Orbital Resupply Buffer Stock (2D)

A space station cannot manufacture the water, oxygen and CO₂-scrubber sorbent its crew consumes every day — every gram has to arrive on a cargo vehicle launched from Earth. This simulator models that resupply chain as a continuous-review (s, Q) inventory system: a consumable buffer drains at a controllable daily rate, a cargo launch is triggered automatically once the buffer falls to a reorder point, and the delivery arrives after a stochastic transit time shaped by a lead-time-jitter control. A top-down 2D orbit map (drag to pan, scroll to zoom) shows the station's path, the fixed launch site, and the cargo vehicle's transit arc, while live readouts track the buffer level, days of runway remaining, missions flown, and a stockout-risk percentage computed from the same safety-stock statistics real mission planners use to size resupply cadence for the ISS.