We live in a time of extraordinary discovery and progress in astronomy and astrophysics. The next decade will transform our understanding of the universe and humanity's place in it. Every decade the U.S. agencies that provide primary federal funding for astronomy and astrophysics request a survey to assess the status of, and opportunities for the Nation's efforts to forward our understanding of the cosmos. Pathways to Discovery in Astronomy and Astrophysics for the 2020s identifies the most compelling science goals and presents an ambitious program of ground- and space-based activities for future investment in the next decade and beyond. The decadal survey identifies three important science themes for the next decade aimed at investigating Earth-like extrasolar planets, the most energetic processes in the universe, and the evolution of galaxies. The Astro2020 report also recommends critical near-term actions to support the foundations of the profession as well as the technologies and tools needed to carry out the science. Table of Contents Front Matter Summary 1 Pathways to Discovery: From Foundations to Frontiers 2 A New Cosmic Perspective 3 The Profession and Its Societal Impacts: Gateways to Science, Pathways to Diversity, Equity, and Sustainability 4 Optimizing the Science: Foundations 5 Evaluating and Balancing the Operational Portfolio 6 Technology Foundations and Small and Medium Scale Sustaining Programs 7 Realizing the Opportunities: Medium- and Large-Scale Programs Appendixes Appendix A: Statement of Task and Panel Descriptions Appendix B: Report of the Panel on Compact Objects and Energetic Phenomena Appendix C: Report of the Panel on Cosmology Appendix D: Report of the Panel on Galaxies Appendix E: Report of the Panel on Exoplanets, Astrobiology, and the Solar System Appendix F: Report of the Panel on the Interstellar Medium and Star and Planet Formation Appendix G: Report of the Panel on Stars, the Sun, and Stellar Populations Appendix H: Report of the Panel on an Enabling Foundation for Research Appendix I: Report of the Panel on Electromagnetic Observations from Space 1 Appendix J: Report of the Panel on Electromagnetic Observations from Space 2 Appendix K: Report of the Panel on Optical and Infrared Observations from the Ground Appendix L: Report of the Panel on Particle Astrophysics and Gravitation Appendix M: Report of the Panel on Radio, Millimeter, and Submillimeter Observations from the Ground Appendix N: Report of the Panel on the State of the Profession and Societal Impacts Appendix O: Independent Technical, Risk, and Cost Evaluation Appendix P: Acronyms Appendix Q: Committee and Panel Biographical Information

The next decade of planetary science and astrobiology holds tremendous promise. New research will expand our understanding of our solar system's origins, how planets form and evolve, under what conditions life can survive, and where to find potentially habitable environments in our solar system and beyond. Origins, Worlds, and Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032 highlights key science questions, identifies priority missions, and presents a comprehensive research strategy that includes both planetary defense and human exploration. This report also recommends ways to support the profession as well as the technologies and infrastructure needed to carry out the science. Table of Contents Front Matter Summary 1 Introduction to Planetary Science, Astrobiology, and Planetary Defense 2 Tour of the Solar System: A Transformative Decade of Exploration 3 Priority Science Questions 4 Question 1: Evolution of the Protoplanetary Disk 5 Question 2: Accretion in the Outer Solar System 6 Question 3: Origin of Earth and Inner Solar System Bodies 7 Question 4: Impacts and Dynamics 8 Question 5: Solid Body Interiors and Surfaces 9 Question 6: Solid Body Atmospheres, Exospheres, Magnetospheres, and Climate Evolution 10 Question 7: Giant Planet Structure and Evolution 11 Question 8: Circumplanetary Systems 12 Question 9: Insights from Terrestrial Life 13 Question 10: Dynamic Habitability 14 Question 11: Search for Life Elsewhere 15 Question 12: Exoplanets 16 State of the Profession 17 Research and Analysis 18 Planetary Defense: Defending Earth through Applied Planetary Science 19 Human Exploration 20 Infrastructure for Planetary Science and Exploration 21 Technology 22 Recommended Program: 2023-2032 23 The Future Appendixes Appendix A: Letter of Request, Statement of Task, and Other Guidance Appendix B: White Papers Received Appendix C: Technical Risk and Cost Evaluation of Priority Missions Appendix D: Missions Studied But Not Sent for TRACE Appendix E: Panel Missions Not Selected for Additional Study Appendix F: Glossary and Acronyms Appendix G: Biographies of Committee Members and Staff

