A popular science book published by Hachette in 1957, written before the launch of Sputnik (4 October 1957) and based entirely on documentation from the American Vanguard programme. Pierre Rousseau covers the scientific foundations of artificial satellites (atmospheric physics, orbital mechanics), a historical survey of astronautics from Tsiolkovsky to Goddard, the prospects of space stations and lunar travel, and the challenges of interplanetary and interstellar flight. A publisher's prefatory note states that no changes were needed for the text to apply equally to the Soviet satellite.