 The DISCOVERER program was managed by the Advanced Research Projects Agency (ARPA) of the Department of Defense and the U.S. Air Force.The primary goal of the program was to develop a film-return photographic surveillance satellite to assess how rapidly the Soviet Union was producing long-range bombers and ballistic missiles and where they were being deployed and to take photos over the Sino-Soviet bloc to replace the U2 spyplanes.It was part of the secret CORONA program which was also used to produce maps and charts for the Department of Defense and other US government mapping programs.