A technical popularization of the foundations of astronautics, written by a CNES telecommunications engineer and prefaced by General Robert Aubinière, the agency's first director general. The book unfolds in three parts (principles of satellite motion, the rocket, the satellite) leading the reader from orbital mechanics to overall satellite design, telecommunications satellites and crewed flight, including an assessment of the Gemini programme. Updated paperback edition (© 1967-1969) of the original published by Hermann in 1967.