https://www.usgs.gov/news/news-releases/state-news-releasesWe've been scanned. I'm not sure what instrument this was, but it flew a grid pattern over the area adjacent to our house(and our house as well on the first pass)where Freeport is about to open a new copper pit mine.
Couple of news releases on there about airborne geophys scans taking place. Normally electromagnetic scans either for geological structures or groundwater.