Again, the rays themselves did not directly cause the death and destruction. Rather they messed up the atmosphere. On Mars, where the atmosphere is already toxi

Again, the rays themselves did not directly cause the death and destruction. Rather they messed up the atmosphere. On Mars, where the atmosphere is already toxic, this would be irrelevant. And there's no way to shield Earth against this at all. And nobody's going to be escaping to Mars. The wealthy and powerful already have their doomsday bunkers and hideouts; even a post-apocalyptic (such as after WW3) Earth would generally be a much more hospitable place than Mars will be.