It was entirely rational. Aviation pioneers and explorers were pursuing things they valued. They were fully aware of the risks, and it was worth it to them. I

It was entirely rational. Aviation pioneers and explorers were pursuing things they valued. They were fully aware of the risks, and it was worth it to them. I think the current most significant effort to colonize Mars is also rational: Elon Musk wants to do it because it's something that's valuable to him personally to accomplish. I don't think doing something (e.g. colonizing other planets) for the sake of our distant ancestors is rational. That is self-sacrificial. No value is being pursued.