>>I'm not sure why you think that survivors on Earth, struggling for survival in a barren wasteland, would be more likely to fall into war than the inhabitants

>>I'm not sure why you think that survivors on Earth, struggling for survival in a barren wasteland, would be more likely to fall into war than the inhabitants of Mars, struggling for survival in a barren wasteland. A fully self-sufficient Mars colony would not, by definition, be "struggling for survival." >> A technological civilization like ours depends on a body of knowledge that's way too big to fit in one or 1000 people's heads. A fully self-sufficient Mars colony would have plenty of computers that can store data. In fact, since the goal of such a colony would be to act as Earth's backup, we would most likely have most of the Earth's combined knowledge stored in a large datacenter underneath the Martian surface. On the other hand, the shockwave from an asteroid that wipes 90% of the population on Earth would also instantly fry most electronics and render most technology useless. Like I said, it would send civilization back a thousand years. Sure, we would still have the knowledge in people's brains, but it turns out knowledge can be forgotten, especially when not actively recalled by the brain. When all your scientists have to become farmers, it is not likely that humanity would be able to retain all the knowledge it has collected over the past millenia.