This thread reminds me of a old mystery - I was travelling back from Japan - LHR back in the 90s and at some point not long, perhaps 2/3 hours after take off was passing over uninhabited snow-covered terrain (Russia? China?). But the puzzling thing was i was seeing lots of parallel lines on the ground. My thoughts were fences, but too visible and too long. Power lines - too many in parallel. some kind of antenna or radar array?
I've since checked on google earth but find nothing similar.
Does that ring any bells with anyone who does this route?