WorldWideScience

Sample records for early earth summary

  1. The Earth's early evolution.

    Science.gov (United States)

    Bowring, S A; Housh, T

    1995-09-15

    The Archean crust contains direct geochemical information of the Earth's early planetary differentiation. A major outstanding question in the Earth sciences is whether the volume of continental crust today represents nearly all that formed over Earth's history or whether its rates of creation and destruction have been approximately balanced since the Archean. Analysis of neodymium isotopic data from the oldest remnants of Archean crust suggests that crustal recycling is important and that preserved continental crust comprises fragments of crust that escaped recycling. Furthermore, the data suggest that the isotopic evolution of Earth's mantle reflects progressive eradication of primordial heterogeneities related to early differentiation.

  2. Earth's early biosphere

    Science.gov (United States)

    Des Marais, D. J.

    1998-01-01

    Understanding our own early biosphere is essential to our search for life elsewhere, because life arose on Earth very early and rocky planets shared similar early histories. The biosphere arose before 3.8 Ga ago, was exclusively unicellular and was dominated by hyperthermophiles that utilized chemical sources of energy and employed a range of metabolic pathways for CO2 assimilation. Photosynthesis also arose very early. Oxygenic photosynthesis arose later but still prior to 2.7 Ga. The transition toward the modern global environment was paced by a decline in volcanic and hydrothermal activity. These developments allowed atmospheric O2 levels to increase. The O2 increase created new niches for aerobic life, most notably the more advanced Eukarya that eventually spawned the megascopic fauna and flora of our modern biosphere.

  3. Summary of the Geocarto International Special Issue on "NASA Earth Science Satellite Data for Applications to Public Health" to be Published in Early 2014

    Science.gov (United States)

    Quattrochi, Dale A.

    2013-01-01

    At the 2011 Applied Science Public Health review held in Santa Fe, NM, it was announced that Dr. Dale Quattrochi from the NASA Marshall Space Flight Center, John Haynes, Program Manager for the Applied Sciences Public Health program at NASA Headquarters, and Sue Estes, Deputy Program Manager for the NASA Applied Sciences Public Health Program located at the Universities Space Research Association (USRA) at the National Space Science and Technology Center (NSSTC) in Huntsville, AL, would edit a special issue of the journal Geocarto International on "NASA Earth Science Satellite Data for Applications to Public Health". This issue would be focused on compiling research papers that use NASA Earth Science satellite data for applications to public health. NASA's Public Health Program concentrates on advancing the realization of societal and economic benefits from NASA Earth Science in the areas of infectious disease, emergency preparedness and response, and environmental health (e.g., air quality). This application area as a focus of the NASA Applied Sciences program, has engaged public health institutions and officials with research scientists in exploring new applications of Earth Science satellite data as an integral part of public health decision- and policy-making at the local, state and federal levels. Of interest to this special issue are papers submitted on are topics such as epidemiologic surveillance in the areas of infectious disease, environmental health, and emergency response and preparedness, national and international activities to improve skills, share data and applications, and broaden the range of users who apply Earth Science satellite data in public health decisions, or related focus areas.. This special issue has now been completed and will be published n early 2014. This talk will present an overview of the papers that will be published in this special Geocarto International issue.

  4. Helium in Earth's early core

    Science.gov (United States)

    Bouhifd, M. A.; Jephcoat, Andrew P.; Heber, Veronika S.; Kelley, Simon P.

    2013-11-01

    The observed escape of the primordial helium isotope, 3He, from the Earth's interior indicates that primordial helium survived the energetic process of planetary accretion and has been trapped within the Earth to the present day. Two distinct reservoirs in the Earth's interior have been invoked to account for variations in the 3He/4He ratio observed at the surface in ocean basalts: a conventional depleted mantle source and a deep, still enigmatic, source that must have been isolated from processing throughout Earth history. The Earth's iron-based core has not been considered a potential helium source because partitioning of helium into metal liquid has been assumed to be negligible. Here we determine helium partitioning in experiments between molten silicates and iron-rich metal liquids at conditions up to 16GPa and 3,000K. Analyses of the samples by ultraviolet laser ablation mass spectrometry yield metal-silicate helium partition coefficients that range between 4.7×10-3 and 1.7×10-2 and suggest that significant quantities of helium may reside in the core. Based on estimated concentrations of primordial helium, we conclude that the early core could have incorporated enough helium to supply deep-rooted plumes enriched in 3He throughout the age of the Earth.

  5. Mission to Very Early Earth

    Energy Technology Data Exchange (ETDEWEB)

    Hutcheon, I D; Weber, P K; Fallon, S J; Smith, J B; Aleon, J; Ryerson, F J; Harrison, T M; Cavosie, A J; Valley, J W

    2007-03-13

    The Hadean Earth is often viewed as an inhospitable and, perhaps, unlikely setting for the rise of primordial life. However, carbonaceous materials supplied by accreting meteorites and sources of chemical energy similar to those fueling life around modern deep-sea volcanic vents would have been present in abundance. More questionable are two other essential ingredients for life - liquid water and clement temperatures. Did the Hadean Earth possess a hydrosphere and temperate climate compatible with the initiation of biologic activity? If so, the popular model of an excessively hot planetary surface characterized by a basaltic crust, devoid of continental material is invalid. Similarly, establishment of an Hadean hydrosphere prior to the cessation of heavy asteroid bombardment may mean that primitive life could have evolved and then been extinguished, only to rise again. The most effective means of determining the environmental conditions on this young planet is through geochemical analysis of samples retrieved from the Early Earth. While rocks older than 4 billion years (4 Ga) have not been found, individual zircon grains, the detritus of rocks long since eroded away, have been identified with ages as old as 4.4 Ga - only {approx}160 million years younger than the Earth itself. If we can use the geochemical information contained in these unique samples to infer the nature of their source rocks and the processes that formed them, we can place constraints on the conditions prevailing at the Earth's surface shortly after formation. This project utilizes a combined analytical and experimental approach to gather the necessary geochemical data to determine the parameters required to relate the zircons to their parent materials. Mission to Early Earth involves dating, isotopic and chemical analyses of mineral and melt inclusions within zircons and of the zircons themselves. The major experimental activity at LLNL focused on the partitioning of trace elements between

  6. Early Earth(s) Across Time and Space

    Science.gov (United States)

    Mojzsis, S.

