Thor Agena rocket model on engineer's desk
Today marks the 50th anniversary of the failure of the Discovery IV failure to achieve orbit. The payload was a prototype device equipped with the KH-1 camera. These test flights would lead to the development of the Corona project spy satellite program. The camera would take its photos of the intended target, then at the appropriate orbit, eject the film cannister in a pod designed to survive re-entry and be recovered. However, after launch on a Thor-Agena-A rocket, Discoverer IV failed to reach orbit at all.
The objective was to monitor Soviet buildup of nuclear forces and long-range bombers. Of course, it was classified (until 1995!) and instead was presented to the public as a test of future technology needed to put humans in space and return them safely to the Earth.
Days earlier, on the 22nd, the Vanguard SLV-6 attempted to orbit a satellite but also failed. By now, 2 of the Vanguard missions had been successful, but with this launch the failures stood at 8!