 The Juno name derived from Von Braun wishing to make the satellite launch appear as peaceable as the Vanguard rocket, which was not a weapon, but was developed from a weather study rocket, the Viking.Since the Juno I was the same height as the Jupiter-C (21.2 meters), with the added fourth stage being hidden inside the shell, this vehicle which successfully launched the first orbital satellite of the United States is often incorrectly referred to as a Jupiter-C.The Jupiter-C was part of the IRBM project, and the sequence of manufacture of the rockets (which are not necessarily launched in order, and may be uprated as solutions to technical problems are worked out in tests) was considered a military secret.