    2014-04-01

    The geochemical and cosmochemical record of our solar system is the baseline for exploring the question: "when could life appear on a world similar to our own?" Data arising from direct analysis of the oldest terrestrial rocks and minerals from the first 500 Myr of Earth history - termed the Hadean Eon - inform us about the timing for the establishment of a habitable silicate world. Liquid water is the key medium for life. The origin of water, and its interaction with the crust as revealed in the geologic record, guides our exploration for a cosmochemically Earth-like planets. From the time of primary planetary accretion to the start of the continuous rock record on Earth at ca. 3850 million years ago, our planet experienced a waning bolide flux that partially or entirely wiped out surface rocks, vaporized oceans, and created transient serpentinizing atmospheres. Arguably, "Early Earths" across the galaxy may start off as ice planets due to feeble insolation from their young stars, occasionally punctuated by steam atmospheres generated by cataclysmic impacts. Alternatively, early global environments conducive to life spanned from a benign surface zone to deep into crustal rocks and sediments. In some scenarios, nascent biospheres benefit from the exogenous delivery of essential bio-elements via leftovers of accretion, and the subsequent establishment of planetary-scale hydrothermal systems. If what is now known about the early dynamical regime of the Earth serves as any measure of the potential habitability of worlds across space and time, several key boundary conditions emerge. These are: (i) availability and long-term stability of liquid water; (ii) presence of energy resources; (iii) accessibility of organic raw materials; (iv) adequate inventory of radioisotopes to drive internal heating; (v) gross compositional parameters such as mantle/core mass ratio, and (vi) P-T conditions at or near the surface suitable for sustaining biological activity. Life could

  7. Earth Sciences Division Research Summaries 2006-2007

    Energy Technology Data Exchange (ETDEWEB)

    DePaolo, Donald; DePaolo, Donald

    2008-07-21

    , climate systems, and environmental engineering. Building on this scientific foundation, we also perform applied earth science research and technology development to support DOE in a number of its program areas. We currently organize our efforts in the following Division Programs: Fundamental and Exploratory Research--fundamental research in geochemistry, geophysics, and hydrology to provide a basis for new and improved energy and environmental technologies; Climate and Carbon Sciences--carbon cycling in the terrestrial biosphere and oceans, and global and regional climate modeling, are the cornerstones of a major developing divisional research thrust related to understanding and mitigating the effects of increased greenhouse gas concentrations in the atmosphere; Energy Resources--collaborative projects with industry to develop or improve technologies for the exploration and production of oil, gas, and geothermal reservoirs, and for the development of bioenergy; Environmental Remediation and Water Resources--innovative technologies for locating, containing, and remediating metals, radionuclides, chlorinated solvents, and energy-related contaminants in soils and groundwaters; Geologic Carbon Sequestration--development and testing of methods for introducing carbon dioxide to subsurface geologic reservoirs, and predicting and monitoring its subsequent migration; and Nuclear Waste and Energy--theoretical, experimental, and simulation studies of the unsaturated zone at Yucca Mountain, Nevada. These programs draw from each of ESD's disciplinary departments: Climate Science, Ecology, Geochemistry, Geophysics, and Hydrogeology. Short descriptions of these departments are provided as introductory material. In this document, we present summaries of selected current research projects. While it is not a complete accounting, the projects described here are representative of the nature and breadth of the ESD research effort. We are proud of our scientific accomplishments and we

  8. Earth Sciences Division Research Summaries 2006-2007

    Energy Technology Data Exchange (ETDEWEB)

    DePaolo, Donald; DePaolo, Donald

    2008-07-21

    , climate systems, and environmental engineering. Building on this scientific foundation, we also perform applied earth science research and technology development to support DOE in a number of its program areas. We currently organize our efforts in the following Division Programs: Fundamental and Exploratory Research--fundamental research in geochemistry, geophysics, and hydrology to provide a basis for new and improved energy and environmental technologies; Climate and Carbon Sciences--carbon cycling in the terrestrial biosphere and oceans, and global and regional climate modeling, are the cornerstones of a major developing divisional research thrust related to understanding and mitigating the effects of increased greenhouse gas concentrations in the atmosphere; Energy Resources--collaborative projects with industry to develop or improve technologies for the exploration and production of oil, gas, and geothermal reservoirs, and for the development of bioenergy; Environmental Remediation and Water Resources--innovative technologies for locating, containing, and remediating metals, radionuclides, chlorinated solvents, and energy-related contaminants in soils and groundwaters; Geologic Carbon Sequestration--development and testing of methods for introducing carbon dioxide to subsurface geologic reservoirs, and predicting and monitoring its subsequent migration; and Nuclear Waste and Energy--theoretical, experimental, and simulation studies of the unsaturated zone at Yucca Mountain, Nevada. These programs draw from each of ESD's disciplinary departments: Climate Science, Ecology, Geochemistry, Geophysics, and Hydrogeology. Short descriptions of these departments are provided as introductory material. In this document, we present summaries of selected current research projects. While it is not a complete accounting, the projects described here are representative of the nature and breadth of the ESD research effort. We are proud of our scientific accomplishments and we

  9. Earth Sciences Division Research Summaries 2002-2003

    Energy Technology Data Exchange (ETDEWEB)

    Bodvarsson, G.S.

