Third updated edition of this classic popularization, surveying artificial satellite science fifteen years after Sputnik 1. Five chapters cover orbital mechanics, satellite physical decay, launch systems, a gallery of landmark satellites (Sputniks, Grapefruit, Echo, West Ford, Elektron, Polyot), and three application families: scientific satellites, telecommunications (through Intelsat IV, 1971), and crewed spaceflight (from Gagarin through Apollo and Salyut 1). A chronological list records all Soviet and American crewed flights through end-1971.