Lena was fifteen years old and had too many questions for orbit. Aboard the School Station Copernicus she was learning physics, code and listening. In the evening, she would plug an old receiver into the railing and catch a strange echo. That day the echo returned five times, growing, as if the station was answering itself. The screen flashed the time stamp of tomorrow, 07:14 deck time to be exact. There was a rumour in the chat rooms about a ghost in the system, which no one believed. Kamil, the best of scripts, raised an eyebrow when she showed him the transcript. Maja brought in the school's Swist drone, plugged in the battery and set up tracking. The signal disappeared into an empty service band, where students rarely looked. The guardian on duty was circling Deck A, so they escaped through a gravity-free tunnel. Magnetic socks clicked on the walls and the blue of the Earth trembled beneath them. Lena picked up the receiver and clipped it to the interface of the onboard drone. Her watch jerked on her wrist as the signal bit the band like a blade. Swish extended the detectors and let threads of light fly through the air like a spider web. He mapped the twists and turns of the corridor until suddenly he stopped at a panel marked catering. Something cool and rhythmic resonated behind the metal, almost like the sound of a canned heart. Kamil scanned the module number and squirmed, seeing a gap invisible in the plans. The timestamp blinked again, now offset by a second, like a sliding needle. There was also a quiet crackling sound behind the panel, reminiscent of capacitors being discharged. A manufacturer's label flashed in the logs, a long-banned company from Shanghai. Maja plugged in the flat key and released the lock, though her fingers trembled a little. The panel sprang open, revealing a narrow module without markings, black and silent as a well. Inside glowed a circular screen on which floated a single word: WELCOME, LENO. A swish beeped as it detected an oxygen leak, and tossed us our emergency masks. The screen flashed with numbers that formed a countdown; nine seconds left. Kamil threw me a look in which fear and curiosity mingled. Lena touched the frame and the screen spat out a diagram of the station with a flashing dot. A door slammed behind me, as if someone from outside had just turned on the lock. A metallic footstep came from the corridor, as if someone was putting their feet up without gravity.