Life-Support Economies of Scale

Colony Size

Population 6

Crew — current mission scale (6–12)

Engineering Assumptions

Economies-of-scale exponent b 0.75

Spare (redundant) modules 2

Capacity per module (people) 8

Live Readouts

Total ECLSS mass

Specific mass /person

Life-support modules (active + spare)

How it works

Bulk ECLSS hardware (tankage, structure, thermal radiators) doesn't scale 1:1 with crew size — bigger vessels and reactors have a better volume-to-surface ratio, a classic chemical-engineering "six-tenths rule":

M_bulk(N) = M0 · N^b        (b < 1 → economies of scale)

Separately, a colony needs whole spare recycling/scrubber modules to survive a single-unit failure, not a fractional one. A tiny crew still needs the same integer number of spares as a huge one, so the spare fraction shrinks as the crew grows:

modules_active = ceil(N / capacity_per_module)
modules_total  = modules_active + spares
redundancy(N)  = modules_total / modules_active

Multiplying the two effects gives the total installed mass and the mass per colonist:

M_total(N)      = M_bulk(N) · redundancy(N)
specific_mass(N) = M_total(N) / N

Population slider — logarithmic, spans a 6-person crew to a 5,000-colonist planetary base.
Exponent b — how strongly bulk hardware benefits from scale; lower b = stronger economies of scale.
Spare modules — fixed redundancy count (N+k sizing); its overhead share shrinks as more active modules are added.
Capacity per module — how many people one recycling/scrubber unit serves, setting how many modules are needed at all.

The chart plots specific mass against population on a log-log scale — a straight power-law decline from bulk economies of scale, with a bump at small N where redundancy overhead dominates. This is why a 6-person crew's per-capita life-support mass is crushing, and why the curve flattens well before a planetary base.

Colony pods Active LS modules Spare (redundant) modules

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