1959-02-28 USA Discoverer 1

Discoverer 1 was the first of a series of satellites which were part of the CORONA reconnaissance satellite program. It was launched on a Thor-Agena A rocket on 28 February 1959 at 21:49:16 GMT from Vandenberg Air Force Base in California. It was a prototype of the KH-1 satellite, but did not contain either a camera or a film capsule. It was the first satellite launched toward the South Pole in an attempt to achieved a polar orbit, but was unsuccessful.

Discoverer 1 launch cover with H.Flick cachet, postmarked at Vandenberg Air Force Base, February 28, 1959.
The DISCOVERER program was managed by the Advanced Research Projects Agency (ARPA) of the U.S. 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 Lockheed U-2 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 U.S. government mapping programs. The goal of the program was not revealed to the public at that time; it was presented as a program to orbit large satellites to test satellite subsystems and investigate the communication and environmental aspects of placing humans in space, including carrying biological packages for return to Earth from orbit. In all, 38 Discoverer satellites were launched by February 1962, although the satellite reconnaissance program continued until 1972 as the CORONA project. The program documents were declassified in 1995.

Discoverer 1 launch cover with Goldcraft cachet, postmarked at Lompoc, February 28, 1959.
(Reference from Discoverer 1)