This book describes the "halcyon years" of air and space flight, spanning roughly from 1945 to 1985-a time when the "sound" and "heat" barriers were broken, men walked on the Moon, and space probes began journeys that have now taken them beyond the solar system. The author was not a well-known figure during these exciting years, but he had meaningful encounters with some of those who were. Along with his colleagues, he played a key role in overcoming several challenges facing military air and space flight.The book also addresses the remaining barriers that stand in the way of our next major steps in air and space exploration. It presents examples of materials, energy systems, propulsion technologies, and flight systems that may be required to overcome these obstacles.Finally, the possibility of reaching-or even exceeding-the speed of light is explored, along with the author's perspective on the future of spaceflight and the potential for humanity to one day reach the stars.