On February 2, 1967, the United States Air Force launched a top-secret surveillance satellite called Keyhole-7. This was the 36th out of 38 satellites launched by the Air Force under a project codenamed Gambit.
One of the most important purposes for the construction of satellites and platforms, which was considered from the beginning, was military purposes, based on which satellites entered space under the name of spy satellites to collect military information.
The first group of military satellites launched for initial testing were the Keyhole series. These satellites used the film transmission system from 1960 to 1972. All the satellites of this series, which reached 150, used cameras capable of video recording or electro-optical cameras.
Keyhole-7 had a spatial resolution of seven centimeters and acquired some of the first high-resolution spy satellite images of places including China and the Soviet Union.
Keyhole-7 spent only about ten days in orbit before returning to Earth with rolls of incomplete film. These rolls landed in capsules and the Air Force had to find and retrieve them.
Thousands of images from these spy satellite missions were released in 2002.