The CORONA program was a series of American strategic reconnaissance satellites produced and operated by the Central Intelligence Agency (CIA) Directorate of Science & Technology with substantial assistance from the U.S. Air Force. The CORONA satellites were used for photographic surveillance of the Soviet Union (USSR), China, and other areas beginning in June 1959 and ending in May 1972.

In 1957, the Soviet Union launched Sputnik 1, the first artificial Earth satellite. Officially, Sputnik was launched to correspond with the International Geophysical Year, a solar period that the International Council of Scientific Unions declared would be ideal for the launching of artificial satellites to study Earth and the Solar System. However, the launch led to public concern about the perceived technological gap between the West and the Soviet Union. The unanticipated success of the mission precipitated the Sputnik Crisis, and prompted President Dwight D. Eisenhower to authorize the Corona program, a top-priority reconnaissance program managed by the Air Force and CIA. Satellites were developed to photograph denied areas from space, provide information about Soviet missiles, and replace risky U-2 reconnaissance flights over Soviet territory.

CORONA began in 1956 as "Discoverer", part of the U.S. Air Force's WS-117L satellite reconnaissance and protection program. The WS-117L was based on recommendations and designs from the RAND Corporation. The program's primary goal was to develop a film-return photographic satellite to replace the U-2 spy plane in surveilling the Sino-Soviet Bloc and determining the disposition and speed of production of Soviet missiles and long-range bombers. The CORONA program was also used to produce maps and charts for the Department of Defense and other U.S. government mapping programs.

The CORONA project was pushed forward rapidly after the Soviets shot down a U-2 on 1 May 1960.

CORONA ultimately encompassed eight overlapping series of satellites (dubbed "Keyhole" or KH), launched from 1959 to 1972. CORONA was complemented and ultimately succeeded by the higher-resolution KH-7 Gambit and KH-8 Gambit 3 series of satellites.

A complementary but ultimately unsuccessful program was the SAMOS satellites, whose E-1 and E-2 series captured images on photographic film, developed the film aboard the satellite, scanned it electronically, and transmitted the images to ground stations. This system could generate only a few images per day, so later Samos satellites, such as the E-5 and the E-6, used the bucket-return approach pioneered with CORONA, but neither was successful.

The CORONA satellites were designated KH-1, KH-2, KH-3, KH-4, KH-4A and KH-4B. KH stood for "Key Hole" or "Keyhole" (Code number 1010), with the name being an analogy to the act of spying into a person's room by peering through their door's keyhole. The incrementing number indicated changes in the surveillance instrumentation, such as the change from single-panoramic to double-panoramic cameras. The "KH" naming system was first used in 1962 with KH-4, the earlier numbers being applied retroactively.

A list of CORONA launches compiled by the United States Geological Survey.