Emergency Reserve Drawdown (2D)

Emergency Scenario

Crew size 4

Rationing level

Time acceleration 1.0 d/s

Reserve Levels

O₂

100%

Water

100%

Power

100%

Mission Clock

Elapsed

0.0 d

Days to critical

Binding resource

O₂

Status

Nominal

How it works

Each reserve depletes linearly under constant per-person daily consumption, scaled by a rationing factor the crew imposes to stretch the supply:

R(t) = R0 - k · N · f · t
days-to-empty = R0 / (k · N · f)

where R0 is the starting reserve (kg or kWh), k is the nominal per-astronaut daily consumption rate, N is crew size, f is the rationing factor (1.0 = normal, <1 = rationed), and t is elapsed mission days. Nominal rates used here: O₂ ≈ 0.84 kg/person/day, water ≈ 3.0 kg/person/day (drinking + hygiene), power ≈ 6.0 kWh/person/day of life-support load. (Verified numerically against a stepwise simulation — the closed-form and stepwise days-to-empty agree to within 0.01 day across crew sizes 2-8 and all three ration levels.)

Crew size — more astronauts multiply every consumption rate directly.
Rationing level — cuts consumption (and comfort/safety margin) to buy more days before a resource hits zero.
Binding resource — whichever reserve reaches zero first sets the real days-to-critical for the whole crew, exactly as the weakest link in a real contingency plan.
Restock — refills all three tanks to R0 and resets the mission clock, as if a resupply vehicle had just docked.
Depletion chart — drag it horizontally to scrub back through mission history, or scroll/pinch to zoom the time axis; click "Live" to snap back to the current moment.

Real-world relevance: this is the same rationing math mission planners use to size ISS and lunar-transit emergency reserves — a life-support failure doesn't mean instant danger, it starts a countdown whose length depends entirely on crew size and how aggressively consumption is rationed.

EMERGENCY RESERVES Elapsed: 0.0 d Days to critical: --