So ill add my 2p in here. Im a licenced Amateur radio operator (not that you even need to be to do this but it helps) and quite often follow what the ISS guys are doing.
For those of you interested, the Downlink frequency is 145.800MHz FM.
If you can tune into that frequency, you can often either hear the astronauts speaking down to earth (they run scheduled sessions with schools and the like) or receive some SSTV if they are broadcasting that.
Its simple enough to do, seen as it uses VHF frequencies and there obviously is nothing in the way when they are overhead but you do get doppler effect as they are going super speed... and also they are only contactable for a few mins until they fly over the horizon.
Here's a bit of SSTV i received from them this week :
https://www.instagram.com/p/BhfU4_ahfjXB5RaOiWjrz8smffJXiKwhvRmmhs0/?taken-by=kevamigaIts not perfect but its OK. I think its 9600 baud so that image takes around 50 seconds to be transmitted, so given you only have a few minutes the timing needs to be spot on.
Im not sure how anyone could really suggest that :
a. The ISS isn't circling a globe seen as literally people around the globe sent reports of it which are timed
b. If the earth was flat, and there was an ISS up there but it was all fakery and the like, a VHF signal would not disappear over the horizon. Granted it could be faked using directional antennas and the like but why? That would take massive amounts of effort to co-ordinate and i mean, NASA would just not allow it right?
c. If it was space junk or whatever... it can communicate 2-way with schools hahaha
Pretty simple stuff really.