This book provides a detailed history of unmanned missions of exploration of our Solar System. It uses sources only recently made available on the Soviet space program, in addition to some obscure and rarely used references on the European space program. Unflown European projects of the 1960s and 1970s, a subject never before treated, are also be covered. As in their previous book 'Lunar Exploration' the subject is treated wherever possible from an engineering and scientific standpoint. Technical descriptions of the spacecraft, of their mission designs and of instrumentations are provided. Scientific results are discussed in considerable depth, together with details of mission management. The book comprehensively covers missions and results from the 1950s until the present day, and some of the latest missions and their results appear in a popular science book for the first time.