Cosmonautics primer by Ary Sternfeld, a Polish-born engineer trained in Nancy who emigrated to the USSR in 1935. French translation by Paul Kolodkine of the 1949 Russian edition (Полёт в мировое пространство), issued by Les Editeurs Français Réunis in the "Tout Savoir" series at the height of the early space race. The book offers an accessible survey of spaceflight principles: gravity and weightlessness, jet propulsion, the history of rockets, life aboard a cosmonef, optimal interplanetary trajectories, and the prospects of atomic-powered rockets. Fourteen chapters and six numerical tables (planetary characteristics, circular and parabolic velocities) round out a volume aimed at French-speaking general readers in the early Cold War.