    2003-11-01

    Research in earth and atmospheric sciences is becoming increasingly important in light of the energy, climate change, and environmental issues facing the United States and the world. The development of new energy resources other than hydrocarbons and the safe disposal of nuclear waste and greenhouse gases (such as carbon dioxide and methane) are critical to the future energy needs and environmental safety of this planet. In addition, the cleanup of many contaminated sites in the U.S., along with the preservation and management of our water supply, remain key challenges for us as well as future generations. Addressing these energy, climate change, and environmental issues requires the timely integration of earth sciences' disciplines (such as geology, hydrology, oceanography, climatology, geophysics, geochemistry, geomechanics, ecology, and environmental sciences). This integration will involve focusing on fundamental crosscutting concerns that are common to many of these issues. A primary focus will be the characterization, imaging, and manipulation of fluids in the earth. Such capabilities are critical to many DOE applications, from environmental restoration to energy extraction and optimization. The Earth Sciences Division (ESD) of the Ernest Orlando Lawrence Berkeley National Laboratory (Berkeley Lab) is currently addressing many of the key technical issues described above. In this document, we present summaries of many of our current research projects. While it is not a complete accounting, it is representative of the nature and breadth of our research effort. We are proud of our scientific efforts, and we hope that you will find our research useful and exciting. Any comments on our research are appreciated and can be sent to me personally. This report is divided into five sections that correspond to the major research programs in the Earth Sciences Division: (1) Fundamental and Exploratory Research; (2) Nuclear Waste; (3) Energy Resources; (4

  10. Teaching about the Early Earth: Evolution of Tectonics, Life, and the Early Atmosphere

    Science.gov (United States)

    Mogk, D. W.; Manduca, C. A.; Kirk, K.; Williams, M. L.

    2007-12-01

    developed a collection of teaching strategies to begin to address the challenge of integrating new scientific advances with effective instructional practices with an emphasis on data analysis and critical review of evidence. The workshop webpage includes the workshop program with links to all presentations and discussion summaries, a collection of recommended readings about early Earth research, ideas for teaching about Early Earth, suggestions on how to teach uncertain science, and classroom activities.

  11. Warming the early Earth - CO2 reconsidered

    CERN Document Server

    Von Paris, P; Grenfell, L; Patzer, B; Hedelt, P; Stracke, B; Trautmann, T; Schreier, F

    2008-01-01

    Despite a fainter Sun, the surface of the early Earth was mostly ice-free. Proposed solutions to this so-called "faint young Sun problem" have usually involved higher amounts of greenhouse gases than present in the modern-day atmosphere. However, geological evidence seemed to indicate that the atmospheric CO2 concentrations during the Archaean and Proterozoic were far too low to keep the surface from freezing. With a radiative-convective model including new, updated thermal absorption coefficients, we found that the amount of CO2 necessary to obtain 273 K at the surface is reduced up to an order of magnitude compared to previous studies. For the late Archaean and early Proterozoic period of the Earth, we calculate that CO2 partial pressures of only about 2.9 mb are required to keep its surface from freezing which is compatible with the amount inferred from sediment studies. This conclusion was not significantly changed when we varied model parameters such as relative humidity or surface albedo, obtaining CO2 ...

  12. Prebiotic Phosphorylation Reactions on the Early Earth

    Directory of Open Access Journals (Sweden)

    Maheen Gull

    2014-07-01

    Full Text Available Phosphorus (P is an essential element for life. It occurs in living beings in the form of phosphate, which is ubiquitous in biochemistry, chiefly in the form of C-O-P (carbon, oxygen and phosphorus, C-P, or P-O-P linkages to form life. Within prebiotic chemistry, several key questions concerning phosphorus chemistry have developed: what were the most likely sources of P on the early Earth? How did it become incorporated into the biological world to form the P compounds that life employs today? Can meteorites be responsible for the delivery of P? What were the most likely solvents on the early Earth and out of those which are favorable for phosphorylation? Or, alternatively, were P compounds most likely produced in relatively dry environments? What were the most suitable temperature conditions for phosphorylation? A route to efficient formation of biological P compounds is still a question that challenges astrobiologists. This article discusses these important issues related to the origin of biological P compounds.

  13. International strategic minerals inventory summary report; rare-earth oxides

    Science.gov (United States)

    Jackson, W.D.; Christiansen, Grey

    1993-01-01

    Bastnaesite, monazite, and xenotime are currently the most important rare-earth minerals. Bastnaesite occurs as a primary mineral in carbonatites. Monazite and xenotime also can be found in primary deposits but are recovered principally from heavy-mineral placers that are mined for titanium or tin. Each of these minerals has a different composition of the 15 rare-earth elements. World resources of economically exploitable rare-earth oxides (REO) are estimated at 93.4 million metric tons in place, composed of 93 percent in primary deposits and 7 percent in placers. The average mineral composition is 83 percent bastnaesite, 13 percent monazite, and 4 percent of 10 other minerals. Annual global production is about 67,000 metric tons of which 41 percent is from placers and 59 percent is from primary deposits; mining methods consist of open pits (94 percent) and dredging (6 percent). This output could be doubled if the operations that do not currently recover rare earths would do so. Resources are more than sufficient to meet the demand for the predictable future. About 52 percent of the world's REO resources are located in China. Ranking of other countries is as follows: Namibia (22 percent), the United States (15 percent), Australia (6 percent), and India (3 percent); the remainder is in several other countries. Conversely, 38 percent of the production is in China, 33 percent in the United States, 12 percent in Australia, and 5 percent each in Malaysia and India. Several other countries, including Brazil, Canada, South Africa, Sri Lanka, and Thailand, make up the remainder. Markets for rare earths are mainly in the metallurgical, magnet, ceramic, electronic, chemical, and optical industries. Rare earths improve the physical and rolling properties of iron and steel and add corrosion resistance and strength to structural members at high temperatures. Samarium and neodymium are used in lightweight, powerful magnets for electric motors. Cerium and yttrium increase the

  14. Earth observations from space: History, promise, and reality. Executive summary

    Science.gov (United States)

