These satellites that dropped film were a part of the Corona project. Corona was a project of the CIA to watch the activities of the USSR and the People’s Republic of China.
One hundred and forty-four satellites were used, and of those satellites one hundred and two of them returned photographs that could be used. The film within each of the satellites had to be dropped out of the satellite and be collected by planes.
The capsules that held the film were created by General Electrics and were specially made because they had to be capable of surviving a drop through the atmosphere.
The capsules had parachutes that came out at 60,000 feet, so they could be reclaimed by an airplane with a claw. Unfortunately catching the capsules wasn’t an exact science, so they often got missed.
To remedy the issue of capsules being missed by planes, they were designed with several features. For example, the capsules had salt plugs that dissolved after a few days if it fell into the ocean.
That way if the capsules weren’t caught in midair or recovered in the water by the US navy, they would sink and wouldn’t get into enemy hands. Eventually, they also had directions to claim a reward in eight languages if returned to the United States.