Getting appropriate environmental approval for a major construction project is the LAW. You cannot just say as you seem to imply; “because my project is noble I don’t have to obey the law.” There will be significant environmental impact in building an observatory, no matter how worthy the project is. It will require an access road(s) –which may or may not exist depending where it is built, and any construction site whatsoever generates collateral damage to the surroundings. Doesn’t matter if it is an observatory, a school, a hospital, no matter what benefit the project will bring, it still has to go through the process of critical environmental review.

Environmantal protection laws do not exist because, to quote from the original post “activist groups in the US view observatories as easy targets to exploit for their agendas and for publicity”. They exist because there is a sustained societal history of special interests running roughshod over fragile ecosystems.