For those who don't follow astronomy closely this is the background on the LSST, aka the Vera C. Rubin Observatory. TL;DR: Powerful wide-aperture telescope will survey a huge amount of the sky and identify many more faint/small objects floating around the solar system than current telescopes used for the same purpose. Goes online in 2022.

I started thinking about this since recently finishing Avi Loeb's new book. It's a great book but IMO could've been about half the size (first half is great.)

Professor Loeb's hypothesis is that 'Oumuamua being an artificial object created by an alien civilization is the current best-fit for the available data. The tumbling object has an extreme aspect ratio (roughly the size of a football field but pancake shaped; not likely a cigar as commonly depicted), is very reflective, and experienced an unusual smooth push when passing by the sun not attributable to the sun's gravity. It displayed no characteristics of cometary outgassing (as negatively detected by Spitzer) leaving only the possibility of solar radiation pressure being responsible for the push. To allow for solar radiation pressure to be the source of the push the object would have to be extremely thin, <1mm. We know of nothing like this existing in nature and proposed natural explanations involve never before seen extremely contrived constructions, e.g. loosely bound clump of cosmic dust bunnies that somehow tumble together and maintain integrity, or a pure hydrogen "iceberg".

How much weight you assign to Professor Loeb's hypothesis is up to you but I would image the DoD would at least take it somewhat more seriously than mainstream science commentators appear to be given the potential stakes. This isn't some crackpot making a wild evidence-free claim. He was the chair of the astronomy department at Harvard to name just one of his credentials.

If alien technological debris is floating through our solar system all the time, imaging and capture of it could give one country a considerable technological advantage over the others if they are able to partially reverse engineer whatever it is. I don't know how likely it is that it would provide much of an advantage but it seems the potential here is non-zero and the magnitude of the advantage could be immense (imagine leaping ahead thousands or even millions of years in technology.)

This leads me to wonder if governments have already begun/completed their own highly specialized version(s) of the LSST. The LSST began construction in 2015 and 'Oumuamua wasn't discovered until 2017. 2017 is when Professor Loeb proposed his theory. So I would imagine this has been on government radar (so to speak) since at the very least then. If I were China or the US governments I would have already begun preparing to analyze and capture such an object should we find another again. Catching up to 'Oumumua now is virtually impossible with our current technology but probabilities dictate the LSST should find at least 1 strange 'Oumuamua-like object per year. Waiting for the LSST to identify candidates could introduce unnecessary delay in this effort. If I were a world power I'd have begun priority construction of my own version of the LSST while simultaneously designing imaging and capture missions. I would imagine the race here has been long underway. (Notice when "Space Force" became a thing.)

My question is, would it be practical to hide such a telescope from the rest of the world given the ubiquity of things like Google Maps and government satellites? I guess it wouldn't need to be hidden but I haven't heard of secret government observatories before. Maybe someone else has? Maybe reddit sleuths haven't thought about looking for such things yet?

Anyway, I'd be interested in hearing about other ideas about this situation.