Interplanetary Flight: An Introduction to Astronautics is a short, modestly technical introduction to space exploration written by Arthur C. Clarke, and published in 1950. It includes material accessible to readers with a high-school level of science and technical education, covering the elements of orbital mechanics, rocket design and performance, various applications of Earth satellites, a discussion of the more interesting and accessible destinations in the Solar System (such as they were understood at the time of writing), and in a final chapter covering the rationale and value of human expansion off the Earth. Source: Wikipedia (en)