KH-4 4 (Corona 42)

The KH-4, or Keyhole-4, represented the fourth iteration within the Corona program. This version introduced stereoscopic imaging capabilities with the Corona-M or Mural camera, consisting of two C''' (Corona triple-prime) cameras mounted with a 30-degree separation angle for forward and rear-looking perspectives. Additionally, a 4 cm index camera was included for specific imaging tasks. The Mural camera offered a ground resolution of 7.5 meters. Operating atop the Agena-D upper stage, the satellite facilitated attitude control during its mission, with film return managed by a single General Electric return vehicle (SRV). Upon mission completion, the film return capsule utilized its own solid-fuel retro motor for deorbiting, enabling mid-air recovery by specially equipped aircraft.