    1995-01-01

    In this report the Committee on Earth Studies (CES), a standing committee of the Space Studies Board (SSB) within the National Research Council (NRC), reviews the recent history (nominally from 1981 to 1995) of the U.S. earth observations programs that serve civilian needs. The principal observations programs examined are those of NASA and the National Oceanic and Atmospheric Administration (NOAA). The Air Force' s Defense Meteorological Satellite Program (DMSP) is discussed, but only from the perspective of its relationship to civil needs and the planned merger with the NOAA polar-orbiting system. The report also reviews the interfaces between the earth observations satellite programs and the major national and international environmental monitoring and research programs. The monitoring and research programs discussed are the U.S. Global Change Research Program (USGCRP), the International Geosphere-Biosphere Program (IGBP), the World Climate Research Program (WCRP), related international scientific campaigns, and operational programs for the sharing and application of environmental data. The purpose of this report is to provide a broad historical review and commentary based on the views of the CES members, with particular emphasis on tracing the lengthy record of advisory committee recommendations. Any individual topic could be the subject of an extended report in its own right. Indeed, extensive further reviews are already under way to that end. If the CES has succeeded in the task it has undertaken. This report will serve as a useful starting point for any such more intensive study. The report is divided into eight chapters: ( I ) an introduction, (2) the evolution of the MTPE, (3) its relationship to the USGCRP, (4) applications of earth observations data, (5) the role that smaller satellites can play in research and operational remote sensing, (6) earth system modeling and information systems, (7) a number of associated activities that contribute to the MTPE

  15. Magma Oceans on Exoplanets and Early Earth

    Science.gov (United States)

    Elkins-Tanton, Linda

    2009-09-01

    Late, giant accretionary impacts likely form multiple magma oceans of some depth in young rocky planets. Models of magma ocean solidification that incorporate water, carbon, and other incompatible volatile elements in small amounts predict a range of first-order outcomes important to planetary evolution. First, initial planetary bulk composition and size determine the composition of the earliest degassed atmosphere. This early atmosphere appears in a rapid burst at the end of solidification, determined by the ability of nucleating bubbles to reach the surface. Larger planets will have briefer and more catastrophic atmospheric degassing during solidification of any magma ocean. Second, this early atmosphere is sufficiently insulating to keep the planetary surface hot for millions of years. Depending upon the atmospheric composition and temperature structure these hot young planets may be observable from Earth or from satellites. Third, small but significant quantities of volatiles remain in the planet's solid mantle, encouraging convection, plate tectonics, and later atmospheric degassing through volcanism. A critical outcome of magma ocean solidification is the development of a solid mantle density gradient with den-sity increasing with radius, which will flow to gravitational stability. Shallow, dense, damp material will carry its water content as it sinks into the perovskite stability zone and transforms into perovskite. Even in models with very low initial water contents, a large fraction of the sinking upper mantle material will be forced to dewater as it crosses the boundary into the relatively dry lower mantle, leaving its water behind in a rapid flux as it sinks. This water ad-dition could initiate or speed convection in planets in which perovskite is stable, that is, planets larger than Mars.

  16. The early Earth atmosphere and early life catalysts.

    Science.gov (United States)

    Ramírez Jiménez, Sandra Ignacia

    2014-01-01

    Homochirality is a property of living systems on Earth. The time, the place, and the way in which it appeared are uncertain. In a prebiotic scenario two situations are of interest: either an initial small bias for handedness of some biomolecules arouse and progressed with life, or an initial slight excess led to the actual complete dominance of the known chiral molecules. A definitive answer can probably never be given, neither from the fields of physics and chemistry nor biology. Some arguments can be advanced to understand if homochirality is necessary for the initiation of a prebiotic homochiral polymer chemistry, if this homochirality is suggesting a unique origin of life, or if a chiral template such as a mineral surface is always required to result in an enantiomeric excess. A general description of the early Earth scenario will be presented in this chapter, followed by a general description of some clays, and their role as substrates to allow the concentration and amplification of some of the building blocks of life.

  17. Peptide synthesis in early earth hydrothermal systems

    Science.gov (United States)

    Lemke, K.H.; Rosenbauer, R.J.; Bird, D.K.

    2009-01-01

    We report here results from experiments and thermodynamic calculations that demonstrate a rapid, temperature-enhanced synthesis of oligopeptides from the condensation of aqueous glycine. Experiments were conducted in custom-made hydrothermal reactors, and organic compounds were characterized with ultraviolet-visible procedures. A comparison of peptide yields at 260??C with those obtained at more moderate temperatures (160??C) gives evidence of a significant (13 kJ ?? mol-1) exergonic shift. In contrast to previous hydrothermal studies, we demonstrate that peptide synthesis is favored in hydrothermal fluids and that rates of peptide hydrolysis are controlled by the stability of the parent amino acid, with a critical dependence on reactor surface composition. From our study, we predict that rapid recycling of product peptides from cool into near-supercritical fluids in mid-ocean ridge hydrothermal systems will enhance peptide chain elongation. It is anticipated that the abundant hydrothermal systems on early Earth could have provided a substantial source of biomolecules required for the origin of life. Astrobiology 9, 141-146. ?? 2009 Mary Ann Liebert, Inc. 2009.

  18. Siderophilic Cyanobacteria: Implications for Early Earth.

    Science.gov (United States)

    Brown, I. I.; Mummey, D.; Sarkisova, S.; Shen, G.; Bryant, D. A.; Lindsay, J.; Garrison, D.; McKay, D. S.

