The KH-4 (Keyhole-4) was fourth version in the Corona-program to build an optical reconnaissance satellite. April 18, 1962 at 00:53 UTC · Launch Successful Thor DM-21 Agena-B — United States Air Force, to Low Earth Orbit Space Launch Complex 1E, Vandenberg SFB, CA, USA The world's 156th orbital launch attempt, and 14th of 1962. Data: Launch Library 2, The Space Devs. Image by USAF via The Space Devs.