It would be interesting to know how much greater the difficulty would be if you wanted a library that was recoverable from earth.
It’s certainly cool to have a cold storage repository on the moon; but, realistically, geographically distributed terrestrial copies have a pretty solid chance of surviving any event that leaves humanity and/or the meta-radroaches with the capacity to go recover something on the moon; as well as quite a few that don’t.
You obviously aren’t going to get a zillion years out of something with sophisticated active components; but I’d be curious to know how long you could keep, say, a radio transmitter audible from earth without terribly heroic measures running.
An overspecced 210Pu RTG, or 241Am, could stretch to some centuries of power; would it still be the weak link or does some other component go faster?
