A few years back someone wrote an article (to a science journal I think) asking if it was possible that the dinosaurs had high technology but all evidence of it had vanished in the millions of years that have passed.
Some dinosaurs were around for millions of years, which is a phenomenal amount of time compared to human history, and if humans go extinct anytime soon we may leave very little trace of our technology for a species 60 million years after us.
Two factors weighed against it: plant diversity and evidence on the moon.
The first comes from the argument that any sufficiently advanced civilization will travel around the globe, so fossil records will show the same plants everywhere. It's tricky to determine this but the evidence seemed against it.
The second is simply that any high technology civilization will eventually travel to the moon, which allows for a much more undisturbed record.
The second is simply that any high technology civilization will eventually travel to the moon, which allows for a much more undisturbed record.
If we didn't already know where the lunar landers touched down, do we really think we'd be able to find them again with just a telescope? That's a lot of area to search.
The point is ... there is no question that our satellites would have found such evidence by now. We may not tell the general public ... but we would definitely have a good idea of where to look for evidence.
A lot of meteorites would be necessary for this to happen. Of course depending on how big and widespread the evidence would be. Some "well-directed" hits, and our footprints and scientific things would be gone. If they had a bigger base, they probably dug a lot of underground tunnels which are a lot more resistand (one of the reasons to build them to begin with).
There's a pretty key difference. Deploying countermeasures against an extinction-level asteroid strike is a realistic possibility with current technology. An extraterrestrial human presence which could survive an extinction event just... isn't. Sad as it is to say.
