The Mars backup plan seems kinda dumb to me because Mars is worse as is than all but the very worst post-apocalyptic Earth scenarios. Just build bunkers here a

The Mars backup plan seems kinda dumb to me because Mars is worse as is than all but the very worst post-apocalyptic Earth scenarios. Just build bunkers here and staff them in shifts. Much cheaper. Your remaining threats for which Mars would be better than "ruined" Earth are something like a grey goo event, or an asteroid so large that it liquefies much of the crust (killing everyone in all your bunkers). So, a fair bit bigger than the one that killed the Dinosaurs. I am very interested in watching people try to colonize Mars, but find the "backup for Earth" argument ridiculous, especially if presented as something urgent.