Terraforming Mars: Requirements on Mass, Forcing, and Industrial Throughput

Terraforming Mars is constrained by a small set of planet-scale closures: atmospheric mass required to reach pressure and composition targets, radiative perturbation required to raise surface temperature, industrial throughput and energy required to supply gases or absorbers, and stability against collapse, escape, and geochemical sequestration. We present an order-of-magnitude engineering synthesis of leading proposed mechanisms (endogenous CO2 release, synthetic super-greenhouse gases, CO2–H2 collision-induced absorption, engineered aerosols/nanoparticles, orbital mirrors/albedo modification, and regional solid-state greenhouse “paraterraforming”). Key results are: (i) pressure targets map directly to atmospheric mass via Matm ≃4πR2 MarsPs/gMars, implying 1017–1018 kg inventories for human-relevant pressures; (ii) accessible CO2 reservoirs plausibly provide at most∼20 mbar, yielding ≲ 10 K warming under current insolation and falling far short of global melt requirements; (iii) raising global-mean surface temperature to Ts ∼250–273 K at current insolation requires a broadband IR optical depth τIR ∼2–4 in a minimal grey closure; (iv) breathable endpoints are dominated by O2 and buffer-gas mass and require ≳ 1025 J (∼3 ×1018 kWh) even at thermodynamic minima, implying M-dot ∼107–108 kg s−1 and PW-class power for century-scale build times and an unavoidable civilization-scale energy-cost floor; and (v) mass-efficient warming approaches (e.g., aerosols) are typically maintenance-limited, whereas one-shot forcing (mirrors) is structure-area-limited. We conclude that near-term habitability gains are most credible via regional paraterraforming, while global endpoints require multi-century planetary industry with explicit closure on power, throughput, and climate control authority.