The satellite was launched from Cape Canaveral (now Cape Kennedy) in Florida at 10:48 P.M. EST on 31 January 1958 by the Jupiter C vehicle - a special modification of the Redstone ballistic missile that was designed, built, and launched by the Army Ballistic Missile Agency (ABMA) under the direction of Doctor Wernher Von Braun. Jupiter C, a direct descendant of the German A-4 (V-2) rocket, was originally developed in 1955-1956 as a high-performance rocket for testing purposes.
The Jupiter C has its origins in the United States Army's Project Orbiter in 1954. The project was canceled in 1955, however when the decision was made to proceed with Project Vanguard.
