Front Matter -- Preface -- Acknowledgments -- Contents -- Executive Summary -- 1 Issues and Considerations in the Assessment of Mission Size Trade-offs in the Earth and Space Sciences -- 2 Science Priorities and NASA Mission Plans -- 3 Summary and Recommendations -- A Letter of Request from NASA to the Space Studies Board -- B Statement of Task -- C Information Sought from Space Studies Board Discipline Committees -- D Meeting Agenda -- E Material Provided by Space Studies Board Discipline Committees -- F Acronyms and Abbreviations -- G Biographies of Committee Members.