This book was sponsored by the U.S. Air Force Academy Space Mission Analysis and Design Program with support from program offices at the Air Force Space and Missile Systems Center, the National Reconnaissance Office, the U. S. Department of Transportation, and organizations within the National Aeronautics and Space Administration. This book is a must-read for engineers in several disciplines, including program management, who have a need to understand contemporary issues associated with modeling and simulation for development and operation of space systems. The 22 chapters in this work are well suited collectively to enable readers to become familiar with present practices and future prospects in modeling and simulation in this important application area. The first portion of the book explores general issues in modeling and simulation, the essentials of obtaining an appropriate model and a computer simulation based on this model, and how simulation-based acquisition using these principles can yield space systems of major value. This is followed by several chapters that discuss a plethora of important subjects related to specific facets of importance for the space system life-cycle phases associated with the process for engineering these systems. The final chapter discusses likely futures in this area.