Earth science is evolving into Earth system science, changing from a discipline-specific premise to an interdisciplinary endeavor. Increased awareness of human dependence and impact upon the environment has made global change research one of the most pressing policy issues facing decision makers today. This book presents an overview of past, present, and future satellite missions and programs and their sensor complements. An effort has been made to show to some extent the scale and nature of existingnational and international activities and operations in this context. Text and illustrations are intended as a guide and roadmap to everyone interested in the wide field of Earth observation. In particular, the book may serve as a reference, or give reasonable inputs, on the following subjects: Programmatic planning on all levels, planning for the required infrastructure, exisiting and planned operational service provision, data utilization and exploitation.