How did relay of photographs taken from satellites to analysts on the ground work before the ability to digitise photographs? I heard of film reels being sent back to earth, but how many would one craft have? and what would happen once the craft ran out of film?
With Corona, they would fit as many film reels as feasible, take all the photos then a special re-entry canister with the film would detach and head earthward, after parachute deployment they would be retrieved mid-air by modified aircraft then taken home.