    2006-01-01

    Of all extant environs, iron-depositing hot springs (IDHS) may exhibit the greatest similarity to late Precambrian shallow warm oceans in regards to temperature, O2 gradients and dissolved iron and H2S concentrations. Despite the insights into the ecology, evolutionary biology, paleogeobiochemistry, and astrobiology examination of IDHS could potentially provide, very few studies dedicated to the physiology and diversity of cyanobacteria (CB) inhabiting IDHS have been conducted. Results. Here we describe the phylogeny, physiology, ultrastructure and biogeochemical activity of several recent CB isolates from two different greater Yellowstone area IDHS, LaDuke and Chocolate Pots. Phylogenetic analysis of 16S rRNA genes indicated that 6 of 12 new isolates examined couldn't be placed within established CB genera. Some of the isolates exhibited pronounced requirements for elevated iron concentrations, with maximum growth rates observed when 0.4-1 mM Fe(3+) was present in the media. In light of "typical" CB iron requirements, our results indicate that elevated iron likely represents a salient factor selecting for "siderophilicM CB species in IDHS. A universal feature of our new isolates is their ability to produce thick EPS layers in which iron accumulates resulting in the generation of well preserved signatures. In parallel, siderophilic CB show enhanced ability to etch the analogs of iron-rich lunar regolith minerals and impact glasses. Despite that iron deposition by CB is not well understood mechanistically, we recently obtained evidence that the PS I:PS II ratio is higher in one of our isolates than for other CB. Although still preliminary, this finding is in direct support of the Y. Cohen hypothesis that PSI can directly oxidize Fe(2+). Conclusion. Our results may have implications for factors driving CB evolutionary relationships and biogeochemical processes on early Earth and probably Mars.

  19. Identifying early Earth microfossils in unsilicified sediments

    Science.gov (United States)

    Javaux, Emmanuelle J.; Asael, Dan; Bekker, Andrey; Debaille, Vinciane; Derenne, Sylvie; Hofmann, Axel; Mattielli, Nadine; Poulton, Simon

    2013-04-01

    The search for life on the early Earth or beyond Earth requires the definition of biosignatures, or "indices of life". These traditionally include fossil molecules, isotopic fractionations, biosedimentary structures and morphological fossils interpreted as remnants of life preserved in rocks. This research focuses on traces of life preserved in unsilicified siliciclastic sediments. Indeed, these deposits preserve well sedimentary structures indicative of past aqueous environments and organic matter, including the original organic walls of microscopic organisms. They also do not form in hydrothermal conditions which may be source of abiotic organics. At our knowledge, the only reported occurrence of microfossils preserved in unsilicified Archean sediments is a population of large organic-walled vesicles discovered in shales and siltstones of the 3.2 Ga Moodies Group, South Africa. (Javaux et al, Nature 2010). These have been interpreted as microfossils based on petrographic and geochemical evidence for their endogenicity and syngeneity, their carbonaceous composition, cellular morphology and ultrastructure, occurrence in populations, taphonomic features of soft wall deformation, and the geological context plausible for life, as well as lack of abiotic explanation falsifying a biological origin. Demonstrating that carbonaceous objects from Archaean rocks are truly old and truly biological is the subject of considerable debate. Abiotic processes are known to produce organics and isotopic signatures similar to life. Spheroidal pseudofossils may form as self-assembling vesicles from abiotic CM, e.g. in prebiotic chemistry experiments (Shoztak et al, 2001), from meteoritic lipids (Deamer et al, 2006), or hydrothermal fluids (Akashi et al, 1996); by artifact of maceration; by migration of abiotic or biotic CM along microfractures (VanZuilen et al, 2007) or along mineral casts (Brasier et al, 2005), or around silica spheres formed in silica-saturated water (Jones and

  20. Mother Earth, Earth Mother: Gabriela Mistral as an Early Ecofeminist

    Science.gov (United States)

    Finzer, Erin

    2015-01-01

    Historians have noted that male bureaucrats and natural resource experts tended to dominate early twentieth-century national and hemispheric conservationist movements in Latin America, but a constellation of female activists, notable among them Gabriela Mistral, strengthened conservationism in the cultural sphere. Capitalizing on her leadership in…

  1. Thermospheric emissions of the early Earth

    Science.gov (United States)

    Bernard, D.; Barthélémy, M.; Gronoff, G.; Ménager, H.; Lilensten, J.

    2012-09-01

    The aim of this work is to examine the thermospheric emission of the Earth over its history. In this first step, we adapt a kinetic transport code developed for different planets of the Solar System to the first atmosphere of the Earth. We take into account the possible changes in the solar emission spectrum to compute the diurnal ionizations, excitations and dissociations. We deduce a thermospheric spectrum averaged over the planet. The effect of solar wind electron precipitation is also considered.

  2. Theia's Collision With The Early Earth - Dry Or Wet Moon?

    Science.gov (United States)

    Dvorak, R.; Loibnegger, B.; Burger, C.; Maindl, T. I.; Schäfer, C.

    2016-04-01

    Our study exist of three separated parts concerning the formation of the Moon due to a catastrophic collision of a Mars-sized body - often referred to as Theia - with the early Earth. The first one deals with planet-formation in the early Solar System, the second one with the dynamical evolution of the planets Venus, Earth, Mars, Jupiter, and Saturn and an additional planet (Theia) between Earth and Mars, and the third one with the proposed giant collision itself and its outcome concerning masses and water contents of the resulting bodies (or fragments), computed via Smoothed Particle Hydrodynamics (SPH) simulations.

  3. Accretion and early evolution of Earth

    DEFF Research Database (Denmark)

    Saji, Nikitha Susan

    -stage impacts had to play in determining the bulk composition as well as pace of the chemical dierentiation and internal dynamics of terrestrial planets - is preserved in the form of isotopic signatures in some of the oldest terrestrial and extraterrestrial samples available to us. A potential means to unravel...... this is by the application of Nd-isotope systematics as the coupled 146;147Sm - 143;142Nd decay system enables the study of chronology of planetary silicate mantles while the stable Nd-isotopes help track the origin and early transport of material. Deciphering this information, however, requires the analytical capability...... in solar system materials is found to be related to selective thermal processing of dust in the early nebula given the correlation observed for these eects with Fe-peak neutron-rich isotope anomalies, whose origin is attributed to distinct nucleosnythetic sites other than classical s-, r- or p...

  4. Organic chemistry in the ionosphere of the Early Earth

    Science.gov (United States)

    Carrasco, N.; Fleury, B.; Vettier, L.

