Utilization of space, what for? This book attempts to answer this question! With this volume we intend to provide a single reference for the broad field of space utilization. Of all the books we know, this is the first to cover all aspects of scientific and application oriented activities in space, even though with limits. We have attempted to document the current state of the art and open at the same time a perspective towards the future. We also want to bridge the gap between the many popular books dealing with space, and academic te- books on specific research fields in space science, applications, or technology. The book addresses a professional readership, while still offering much information to interested laymen. It should well serve students of physics, geodesy, informatics, mechanical, electrical or aerospace engineering. It should give scientists at universities and research institutions an overview of the extensive opportunities offered by space investigations, and industrial engineers and managers additional insights into the commercial potential of space. It should also help decision makers in agencies, governments, and industry to understand better the multidisciplinary interrelationships between utilization aspects and space infrastructure. Our co-authors are amongst the world’s most distinguished leaders in their fields. Their respective areas of - search are presented by many illustrations and focus on the central messages rather than attempting to be exha- tive. Each chapter lists references for further reading, highlighting original publications, the most relevant te- books, and major internet resources.