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Science in NASA’s Vision for Space Exploration Appendixes

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Science in NASA’s Vision for Space Exploration A Major Scientific Questions Defined by the Decadal Survey Reports ASTRONOMY AND ASTROPHYSICS1 Defining questions for astronomy and astrophysics: How were the universe and its constituent galaxies, stars, and planets formed? How did they evolve? What will their destiny be? Strategy to achieve that goal: Survey the universe and its constituents (galaxies and their evolution, stars in formation stage, interstellar and intergalactic matter, dark matter and dark energy). Use the universe as a unique laboratory for understanding physics. Search for life beyond Earth and, if it is found, determine its nature and distribution. Develop a conceptual framework accounting for all observations made. Key problems ripe for advance in this decade: Determine large-scale properties of the universe: its age, the nature (amount and distribution) of the matter and energy that make it up, and the history of its expansion. Study the dawn of the modern universe, when the first stars and galaxies formed. Understand the formation and evolution of black holes of all sizes. Study the formation of stars and their and planetary systems, and the birth and evolution of giant and terrestrial planets. Understand how the astronomical environment affects Earth. THE UNIVERSE AND THE NATURE OF MATTER, SPACE, AND TIME2 What is the dark matter? What is the nature of the dark energy? How did the universe begin? Did Einstein have the last word on gravity? What are the masses of the neutrinos, and how have they shaped the evolution of the universe? How do cosmic accelerators work and what are they accelerating? Are protons unstable? Are there new states of matter at exceedingly high density and temperature? Are there additional space-time dimensions? How were the elements from iron to uranium made? Is a new theory of matter and light needed at the highest energies? 1   National Research Council, Astronomy and Astrophysics in the New Millennium, National Academy Press, Washington, D.C., 2000. 2   National Research Council, Connecting Quarks with the Cosmos: Eleven Science Questions for the New Century, National Academies Press, Washington, D.C., 2003.

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Science in NASA’s Vision for Space Exploration SOLAR SYSTEM EXPLORATION3 First Billion Years of Solar System History (planet formation/emergence of life) What processes marked the initial stages of planet and satellite formation? What was the nature of Jupiter’s formation, and how different was it from that of Neptune, Uranus, and Saturn? How did the impactor flux decay in the early solar system, and how did this affect the timing of the emergence of life on Earth? Volatiles and Organics: The Stuff of Life (organic materials, water, etc.) What is the history of volatile compounds, especially water, in the solar system? What is the nature of organic material in the solar system and how has it evolved? What global mechanisms affect the evolution of volatiles on planets? The Origin and Evolution of Habitable Worlds What planetary processes generate and sustain habitable worlds, and where are the habitable zones in the solar system? Does (or did) life exist beyond Earth? Why have the terrestrial planets differed so dramatically in their evolution? What hazards do solar system objects present to Earth’s biosphere? Processes: How Planets Work How do processes that shape the character of planets operate and interact? What does the solar system tell us about the development of extrasolar planetary systems, and vice versa? SOLAR AND SPACE PHYSICS4 Understanding the structure and dynamics of the Sun’s interior, the generation of solar magnetic fields, the origin of the solar cycle, the causes of solar activity, and the structure and dynamics of the corona. Why does solar activity vary in a regular 11-year cycle? Why is the solar corona several thousand times hotter than its underlying visible surface, and how is the supersonic solar wind produced? Understanding heliospheric structure, the distribution of magnetic fields and matter throughout the solar system, and the interaction of the solar atmosphere with the local interstellar medium. What is the nature of the interstellar medium, and how does the heliosphere interact with it? How do energetic solar events propagate through the heliosphere? Understanding the space environments of Earth and other solar system bodies and their dynamical response to external and internal influences. How does Earth’s global space environment respond to solar variations? What are the roles of planetary ionospheres, planetary rotation, and internal 3   National Research Council, New Frontiers in the Solar System: An Integrated Exploration Strategy, National Academy Press, Washington, D.C., 2002. 4   National Research Council, The Sun to the Earth—and Beyond: A Decadal Research Strategy in Solar and Space Physics, National Academy Press, Washington, D.C., 2002.

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Science in NASA’s Vision for Space Exploration plasma sources in the transfer of energy among planetary ionospheres and magnetospheres and the solar wind? Understanding the basic physical principles manifest in processes observed in solar and space plasmas. How is magnetic field energy converted to heat and particle kinetic energy in magnetic reconnection events? Developing near-real-time predictive capability for understanding and quantifying the impact on human activities of dynamical processes at the Sun, in the interplanetary medium, and in Earth’s magnetosphere. What is the probability of occurrence of specific types of space weather phenomena over periods from hours to days?