Navigation in Space by X-ray Pulsars will consist of two parts. One is on modeling of X-ray pulsar signals. The second part explains how X-ray pulsar signals can be used to solve the relative navigation problem. This book formulates the problem, proposes a recursive solution, and analyzes different aspects of the navigation system. This book will be a comprehensive source for researchers. It provides new research results on signal processing techniques needed for X-ray pulsar based navigation in deep space.