> What does humankind make that would survive 60 million years into the future, and if some other advanced industrial civilization had existed 60 million years

> What does humankind make that would survive 60 million years into the future, and if some other advanced industrial civilization had existed 60 million years ago, how would we know? I wonder if a swarm of artificial satellites that are little more than time capsules on various highly stable orbits, combined with radioactive markers/beacons on the moon that is arranged to somehow point towards the swarm, might survive that long? The moon's orbit is stable on the order of billions of years [1], but surface impacts might bury any artifacts we leave, so radiation is likely the only way an artifact can stand out millions of years from now. If the swarm is a solid procession of one satellite passing near the Earth once every 50 years, then the markers' arrangement might be able to point to that intersection somehow. Bonus points if we can figure out passively-controlled, self-repairing solar sails for better detection. I haven't sketched the math yet though, so I don't know if we're talking about more satellites than we can create (would more than likely require von Neumann mining bots on an asteroid to produce, and definitely more mass than we can realistically lift at this time). This has the advantage of letting us continuously launch updated capsules, as well as capture and update probes (like modifying a massive continuous loop) if our civilization lives that long. I really Iaian Banks' idea of a civilization "restart button": deep space-resident AI-manned ships that all but just wander and hibernate within vast gulfs of vacuum, equipped with the tech necessary to reboot their civilization, and run silent all the time except when they opt-out of the service. That requires AGI and a fictional inexhaustible energy source to pull off, so we have to settle for what we can do for now. [1] https://astronomy.stackexchange.com/questions/19658/what-defines-a-stable-orbit https://astronomy.stackexchange.com/questions/19658/what-def...