Spacecraft Resupply Logistics: Consumables Stock Simulator

Mission Parameters

Crew size 6

Consumption rate 11.5 kg/person/day

Resupply interval 90 days

Safety reserve margin 20%

Station Status

NOMINAL

Current stock

0 kg

Reserve remaining

0.0 days

Next shipment (planned)

0 kg

Mission elapsed

Day 0

How it works

A crew of size N consumes oxygen, water and food at a combined rate r (kg per person per day), so the station's onboard stock S drains as a simple linear ODE:

dS/dt = −N·r          (kg/day)
Reserve remaining = S / (N·r)   (days)

Every resupply interval T (days), a cargo vehicle is planned to launch carrying a shipment sized to cover the next full interval plus a safety margin m:

Shipment mass = N·r·T·(1 + m/100)

Real cargo launches slip. Each planned launch gets a random delay of up to 15% of the interval, exactly like real ISS resupply slips (Cygnus, Dragon, Progress all fly on windows, not guarantees). If the margin isn't large enough to absorb the slip, the visible stock hits zero before the next docking — a real stockout — and the status panel turns red.

Crew size / Consumption rate — set the daily burn rate N·r. The real ISS six-person crew burns roughly 11.5 kg/person/day of consumables and packaging.
Resupply interval — how far apart cargo missions are scheduled.
Safety reserve margin — extra buffer mass added to every shipment to absorb launch delays; the core logistics trade-off is shipment mass (cost, launch capacity) versus stockout risk.
The instanced canister rack around the station visualises the stock level directly — it empties as the crew consumes and refills the moment a cargo vehicle docks.

Station & consumables rack Cargo vehicle in transit

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