    2015-10-01

    The emergence of life on the Early Earth during the Archean has required a prior complex organic chemistry providing the prerequisite bricks of life. The origin of the organic matter and its evolution on the early Earth is far from being understood. Several hypotheses are investigated, possibly complementary, which can be divided in two main categories: the endogenous and the exogenous sources. In this work we have been interested in the contribution of a specific endogenous source: the organic chemistry occurring in the ionosphere of the early Earth. At these high altitudes, the VUV contribution of the young sun was important, involving an efficient production of reactive species. Here we address the issue whether this chemistry can lead to the production of larger molecules with a prebiotic interest in spite of the competitive lysing effect of the harsh irradiation at these altitudes.

  5. The origin and early evolution of life on earth

    Science.gov (United States)

    Oro, J.; Miller, Stanley L.; Lazcano, Antonio

    1990-01-01

    Results of the studies that have provided insights into the cosmic and primitive earth environments are reviewed with emphasis on those environments in which life is thought to have originated. The evidence bearing on the antiquity of life on the earth and the prebiotic significance of organic compounds found in interstellar clouds and in primitive solar-system bodies such as comets, dark asteroids, and carbonaceous chondrites are assessed. The environmental models of the Hadean and early Archean earth are discussed, as well as the prebiotic formation of organic monomers and polymers essential to life. The processes that may have led to the appearance in the Archean of the first cells are considered, and possible effects of these processes on the early steps of biological evolution are analyzed. The significance of these results to the study of the distribution of life in the universe is evaluated.

  6. Early Life on Earth and the Search for Extraterrestrial Biosignatures

    Science.gov (United States)

    Oehler, Dorothy Z.; House, Christopher

    2014-01-01

    In the last 2 years, scientists within the ARES Directorate at JSC have applied the technology of Secondary Ion Mass Spectrometry (SIMS) to individual organic structures preserved in Archean (approximately 3 billion years old) sediments on Earth. These organic structures are among the oldest on Earth that may be microfossils - structurally preserved remnants of ancient microbes. The SIMS work was done to determine the microfossils' stable carbon isotopic composition (delta C-13 values). This is the first time that such ancient, potential microfossils have been successfully analyzed for their individual delta C-13 values. The results support the interpretation that these structures are remnants of early life on Earth and that they may represent planktonic organisms that were widely distributed in the Earth's earliest oceans. This study has been accepted for publication in the journal Geology.

  7. Early differentiation of the Earth and the Moon.

    Science.gov (United States)

    Bourdon, Bernard; Touboul, Mathieu; Caro, Guillaume; Kleine, Thorsten

    2008-11-28

    We examine the implications of new 182W and 142Nd data for Mars and the Moon for the early evolution of the Earth. The similarity of 182W in the terrestrial and lunar mantles and their apparently differing Hf/W ratios indicate that the Moon-forming giant impact most probably took place more than 60Ma after the formation of calcium-aluminium-rich inclusions (4.568Gyr). This is not inconsistent with the apparent U-Pb age of the Earth. The new 142Nd data for Martian meteorites show that Mars probably has a super-chondritic Sm/Nd that could coincide with that of the Earth and the Moon. If this is interpreted by an early mantle differentiation event, this requires a buried enriched reservoir for the three objects. This is highly unlikely. For the Earth, we show, based on new mass-balance calculations for Nd isotopes, that the presence of a hidden reservoir is difficult to reconcile with the combined 142Nd-143Nd systematics of the Earth's mantle. We argue that a likely possibility is that the missing component was lost during or prior to accretion. Furthermore, the 142Nd data for the Moon that were used to argue for the solidification of the magma ocean at ca 200Myr are reinterpreted. Cumulate overturn, magma mixing and melting following lunar magma ocean crystallization at 50-100Myr could have yielded the 200Myr model age.

  8. The rise of oxygen in Earth's early ocean and atmosphere

    Science.gov (United States)

    Lyons, Timothy W.; Reinhard, Christopher T.; Planavsky, Noah J.

    2014-02-01

    The rapid increase of carbon dioxide concentration in Earth's modern atmosphere is a matter of major concern. But for the atmosphere of roughly two-and-half billion years ago, interest centres on a different gas: free oxygen (O2) spawned by early biological production. The initial increase of O2 in the atmosphere, its delayed build-up in the ocean, its increase to near-modern levels in the sea and air two billion years later, and its cause-and-effect relationship with life are among the most compelling stories in Earth's history.

  9. Electrical energy sources for organic synthesis on the early earth

    Science.gov (United States)

    Chyba, Christopher; Sagan, Carl

    1991-01-01

    In 1959, Miller and Urey (Science 130, 245) published their classic compilation of energy sources for indigenous prebiotic organic synthesis on the early Earth. Much contemporary origins of life research continues to employ their original estimates for terrestrial energy dissipation by lightning and coronal discharges, 2 × 1019 J yr-1 and 6 × 1019 J yr-1, respectively. However, more recent work in terrestrial lightning and point discharge research suggests that these values are overestimates by factors of about 20 and 120, respectively. Calculated concentrations of amino acids (or other prebiotic organic products) in the early terrestrial oceans due to electrical discharge sources may therefore have been equally overestimated. A review of efficiencies for those experiments that provide good analogues to naturally-occurring lightning and coronal discharges suggests that lightning energy yields for organic synthesis (nmole J-1) are about one order of magnitude higher than those for coronal discharge. Therefore organic production by lightning may be expected to have dominated that due to coronae on early Earth. Limited data available for production of nitric oxide in clouds suggests that coronal emission within clouds, a source of energy heretofore too uncertain to be included in the total coronal energy inventory, is insufficient to change this conclusion. Our recommended valves for lightning and coronal discharge dissipation rates on the early Earth are, respectively, 1 × 1018 J yr-1 and 5 × 1017 J yr-1.

  10. Mineral remains of early life on Earth? On Mars?

    Science.gov (United States)

    Iberall, Robbins E.; Iberall, A.S.

