> if Russia just put one on a satellite and didn't tell anyone, does anyone have any way to notice? Yes. Satellites are not transparent so they occlude the sk

> if Russia just put one on a satellite and didn't tell anyone, does anyone have any way to notice? Yes. Satellites are not transparent so they occlude the sky behind them for anyone who is watching, which allows discovery of new satellites. Imaging them and determining trajectory via doppler etc comes after you know it's there. See: https://www.space.com/amateur-satellite-trackers-on-global-lookout.html https://www.space.com/amateur-satellite-trackers-on-global-l...