スプートニク・ショック
The Vanguard launch vehicle was the civilian rocket program in development for this purpose, so the administration ordered ABMA's research director, Wernher von Braun, not to attempt any satellite launches. The Vanguard rocket failed on its first attempt to launch the Vanguard satellite in December 1957, crashing back to the pad and exploding. Following this setback and in the wake of the Sputnik crisis, the administration changed course and turned to the Army, asking ABMA and von Braun to launch the JPL-built satellite as soon as possible.