* a nanotechnology disaster
* Implementation of technologies that enable a global super-stable oppressive state.
* An AI disaster along the lines of a paper clip optimiser
* An AI or augmented intelligence that deprecates all lesser intelligences.
* The film version of I Robot.
* Biotech plague.
* Regression to a stable social and biological state optimising for lower intelligence or stagnation.
The way I think about this is that it's not just a backup. It's also deliberately introduced variation in environment and social structures that variegated Hunan civilization. Well develop technologies and social structures we wouldn't otherwise have that might help mitigate some of these risks. Semi-isolated from Earth, it would be at least partially protected from many of these threats. Of course, it could introduce new threats, but the isolation would work to protect Earth to some extent in that eventuality.
https://en.m.wikipedia.org/w/index.php?title=Global_catastro...