Explorer 5

Explorer 5 was a United States satellite with a mass of 17.24 kg. It was the last of the original series of Explorers built, designed, and operated by the Jet Propulsion Laboratory. 
It launched atop a Juno I rocket on August 24, 1958 from Launch Complex 5, but failed when the rocket's first stage collided with its second stage after separation, causing the upper stage firing angle to be off.
Explorer 5 had been intended to be one of two satellites used to gather data for Project Argus.