The Mailbox, 2D: CO2 Scrubber Adapter Crisis

A cramped spacecraft cabin, three crew instead of the two it was sized for, and a CO2 scrubber canister racing to saturation before the flight is over — this 2D cutaway simulator models the exact mass-balance problem behind the most famous improvised fix in spaceflight life support. Cabin CO2 partial pressure climbs from crew metabolic output against a chemical bed whose absorption rate falls as it saturates; the only spare canisters aboard fit a different socket entirely. Build the adapter before the readout crosses the danger line, and watch a mismatched hardware interface — not a lack of supplies — turn out to be the real risk.