Third revised edition (1971) of volume no. 397 in the "Que sais-je?" series, first published in 1949. Across 128 pages, Lionel Laming (a science graduate and ENSPM-trained engineer) surveys the entire field of astronautics: a critique of "fanciful methods" (space cannon, rotating catapult, antigravity), principles of self-propulsion, propellants, non-propellant propulsion (fission- and radio-thermal, electrothermal, plasma, ion, photon), space biology, artificial satellites, planetary exploration, and the civilian and military applications of astronautics, through to interstellar communication. The volume incorporates the achievements of Apollo, the Mariner and Venusik probes and the early Grand Tour planning, offering a post-1969 panorama of the field.