Beskrivning : Discoverer 4 was a first generation, low resolution Air Force surveillance satellite launched from Vandenberg AFB aboard a Thor Agena-A rocket. The mission failed because the satellite failed to achieve orbit.
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 the U2 spyplanes.