Corona was the name of a series of the U.S. military reconnaissance satellites operated under a CIA program run by the Directorate of Science & Technology with substantial assistance from the US Air Force, used for photographic surveillance of the Soviet Union, China and other areas from June 1959 until May 1972. The project name is sometimes given as CORONA, but it is a codeword, not an acronym.
The secret spy satellite was dubbed Corona by the CIA. To disguise its true purpose, it was given the cover name Discoverer and described as a scientific research program.
The Corona Story, December 1988 [182 Pages, 7.9MB]
CORONA: America's First Satellite Program, 1995 [362 Pages]
Discoverer/Corona General Briefing Portfolio - 22 January 1959 - Document received from the NRO.