Book excerpt: This book describes a new type of rocket science needed to create low-cost, reliable, responsive space transportation. You don't have to be a rocket scientist to understand the issues explored within this book. The text is beyond the current state-of-the-art engineering of modern launch vehicles, going into a scientific investigation that opens the door to true design optimization. The purpose of this work is to enable the reader to understand how low-cost space transportation is practical, and why it has been so hard to achieve.