Terraforming Mars: Mass, Forcing, and Industrial Throughput Constraints

Terraforming Mars can be evaluated with a set of system-level constraints linking (i) target pressures & compositions to required atmospheric inventories, (ii) target surface temperatures to the required radiative control, (iii) inventories & climate agents to sustained industrial throughput & power over a build time, (iv) persistence against collapse, escape, geochemical sinks. We use order-of-magnitude scalings to compare endogenous CO2 release, synthetic super-greenhouse gases, CO2-H2 collision-induced absorption, engineered aerosols/nanoparticles, orbital mirrors, regional paraterraforming. We find: (1) human-relevant pressures imply exaton-class inventories, because Mars requires 3.89 x 10^15 kg of atmosphere per mbar of global mean surface pressure; (2) accessible endogenous CO2 is best treated as ~10s of mbar resource, with a 20 mbar case yielding <10 K warming under present insolation; (3) mean surface temperatures of 250-273 K require either effective IR opacity of ~2-4 or direct absorbed-solar forcing of ~100 W/m^2, implying reflector areas of ~10^{13}-10^{14} m^2 together with large deployment, control, durability, replacement burdens; (4) breathable open-surface endpoints are dominated by O2 and N2 inventories and by a minimum oxygenation work exceeding 10^{25} J, implying average build rates of 10^7-10^8 kg/s and average power from multi-100 TW to PW for century-to-millennial build times before inefficiencies and sink filling. We conclude that regional habitability via paraterraforming/covered-area strategies are plausible on near-term industrial scales, whereas no credible open-atmosphere pathway is identified to a Mars permitting pressure-unassisted human exposure or a breathable surface atmosphere without exaton-class volatile supply, multi-century planetary industry, + sustained climate actuation, retention, durability management, replacement against sinks and loss.