As Cold War tensions grew in the 1950s, the U.S. relied upon the U-2 high-altitude reconnaissance spy planes and reconnaissance balloons from its Genetrix Program. But these tools, unable to surveil some of the darkest and farthest reaches deep within the USSR, did not provide enough aerial coverage to accurately determine Soviet military operations, movements, and capabilities.

Instead, the US was forced to reach even higher with its reconnaissance missions using the “Keyhole” series of satellites. Unlike modern digital spy satellites, the KH-series relied on the use of physical film that had to be secretly jettisoned and returned to Earth. To keep the film out of enemy hands, each KH satellite utilized a simple but effective trick. When their missions were complete, the KH satellites dumped their top-secret film into a reentry capsule and dropped it back to Earth. If the fiery descent went to plan, the capsule would jettison its heat shield and a parachute would deploy. All that would be left was for an airplane to hook it in mid-air some 60,000 feet above the ground...