Digital cameras were developed so spy satellites could send images back to earth more quickly. Before digital cameras in 1976, spy satellites used film. After the film was shot, the satellites loaded the footage into capsules and dropped them from orbit into the atmosphere for collection.
Philip K. Dick, the author of the science fiction novel “Do Androids Dream of Electric Sheep?”, published in 1968, said “There will come a time when it isn’t ‘They’re spying on me through my phone’ anymore. Eventually, it will be ‘My phone is spying on me’.” His novel was adapted into the 1982 film “Blade Runner”.