of exciting intellectual challenges as well as societal relevance that draws the best and brightest students to the field, and this is critical to bolstering Earth science expertise in the population throughout the upcoming century.

A decade ago, the Basic Research Opportunities in Earth Science (BROES) report (NRC, 2001) outlined many examples of the synergism between a diverse, healthy basic research program and the advances of directed research efforts. That report presented examples of how advances in basic Earth science research areas intersect with five national imperatives and, as exemplified in Chapter 2 of this report, significant progress has been made toward each of these imperatives:

1.  Discovery, use, and conservation of natural resources continue to benefit from improved theory, data collection strategies, and methods developed in seismology, volcanology, magnetotellurics, geodesy, low-temperature geochemistry, geomorphology, and hydrology.

2.  Characterization and mitigation of natural hazards are directly impacted by basic research on earthquake faulting, hydrology, geochemistry, geodesy, geomorphology, and surface evolution.

3.  Geotechnical support of commercial and infrastructure development is strongly influenced by basic understanding of soil science, geomorphology, hydrology, seismology, and geodynamics.

4.  Stewardship of the environment is informed by historical climate change, separation of secular and anthropogenic contributions, soil science, volatile fluxes, geomorphology, and coastal science.

5.  Terrestrial surveillance for global security and national defense is advanced by basic research on Earth’s interior; global geosystems; global seismic, geodetic, and meteorological measurements; and other remote-sensing approaches.

Further documentation of the role of basic science in contributing to these national priorities is provided by the many research community strategic plans and research summaries (see Appendix A), and full details are not repeated here. The emphasis of this report is on identifying key areas of research opportunity that can build on the foundations of sustained core subdisciplinary research to make major advances in the Earth sciences in the next decade.

THE EARLY EARTH

A large number of critical processes and events formed Earth and guided its evolution to the present state. Unique to the Hadean Eon (the first 500 million years of Earth history) were the formation of planetesimals, planetary embryos, and the moon; the mineralogy, petrology, and dynamics of magma oceans; the dynamics and chemistry of core formation and initiation of the geodynamo; formation of the earliest crust, atmosphere, and ocean; acquisition of surface volatiles; transition from an impact-dominated surface to one shaped by plate tectonics; and the terrestrial consequences of the young sun. The 2008 NRC report Origin and Evolution of Earth identified the question “What happened during Earth’s dark age?” as a research grand challenge in the Earth sciences.

There are multiple avenues for new insights into the early Earth. A primary objective is to increase the inventory of early Earth samples by expanding the search for yet older rocks and minerals. Still another is to quantify early Earth history using novel combinations of isotope systems and new micro-and nanotechnologies. Sustained progress will require synthesizing geochronology and geochemical data with dynamical models that bridge the gap between planet formation and plate tectonics by incorporating the highly energetic conditions of the early Earth. Advances in high-performance computing hardware and parallel advances in software will make it possible to model processes such as giant impacts, magma oceans, crust, and core formation using realistic Earth parameters. The challenges of early Earth history argue for strengthening links with astronomy and astrophysics, planetary science, molecular biology, and biochemistry.

Finding 1: Organizing the diverse expertise within EAR and beyond would address major questions about the early Earth. Advances can come from collaborations with astronomy, astrophysics, planetary science, exoplanet detection and characterization, and astrobiology. EAR coordination with the research efforts of the National Aeronautics and Space Administration (NASA) is particularly relevant, because NASA



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