Life-support alley is a narrow throat of labeled pipes. Dr. Amara Okonkwo is already there, one ankle hooked under a rail, a bruise darkening on her forearm from the first tumble. She does not waste a greeting.

“Emergency loop is on,” she says, tapping a panel that still has power from the battery bus. “That means a small fan, a backup tank, and a scrubber the size of a lunchbox. Oxygen is fine. Oxygen is the trick. Carbon dioxide is the leftover you breathe out. The cartridge that grabs it is almost spent, and the main fans are dead. Too much CO2 and your brain gets sleepy and sure of itself.”

You taste a faint sweetness that does not belong. The yellow CO2 number is climbing in patient, ugly steps.

Okonkwo holds up a white lithium-hydroxide cartridge, the chemical brick that locks CO2 away so the air stays thinkable. “I can swap this and keep the emergency loop as our floor. Or you can decide computers matter more than brains. I have opinions. I also have a job.”

The ship rolls. A wrench on a tether taps the wall in a slow, annoying drum. Down the corridor, the breaker wall waits like a piano someone dared you to sit on.

Okonkwo watches your hands, not your face. “Crew first is not a poster. It is chemistry.”