A first-hand account of the American artificial satellite program (Project Vanguard), written by the Director of Information of the US Federal Civil Defense Administration and published in French translation in 1957. The book traces President Eisenhower's announcement of July 29, 1955, the scientific origins of the project (atmospheric research, V-2 rockets, International Geophysical Year), the contributions of the National Science Foundation and the Navy, and the technical details of the Vanguard satellite and its launcher. A contemporary witness account written before the Sputnik launch, it captures American optimism at the dawn of the Space Age.