During his time at the Army Ballistics Missile Agency (ABMA) was the first time Wernher used his knowledge in rocketry to make a rocket that was designed to go into space, and not to be used as a weapon. The Jupiter-C was based almost entirely from the V-2 rocket Wernher created during his time in Germany, and was originally made as a high-performance test rocket. After the creation of the Explorer I satellite, all that was needed was a booster rocket to get it into space was a booster rocket. After that, the Jet Propulsion Laboratory (JPL) and the Army Ballistics Missile Agency (ABMA) teamed up to get the Explorer I into space. The result of this dynamic duo resulted in a more efficient Jupiter C rocket that was launched in present-day Cape Kennedy at 10:48 PM EST on January 31, 1958.
The picture above shows the Jupiter-C right before a launch.