I've always found that human extinction argument rather dubious. The main mechanisms of extinction in those cases are atmospheric dust and fallout. If we can ma

I've always found that human extinction argument rather dubious. The main mechanisms of extinction in those cases are atmospheric dust and fallout. If we can maintain a closed ecosystem on Mars, we can do it underground, for a fraction of the cost, much less danger, and with a crew that rotates. Dinosaurs died out because they didn't have nuclear power plants or indoor greenhouses. A major impact would still be a tragedy of unimaginable proportions... but putting a bunch of technocrats on mars isn't going to change that either.