KH-4 CORONA

Early systems (KH-1, KH-2, KH-3 and KH-6) carried a single panoramic camera, or a single frame camera (KH-5), while the later systems (KH-4, KH-4A, and KH-4B) carried two panoramic cameras with 30 degrees separation angle. For KH-4, KH-4A,and KH-4B missions, the two cameras are referred to as fore (for forward looking) and aft (for rear looking). The KH-6 camera was programmed to tilt between fore and aft to cover the same land area twice during a photographic pass and thus to acquire stereo coverage. The satellites were designed to deorbit a film capsule (referred to as a "bucket")from space with mid-air recovery of the returning capsule by a specially equipped aircraft. Early systems operated with a single bucket, while later systems were configured with two buckets; the KH-4A was the first satellite with multiple film buckets.