Scrubbing capacity comes from two substitutable resources — compressor/fan power drives gas flow through the sorbent bed, while sorbent mass/surface area sets how much CO₂ can be captured per pass. Neither alone determines throughput; capacity follows a diminishing-returns blend of both, so a lighter unit can hit the same rate as a heavier one only by burning more power, and vice versa. That substitutability is exactly what makes this a tradeoff surface rather than a single dial.
R_achievable = k · Power^0.55 · Weight^0.45
Coverage = min(1, R_achievable / R_target)
s = (R_target / R_achievable)^(1/(0.55+0.45))
CostAtTarget = s · (Weight + 12·Power) // minimal budget for the same P:W ratio
Score = 100 · Coverage · clamp(CostAtTarget / (Weight+12·Power), 0, 1)
- Power budget — raises achievable rate with diminishing returns (exponent 0.55); cheap to add, but alone it plateaus.
- Weight budget — sorbent bed size/area; also diminishing returns (exponent 0.45), and every kilogram is fuel cost on a real launch.
- Scrubbing target — the CO₂ removal rate the mission actually needs; the curve on the right is the exact power/weight frontier that meets it.
- Efficiency score — 100 only when the target is met and the budget isn't oversized for it; missing the target or over-building both cost points, because both failure modes waste the mission's resources.
The chart plots the power–weight plane. The curve is the Pareto frontier for the current target: every point on it is a different way to just barely hit the same scrubbing rate. Left of the curve is infeasible (target missed); right of it is feasible but increasingly over-provisioned the farther out you go.