This is a POPPY satellite of the multiface design.
POPPY is the code name given to a series of U.S. intelligence satellites operated by the National Reconnaissance Office. The POPPY satellites recorded ELINT data, targeting radar installations in the Soviet Union.
The existence of the POPPY program was declassified by the NRO in September 2005, although most of the details about its capabilities and operation are still classified.
There were seven launches of POPPY satellites from Vandenberg Air Force Base from 1962 until 1971, all of which were successful. The program continued until August 1977.