The search for life in the solar system and beyond has to date been governed by a model based on what we know about life on Earth (terran life). Most of NASA's mission planning is focused on locations where liquid water is possible and emphasizes searches for structures that resemble cells in terran organisms. It is possible, however, that life exists that is based on chemical reactions that do not involve carbon compounds, that occurs in solvents other than water, or that involves oxidation-reduction reactions without oxygen gas. To assist NASA incorporate this possibility in its efforts to search for life, the NRC was asked to carry out a study to evaluate whether nonstandard biochemistry might support life in solar system and conceivable extrasolar environments, and to define areas to guide research in this area. This book presents an exploration of a limited set of hypothetical chemistries of life, a review of current knowledge concerning key questions or hypotheses about nonterran life, and suggestions for future research. Table of Contents Front Matter Executive Summary 1 Introduction 2 A Sketch of the Chemistry Behind Known Carbon-based Life on Earth 3 Pushing the Boundaries of Life 4 Alternatives to Terran Biochemistry in Water 5 Origin of Life 6 Why Water? Toward More Exotic Habitats 7 Life Detection and Biomarkers 8 Conclusions and Recommendations Appendix A Glossary Appendix B Biographies of Committee Members and Staff

In 2000, the nation's next-generation National Polar-orbiting Operational Environmental Satellite System (NPOESS) program anticipated purchasing six satellites for $6.5 billion, with a first launch in 2008. By November 2005, however, it became apparent that NPOESS would overrun its cost estimates by at least 25 percent. In June 2006, the planned acquisition of six spacecraft was reduced to four, the launch of the first spacecraft was delayed until 2013, and several sensors were canceled or descoped in capability. To examine the impacts of these changes, particularly those associated with climate research, and ways to mitigate those impacts, NASA and NOAA asked the NRC to add this task to its ongoing "decadal survey," Earth Science and Applications from Space. The sponsors and the NRC agreed to address this task separately and to base its analysis on a major workshop. This book presents summaries of discussions at the workshop, which included sessions on the measurements and sensors originally planned for NPOESS and GOES-R; generation of climate data records; mitigation options, including the role of international partners; and cross-cutting issues. Table of Contents Front Matter Summary 1 Implications of the NPOESS Nunn-McCurdy Certification and the Descoping of GOES-R 2 Summary of the Workshop Sessions 3 Cross-Cutting Issues Appendix A: Statement of Task Appendix B: Workshop Agenda Appendix C: Mitigation Approaches Presented by NASA and NOAA at the Workshop Appendix D: Abbreviations and Acronyms Appendix E: Biographical Sketches of Panel Members

Numerous countries and regions now have very active space programs, and the number is increasing. These maturing capabilities around the world create a plethora of potential partners for cooperative space endeavors, while at the same time heightening competitiveness in the international space arena. This book summarizes a public workshop held in November 2008 for the purpose of reviewing past and present cooperation, coordination, and competition mechanisms for space and Earth science research and space exploration; identifying significant lessons learned; and discussing how those lessons could best be applied in the future, particularly in the areas of cooperation and collaboration. Presentations and initial discussion focused on past and present experiences in international cooperation and competition to identify "lessons learned." Those lessons learned were then used as the starting point for subsequent discussions on the most effective ways for structuring future cooperation or coordination in space and Earth science research and space exploration. The goal of the workshop was not to develop a specific model for future cooperation or coordination, but rather to explore the advantages and disadvantages of various approaches and stimulate further deliberation on this important topic.