As space men the authors are pointedly down to earth: these are the technical resources, the stages of experimental advance, the political and economic hazards, obstacles, advantages to space conquest; set forth eagerly, persuasively, and without a daub of the fanciful. The questions, according to the authors, are no longer, Is it possible? and By what means? but How soon? and By whom first? They are concerned with the legal and social problems that go with the new Space Age, and the effects upon international relations. The book has often the air of an extremely detailed and elaborate editorial, in one of the more thoughtful, conservative papers. It is more for those interested in the practical business aspects of preparation for a traffic in the universe than for the scientific minded.