Cygnus InstituteWhat the simple story leaves out
What the simple story leaves out.
Planet-encircling dust events every 3–4 Mars years (the 2018 event ended Opportunity). Suspended dust warms air aloft while cooling the surface: the opposite sign to the intended forcing. You would inject an engineered aerosol into an atmosphere already performing uncontrolled planetary-scale aerosol injection. Scavenging, coagulation, and dust-event reversal unresolved.
The sulfate–carbonate conflict: tested and refuted. Mars is sulfate-rich and carbonate-poor, and Meridiani jarosite records pore water below pH 4. CA-001 inferred that a wet Mars would therefore produce acidic brine hostile to carbonate, placing the carbon-burial pathway in chemical conflict with the natural chemistry of a wet planet. Constraint Analysis 002 tested that inference directly and found it false by a wide margin. The observed acidity is an artifact of low water-to-rock ratio and does not survive dilution to ocean scale. See Constraint Analysis 002 below.
Lacking a large moon, Mars's axial tilt wanders chaotically from ~0° to >60° over 10⁵–10⁷ years. Any terraformed state is metastable, requiring permanent active management. It forecloses the word 'permanent.'
Two objections weaker than they look.
MAVEN: present loss ~100 g/s ion escape, ~2–3 kg/s combined. An engineered thick atmosphere depletes over 10⁷–10⁸ years. Irrelevant on any engineering horizon. A magnetosphere is not required to retain gas.
Curiosity/RAD: 0.64 mSv/day at the surface under ~21 g/cm² of column. A 1 bar atmosphere provides ~1,000 g/cm², Earth's value. The mature end-state is self-shielding. A 1–2 T magnetic shield at Mars–Sun L1 matters only during transition and remains concept-level.