A forward-looking essay printed on 5 June 1969, five weeks before Apollo 11. Albert Ducrocq traces the genesis of astronautics (Tsiolkovsky, Oberth, Korolev, von Braun), defends the usefulness of space exploration against its critics, then surveys satellite applications: meteorology, agriculture, Earth resources, telecommunications. The second half imagines mankind settling the Moon (a scientific observatory of the Earth and Sun, an underground lunar city, lunar greenhouses) before a closing meditation on the "springtime of mankind" at the dawn of the 21st century.