Altogether, in the United States and other countries, billions of dollars are now being spent on the development of a technology which gives every indication of being or becoming an astronautical technology. This is extremely gratifying to all those who, during the first part of this century, fought for recognition of space travel as a serious, practical and worthwhile effort-not at some future time, but right now, in this century and in this age of ours. The campaign for technical and scientific recognition of space flight is won. However, the fight for recognition of astronautics as a vital part of man's future, rather than as just an accepted technical or scientific specialty, has hardly begun. Astronautics is the science of operating in space and traveling to other worlds. The implications are such that it now becomes increasingly important to develop the philosophy, as well as the utilitarian aspects, of this new science. Since space travel has been recognized by its protagonists as one of the most fundamental and outstanding concepts in the history of man, it is not surprising that a good deal of thinking has already been done on this subject, beginning with Konstantin Ziolkowsky, whose ardent belief in the cosmic mission of mankind heralded the dawn of astronautic pioneering some 60 years ago, and continuing with Hermann Oberth, Willy Ley, A.C. Clarke, A.V. Cleaver, Wernher von Braun and Eugen Saenger. A certain mutual overlapping of thoughts and arguments advanced by these pioneers and others, is unavoidable, in view of the principal agreement among all concerned over the promotion of space travel. However, the philosophy of astronautics is young and fertile. Its countless implications are far from exhausted. For this reason, the author, concerned for some 20 years with the study and the advocacy of astronautics as a technical, as well as a cultural, mission, submits a few additional thoughts on this subject. The concept of space travel carries with it enormous impact, because it challenges man on practically all fronts of his physical and spiritual existence. The idea of traveling to other celestial bodies reflects to the highest degree the independence and agility of the human mind. It lends ultimate dignity to man's technical and scientific endeavors. Above all, it touches on the philosophy of his very existence. As a result, the concept of space travel disregards national borders, refuses to recognize differences of historical or ethnological origin, and penetrates the fiber of one sociological or political creed as fast as that of the next. As a technical concept, astronautics is all-embracing, and more revolutionary than anything conceived so far, including even atomic technology. As a scientific concept, it is bound to stimulate and rejuvenate practically all fields from astronomy to zoology. Its sociological and political implications are such that future generations may well describe as "cautious" even the boldest predictions of our time.