Market: Researchers in solid earth geophysics and planetary geophysics. This book is a record of the one-day symposium organized by the Space Policy Institute of the George Washington University's Elliot School of International Affairs, in cooperation with NASA's Office of Mission to Planet Earth. The meeting provided an authoritative overview of the progress that had been made to date in the study of Earth from space and identified the steps being taken to ensure that future space-based Earth observation missions make as great a scientific contribution as possible in support of the Earth system science concept.