On February 2, 1967, the U.S. Air Force launched a top-secret surveillance satellite called Key Hole 7-36.

This was the 36th of 38 satellites that the Air Force launched under a project codenamed Gambit. These satellites acquired some of the first high-resolution spy satellite images of places including China, the former Soviet Union, Israel and more. Key Hole 7-36 only spent about 10 days in orbit before returning to Earth with rolls of undeveloped film, which arrived in capsules that the Air Force then had to find and retrieve. Thousands of images from these spy satellite missions were declassified in 2002.