> One that they didn't mention was our artifacts on the moon which will last 100 million years or so. Geostationary and HEO satellites will stay for a while but I'm not exactly sure how long.

Erosion due to micrometeorites erodes the surface of the moon at 1mm per 1e6 years [1]. I wonder whether erosion of human-made moon artifacts will commence at a comparable rate.

Note that the hull thickness of the apollo lander is just 0.3 mm [2]. Part of the propulsion system, tanks etc. would be the components to last longest, butt 100 million years may be quite a stretch.

[1] https://mauricejscollins.wixsite.com/moonscience

[2] https://space.stackexchange.com/questions/924/what-would-hav...