SPACE LOGISTICS PLANNING NOTE
Purpose: Test a generic inventory plan against demand, delay and a cargo mass limit.
Guide: https://yenra.com/interplanetary/
Modeling reference: https://arxiv.org/abs/2306.01107

This is an educational generic-stock exercise, not a real mission requirement or
a life-support design. All example inputs are invented. No losses, constant demand
and immediate usability on receipt are assumed. Volume/storage remain separate checks.

INPUTS
Material:
Demand rate r (kg/day):
Planned days to usable resupply T (days):
Additional delay allowance D (days):
Protected reserve R (kg, remaining AFTER the delay):
Container mass P (kg):
Gross cargo mass limit C (kg):

CALCULATIONS
Planned consumption = r*T (kg)
Delay consumption = r*D (kg)
Initial usable stock = r*(T+D)+R (kg)
Gross cargo = initial usable stock + P (kg)
Mass headroom = C - gross cargo (kg); negative means this mass limit fails.
Inventory after T days = r*D+R (kg)
Inventory after T+D days = R (kg)
Do not count packaging as usable stock or add the reserve twice.

WORKED EXAMPLE
r=2 kg/day; T=30 days; D=6 days; R=8 kg; P=5 kg; C=100 kg.
Planned consumption 60 kg; delay consumption 12 kg; usable stock 80 kg.
Gross cargo 85 kg; mass headroom 15 kg.
After day 30: 20 kg usable; after day 36: 8 kg protected reserve.
If D becomes 10 days: usable stock 88 kg; gross 93 kg; headroom 7 kg.

EVENT LEDGER (repeat rows; use times fine enough to reveal shortages)
Date/time | Opening usable kg | Received kg | Consumed kg | Losses kg | Closing kg
Closing = opening + received - consumed - losses.
Record receipt when usable at destination, not when launched.
Keep separate ledgers for non-substitutable materials.

Scenario changed and rationale:
First constraint violated and when:
Volume, storage environment, transfer and unloading checks:
Delivery opportunity / transit assumptions:
Demand/loss uncertainty and reserve rationale:
Unmodeled dependencies:
Review date and next check: