Out of the Cradle (book)
Out of the Cradle: Exploring the Frontiers beyond Earth is a 1984 book written and illustrated by planetary scientist William K. Hartmann, Ron Miller and Pamela Lee. "Cradle" describes potential manned space missions to the planets, moons and asteroids of the Solar System. The approximately 100 space art illustrations were in large part based on photographs from the unmanned space probes "Pioneer 11", "Voyager 1", and the Viking Lander, available at the time of publication, with scientific extrapolation of the likely appearance of various planetary surfaces. The title is derived from a quote from Konstantin  Tsiolkovsky, included in the preface: "Earth is the cradle of humanity, but one cannot live in the cradle forever." The book is notable for introducing (on p. 182) Hartmann's 'golden rule' of space exploration: "Space exploration must be carried out in a way so as to reduce, not aggravate, tensions in human society". Reception. "Cradle" has received positive critical academic reviews, including from the "Journal of the Royal Astronomical Society of Canada". It has been recommended as a teaching aid for science classes.