Lunar EVA Walk-Back Limit Simulator

A spacewalking astronaut's suit carries no infinite supply — only a fixed mass of oxygen and a scrubber canister with a fixed carbon-dioxide capacity, both draining in real time against the crew member's own workload. This simulator models both budgets with real physiology and chemistry (the caloric equivalent of oxygen, a respiratory-quotient-derived CO2 production rate, and the stoichiometry of the LiOH scrubbing reaction), then applies NASA's walk-back rule to compute a live, shrinking safe-return radius around the habitat. Watch the astronaut's traveled distance chase that shrinking boundary as the EVA clock runs, tune workload, tank size, canister size and reserve margin to see how each moves the crossing point, and flip on Rover Assist to see the exact technology upgrade — the Lunar Roving Vehicle — that let Apollo 15 through 17 roam kilometers farther than the walk-only missions ever could.