    1991-01-01

    The oldest sedimentary rocks on Earth, the 3.8-Ga Isua Iron-Formation in southwestern Greenland, are metamorphosed past the point where organic-walled fossils would remain. Acid residues and thin sections of these rocks reveal ferric microstructures that have filamentous, hollow rod, and spherical shapes not characteristic of crystalline minerals. Instead, they resemble ferric-coated remains of bacteria. Because there are no earlier sedimentary rocks to study on Earth, it may be necessary to expand the search elsewhere in the solar system for clues to any biotic precursors or other types of early life. A study of morphologies of iron oxide minerals collected in the southern highlands during a Mars sample return mission may therefore help to fill in important gaps in the history of Earth's earliest biosphere. -from Authors

  11. Hydrogenation of iron in the early stage of Earth's evolution

    Science.gov (United States)

    Iizuka-Oku, Riko; Yagi, Takehiko; Gotou, Hirotada; Okuchi, Takuo; Hattori, Takanori; Sano-Furukawa, Asami

    2017-01-01

    Density of the Earth's core is lower than that of pure iron and the light element(s) in the core is a long-standing problem. Hydrogen is the most abundant element in the solar system and thus one of the important candidates. However, the dissolution process of hydrogen into iron remained unclear. Here we carry out high-pressure and high-temperature in situ neutron diffraction experiments and clarify that when the mixture of iron and hydrous minerals are heated, iron is hydrogenized soon after the hydrous mineral is dehydrated. This implies that early in the Earth's evolution, as the accumulated primordial material became hotter, the dissolution of hydrogen into iron occurred before any other materials melted. This suggests that hydrogen is likely the first light element dissolved into iron during the Earth's evolution and it may affect the behaviour of the other light elements in the later processes.

  12. A Hot Climate on Early Earth: Implications to Biospheric Evolution

    Science.gov (United States)

    Schwartzman, D. W.; Knauth, L. P.

    2009-12-01

    There is now robust evidence for a much warmer climate on the early Earth than now. Both oxygen and silicon isotopes in sedimentary chert and the compelling case for a near constant isotopic oxygen composition of seawater over geologic time support thermophilic surface temperatures until about 1.5-2 billion years ago, aside from a glacial episode in the early Proterozoic. This temperature scenario has important implications to biospheric evolution, including a temperature constraint that held back the emergence of major organismal groups, starting with phototrophs. A geophysiology of biospheric evolution raises the potential of similar coevolutionary relationships of life and its environment on Earth-like planets around Sun-like stars.

  13. Electrical energy sources for organic synthesis on the early earth

    Science.gov (United States)

    Chyba, Christopher; Sagan, Carl

    1991-01-01

    It is pointed out that much of the contemporary origin-of-life research uses the original estimates of Miller and Urey (1959) for terrestrial energy dissipation by lightning and coronal discharges being equal to 2 x 10 to the 19th J/yr and 6 x 10 to the 19th J/yr, respectively. However, data from experiments that provide analogues to naturally-occurring lightning and coronal discharges indicate that lightning energy yields for organic synthesis (nmole/J) are about one order of magnitude higher than the coronal discharge yields. This suggests that, on early earth, organic production by lightning may have dominated that due to coronal emission. New values are recommended for lightning and coronal discharge dissipation rates on the early earth, 1 x 10 to the 18th J/yr and 5 x 10 to the 17th J/yr, respectively.

  14. Hydrogen-nitrogen greenhouse warming in Earth's early atmosphere.

    Science.gov (United States)

    Wordsworth, Robin; Pierrehumbert, Raymond

    2013-01-04

    Understanding how Earth has sustained surface liquid water throughout its history remains a key challenge, given that the Sun's luminosity was much lower in the past. Here we show that with an atmospheric composition consistent with the most recent constraints, the early Earth would have been significantly warmed by H(2)-N(2) collision-induced absorption. With two to three times the present-day atmospheric mass of N(2) and a H(2) mixing ratio of 0.1, H(2)-N(2) warming would be sufficient to raise global mean surface temperatures above 0°C under 75% of present-day solar flux, with CO(2) levels only 2 to 25 times the present-day values. Depending on their time of emergence and diversification, early methanogens may have caused global cooling via the conversion of H(2) and CO(2) to CH(4), with potentially observable consequences in the geological record.

  15. Electrical energy sources for organic synthesis on the early earth

    Science.gov (United States)

    Chyba, Christopher; Sagan, Carl

    1991-01-01

    It is pointed out that much of the contemporary origin-of-life research uses the original estimates of Miller and Urey (1959) for terrestrial energy dissipation by lightning and coronal discharges being equal to 2 x 10 to the 19th J/yr and 6 x 10 to the 19th J/yr, respectively. However, data from experiments that provide analogues to naturally-occurring lightning and coronal discharges indicate that lightning energy yields for organic synthesis (nmole/J) are about one order of magnitude higher than the coronal discharge yields. This suggests that, on early earth, organic production by lightning may have dominated that due to coronal emission. New values are recommended for lightning and coronal discharge dissipation rates on the early earth, 1 x 10 to the 18th J/yr and 5 x 10 to the 17th J/yr, respectively.

  16. Follow the Carbon: Isotopic Labeling Studies of Early Earth Aerosol.

    Science.gov (United States)

    Hicks, Raea K; Day, Douglas A; Jimenez, Jose L; Tolbert, Margaret A

    2016-11-01

    Despite the faint young Sun, early Earth might have been kept warm by an atmosphere containing the greenhouse gases CH4 and CO2 in mixing ratios higher than those found on Earth today. Laboratory and modeling studies suggest that an atmosphere containing these trace gases could lead to the formation of organic aerosol haze due to UV photochemistry. Chemical mechanisms proposed to explain haze formation rely on CH4 as the source of carbon and treat CO2 as a source of oxygen only, but this has not previously been verified experimentally. In the present work, we use isotopically labeled precursor gases and unit-mass resolution (UMR) and high-resolution (HR) aerosol mass spectrometry to examine the sources of carbon and oxygen to photochemical aerosol formed in a CH4/CO2/N2 atmosphere. UMR results suggest that CH4 contributes 70-100% of carbon in the aerosol, while HR results constrain the value from 94% to 100%. We also confirm that CO2 contributes approximately 10% of the total mass to the aerosol as oxygen. These results have implications for the geochemical interpretations of inclusions found in Archean rocks on Earth and for the astrobiological potential of other planetary atmospheres. Key Words: Atmosphere-Early Earth-Planetary atmospheres-Carbon dioxide-Methane. Astrobiology 16, 822-830.

