Popular culture is flourishing again, with a renewed interest in the ET and UFO phenomena. We are inundated with films, TV programmes and books, plus many conspiracy theories, dealing with the phenomena. Governments and security agencies are denying any interest in the issue, yet releasing masses of documents (mostly unreadable) after being compelled to, by the Freedom of Information Act. Such speculation and documentation in ancient writings suggests that an unearthly presence has been in Earth-space for many generations. The question of this situation must reach a culminating point sometime in the near future. This book is concerned with the cultural shock and social disorientation that would obviously occur with a sudden appearance en-mass of an alien race finally revealing themselves to humanity and how the people of Earth would react.

NASA's Earth Science Division (ESD) conducts a wide range of satellite and suborbital missions to observe Earth's land surface and interior, biosphere, atmosphere, cryosphere, and oceans as part of a program to improve understanding of Earth as an integrated system. Earth observations provide the foundation for critical scientific advances and environmental data products derived from these observations are used in resource management and for an extraordinary range of societal applications including weather forecasts, climate projections, sea level change, water management, disease early warning, agricultural production, and the response to natural disasters. As the complexity of societal infrastructure and its vulnerability to environmental disruption increases, the demands for deeper scientific insights and more actionable information continue to rise. To serve these demands, NASA's ESD is challenged with optimizing the partitioning of its finite resources among measurements intended for exploring new science frontiers, carefully characterizing long-term changes in the Earth system, and supporting ongoing societal applications. This challenge is most acute in the decisions the Division makes between supporting measurement continuity of data streams that are critical components of Earth science research programs and the development of new measurement capabilities. This report seeks to establish a more quantitative understanding of the need for measurement continuity and the consequences of measurement gaps. Continuity of NASA's Earth's Observations presents a framework to assist NASA's ESD in their determinations of when a measurement or dataset should be collected for durations longer than the typical lifetimes of single satellite missions. Table of Contents Front Matter Summary 1 Introduction 2 Measurement Continuity 3 A Decision Framework for NASA Earth Science Continuity Measurements 4 Applying the Framework to Continuity Measurements Appendixes Appendix A: Statement of Task Appendix B: Quality Metric Examples Using Current Climate Data Records Appendix C: Full Framework Example: Narrowing Uncertainty in Climate Sensitivity Appendix D: Full Framework Example: Determining Sea Level Rise and Its Acceleration Appendix E: Full Framework Example: Determining the Change in Ocean Heat Storage Appendix F: Full Framework Example: Determining Ice Sheet Mass Balance Appendix G: Full Framework Example: Global Land Carbon Sinks Appendix H: Committee and Staff Biographical Information Appendix I: Acronyms and Abbreviations