The KH-4 (Keyhole-4) was fourth version in the Corona-program to build an optical reconnaissance satellite. KH-4 24 also carried the RM 5 radiometer payload for background measurements for the MIDAS program. December 21, 1963 at 21:45 UTC · Launch Successful Thor SLV-2A Agena D — United States Air Force, to Low Earth Orbit Space Launch Complex 2W, Vandenberg SFB, CA, USA The world's 293rd orbital launch attempt, and 69th of 1963. Data: Launch Library 2, The Space Devs. Image via The Space Devs.