In June 1959 KH-1, the first of the Corona series of American strategic imaging reconnaissance satellites was launched. Produced and operated by the Central Intelligence Agency Directorate of Science and Technology with assistance from the U.S. Air Force, the Corona satellites were used for photographic surveillance of the Soviet Union, the People's Republic of China and other areas. The 145th and last Corona satellite was launched on May 25, 1972 with its film recovered on May 31, 1972. Over its lifetime, CORONA provided photographic coverage totaling approximately 750,000,000 square miles of the earth’s surface.
"The Corona satellites used 31,500 feet (9,600 meters) of special 70 millimeter film with 24 inch (60 centimeter) focal length cameras. Initially orbiting at altitudes from 165 to 460 kilometers above the surface of the Earth, the cameras could resolve images on the ground down to 7.5 meters in diameter. The two KH-4 systems improved this resolution to 2.75 meters and 1.8 meters respectively, because they operated at lower orbital altitudes. . . .
"The first dozen or more Corona satellites and their launches were cloaked with disinformation as being part of a space technology development program called the Discoverer program. The first test launches for the Corona/Discoverer were carried out early in 1959. The first Corona launch containing a camera was carried out in June 1959 with the cover name Discoverer 4. This was a 750 kilogram satellite launched by a Thor-Agena rocket.
"The plan for the Corona program was for its satellites to return canisters of exposed film to the Earth in re-entry capsules, called by the slang term "film buckets", which were to be recovered in mid-air by a specially-equipped U.S. Air Force planes during their parachute descent. (The buckets were designed to float on the water for a short period of time for possible recovery by U.S. Navy ships, and then to sink if the recovery failed, via a water-dissolvable plug made of salt at the base of the capsule. This was for secrecy purposes.)" (Wikipedia article on Corona (satellite) accessed 11-29-2010).
"The return capsule of the Discoverer 13 mission, which launched August 10, 1960, was successfully recovered the next day. This was the first time that any object had been recovered successfully from orbit. After the mission of Discoverer 14, launch on August 18, 1960, its film bucket was successfully retrieved two days later by a C-119 Flying Boxcar transport plane. This was the first successful return of photographic film from orbit."
"CORONA enabled the US to specify verifiable terms of the Strategic Arms Limitation Treaty (SALT) with the Soviet Union in 1971. US negotiators confidently knew that photointerpreters could monitor changes in the size and characteristics of missile launchers, bombers, and submarines. Satellite imagery became the mainstay of the US arms-control verification process" (Central Intelligence Agency, CORONA: America's First Imaging Satellite Program, accessed 11-08-2014).