slack. Liwei turned to the side, saw the other end of the line drifting away from the clip, unsecured. Tiny as the leak had to be, it was spinning him head over heels, propelling him into a slow, irretrievable tumble away from the glass, into the vacuum.

Letting himself roll into the spin always felt like suicide in training, but Liwei was an experienced spacewalker, had learned to override planetside-evolved instincts to preserve himself in space, where different rules applied. Death beckoned from the void, cold stars scintillating across an unimaginable gulf. Below him, then above him, the lights of the agrifuge shimmered, the artificial fields underlit by ultraviolet tubes, a swaying, rolling sea of green.

Liwei’s fingers found the safer controls, thumbed off the catches. He adjusted for the jet from the ruptured tank, which was pushing him sideways as well as away from the glass. One chance was all he would get. He waited for the spokes to roll into his viewfinder, for the hub to align between them, and fired the thrusters.

The airlock seemed tiny at this distance, his positioning graphics skewing wildly like they always did before the guiding program locked in. Liwei kept his breathing steady, his eyes on the vector: inside his gloves, his palms were steady and dry. If he missed the airlock, or overshot the station’s central module, he might have enough fuel to decelerate and make another pass. Xiao, the chief engineer, might have just enough time to pull on a suit and attempt to retrieve him. A trapeze act, like the ones he’d watched in the circus as a child, no less lethal for the absence of gravity. The station’s emergency manuals laid out the steps for a rescue protocol, but to Liwei’s knowledge one had never been attempted before.

All this passed through his head as the central module of Jùb?opén V surged in his visor, fist-sized at first, then growing to immense proportions, its pitted exterior lined with observation ports and extensions and maintenance walkways. He had time to register his angle of approach, the panicked voice jabbering in the suit’s audio feed, before his brain dredged up a warning: he was coming in too fast, the airlock yawning open like a great mouth, intent on swallowing him.

Galvanized beyond fear, Liwei shot his palm thrusters into reverse, sending a silent prayer into the eternal night. It went against his ideological conditioning, would go on his record if he’d spoken it loud enough for the suit to pick up, but he was well past caring. He felt the jolt of deceleration, felt his hands clench on the controls, fingers aching with effort. The horizon tilted, the vast edifice falling toward him slowed down. But the correction had thrown him off vector – a slight miscalculation, yet enough for the airlock door to dip under his feet.

Liwei whipped round and made a grab for a handrail, missed. Slammed into the wall and bounced, sending a burst of unintelligible alerts across his hud. Flailed around for a loose cable, a projection, anything to slow his agonizing slide over the edge of the station.

This was how you died in space, the lessons warned. There were hundreds of ways, but in most cases it started off as a small thing, innocuous at first, leading to another, and then the primate brain kicked in, reflexes acquired in an environment where up and down mattered, and you were truly lost. Blowouts and system failures were anticipated by the designers, with failsafes and multiple redundancies built in to mitigate the risk. A snapped line, or a moment’s inattention, killed with remorseless certainty.

Somehow he arrested his momentum, worked the thrusters with gentle taps, tiny jets nudging him backward, until his gloved fist closed around the airlock rail, pulled him inside.

Liwei lay on the floor, fighting the urge to throw up, as air pressure thrummed into the lock. He tore off his helmet, but could not get his shaking legs to hold him up, even in microgravity. The numbers on his suit gauges danced wildly in his vision. His oxygen gauge had maybe five minutes left. It was just his imagination, but he thought he could feel the sucking of the vacuum just outside the door, seeking a way in. Determined to get him next time.