How exactly spacecraft, being at a huge distance from the Earth, can transmit information, including visual information, to our planet?
How did the first AMS photograph and transferred pictures to the ground? After all, in those days there was no digital photography. Films? Negatives? Scanning?
Regarding the film fired to Earth, these are not only the first spy satellites, this technology is still used today:
ru.wikipedia.org Cobalt-M - the last one used officially in 2015.
Mainly using the radio, because wire communication in these cases is ineffective for a number of reasons. But earlier, more exotic methods were used. So the first spy satellites simply fired off used film cassettes, which returned to Earth autonomously.