Discoverer 4 was the fourth in a series of reconnaissance satellites, however, it failed to reach orbit when the Agena engine underperformed and failed to place the capsule into orbit. June 25, 1959 at 22:47 UTC · Launch Failure Thor Agena A — United States Air Force, to Polar Orbit Space Launch Complex 1E, Vandenberg SFB, CA, USA The world's 41st orbital launch attempt, and 10th of 1959. Data: Launch Library 2, The Space Devs.