Space habitats more expensive than terraforming Mars?
No, more expensive than Mars habitats, for the reasons you mentioned. When I said “and easier to terraform,” I meant that as a bonus, not as a requirement. Closed habitats seem like a reasonable norm for small societies in hostile conditions.
independent one-in-a-hundred chance
Sure; but there must also be dependent chances (like gamma ray bursts or ubiquitous design faults or so on). It seems difficult to have the baseline dependent fragility of orbital habitats at lower than the baseline dependent fragility of Earth. I would rather have 10 Cheyenne Mountain-style habitats a bit below the Earth’s surface than 10 orbital habitats- and, again, at equal cost expect to have a lot more ones on Earth than off it.
Ten Cheyenne Mountains are fine—as long as nothing happens to the Earth that would stop the people surviving in them from resuming agriculture on the Earth’s surface (whether or not under glass). I’d like there to be humans elsewhere in the solar system that are already growing their own food as a hedge against any of the things, already thought of or not, that can take out a planet but not a solar system.
No, more expensive than Mars habitats, for the reasons you mentioned. When I said “and easier to terraform,” I meant that as a bonus, not as a requirement. Closed habitats seem like a reasonable norm for small societies in hostile conditions.
Sure; but there must also be dependent chances (like gamma ray bursts or ubiquitous design faults or so on). It seems difficult to have the baseline dependent fragility of orbital habitats at lower than the baseline dependent fragility of Earth. I would rather have 10 Cheyenne Mountain-style habitats a bit below the Earth’s surface than 10 orbital habitats- and, again, at equal cost expect to have a lot more ones on Earth than off it.
Ten Cheyenne Mountains are fine—as long as nothing happens to the Earth that would stop the people surviving in them from resuming agriculture on the Earth’s surface (whether or not under glass). I’d like there to be humans elsewhere in the solar system that are already growing their own food as a hedge against any of the things, already thought of or not, that can take out a planet but not a solar system.