  17. Isotope composition and volume of Earth's early oceans.

    Science.gov (United States)

    Pope, Emily C; Bird, Dennis K; Rosing, Minik T

    2012-03-20

    Oxygen and hydrogen isotope compositions of Earth's seawater are controlled by volatile fluxes among mantle, lithospheric (oceanic and continental crust), and atmospheric reservoirs. Throughout geologic time the oxygen mass budget was likely conserved within these Earth system reservoirs, but hydrogen's was not, as it can escape to space. Isotopic properties of serpentine from the approximately 3.8 Ga Isua Supracrustal Belt in West Greenland are used to characterize hydrogen and oxygen isotope compositions of ancient seawater. Archaean oceans were depleted in deuterium [expressed as δD relative to Vienna standard mean ocean water (VSMOW)] by at most 25 ± 5‰, but oxygen isotope ratios were comparable to modern oceans. Mass balance of the global hydrogen budget constrains the contribution of continental growth and planetary hydrogen loss to the secular evolution of hydrogen isotope ratios in Earth's oceans. Our calculations predict that the oceans of early Earth were up to 26% more voluminous, and atmospheric CH(4) and CO(2) concentrations determined from limits on hydrogen escape to space are consistent with clement conditions on Archaean Earth.

  18. Implications for the Earth of the early dynamical environment

    Science.gov (United States)

    Kaula, W. M.; Cooperman, S. A.

    1985-01-01

    The formation of the Earth, was mainly from sizeable bodies: perhaps moon sized. Models of interaction among small planetesimals which take into account only close encounters all lead to the formation of moon sized objects, thus leading to several 100 in the inner solar system. Longer term interactions, such as secular resonance sweepings, are needed to get these planetesimals together to form the observed terrestrial bodies. After the accumulation of the Earth, during which core formation certainly occurred, further impacts probably influenced the locations of rifting centers in the system of mantle convection and crustal differentiation. They may have affected craton stabilization by promoting lateral heterogeneity, but had little influence on the key problem of early recycling of sial.

  19. Early Life on Earth: the Ancient Fossil Record

    Science.gov (United States)

    Westall, F.

    2004-07-01

    The evidence for early life and its initial evolution on Earth is lin= ked intimately with the geological evolution of the early Earth. The environment of the early Earth would be considered extreme by modern standards: hot (50-80=B0C), volcanically and hydrothermally active, a= noxic, high UV flux, and a high flux of extraterrestrial impacts. Habitats = for life were more limited until continent-building processes resulted in= the formation of stable cratons with wide, shallow, continental platforms= in the Mid-Late Archaean. Unfortunately there are no records of the first appearance of life and the earliest isotopic indications of the exist= ence of organisms fractionating carbon in ~3.8 Ga rocks from the Isua greenst= one belt in Greenland are tenuous. Well-preserved microfossils and micro= bial mats (in the form of tabular and domical stromatolites) occur in 3.5-= 3.3 Ga, Early Archaean, sedimentary formations from the Barberton (South Afri= ca) and Pilbara (Australia) greenstone belts. They document life forms that = show a relatively advanced level of evolution. Microfossil morphology inclu= des filamentous, coccoid, rod and vibroid shapes. Colonial microorganism= s formed biofilms and microbial mats at the surfaces of volcaniclastic = and chemical sediments, some of which created (small) macroscopic microbi= alites such as stromatolites. Anoxygenic photosynthesis may already have developed. Carbon, nitrogen and sulphur isotopes ratios are in the r= ange of those for organisms with anaerobic metabolisms, such as methanogenesi= s, sulphate reduction and photosynthesis. Life was apparently distribute= d widely in shallow-water to littoral environments, including exposed, evaporitic basins and regions of hydrothermal activity. Biomass in t= he early Archaean was restricted owing to the limited amount of energy t= hat could be produced by anaerobic metabolisms. Microfossils resembling o= xygenic photosynthesisers, such as cyanobacteria, probably first occurred in

  20. Prebiotic materials from on and off the early Earth.

    Science.gov (United States)

    Bernstein, Max

    2006-10-29

    One of the greatest puzzles of all time is how did life arise? It has been universally presumed that life arose in a soup rich in carbon compounds, but from where did these organic molecules come? In this article, I will review proposed terrestrial sources of prebiotic organic molecules, such as Miller-Urey synthesis (including how they would depend on the oxidation state of the atmosphere) and hydrothermal vents and also input from space. While the former is perhaps better known and more commonly taught in school, we now know that comet and asteroid dust deliver tons of organics to the Earth every day, therefore this flux of reduced carbon from space probably also played a role in making the Earth habitable. We will compare and contrast the types and abundances of organics from on and off the Earth given standard assumptions. Perhaps each process provided specific compounds (amino acids, sugars, amphiphiles) that were directly related to the origin or early evolution of life. In any case, whether planetary, nebular or interstellar, we will consider how one might attempt to distinguish between abiotic organic molecules from actual signs of life as part of a robotic search for life in the Solar System.

  1. Summary

    Science.gov (United States)

    Habing, H.

    2004-07-01

    Summaries of conferences consist of subjective views of the reviewer, on what he remarked, of what he thought was important. And yet some of these remarks may be of interest to all participants. The event called "inspiration" may happen when scientist A gets an idea because of a brilliant or of stupid remark she heard when scientist B gave a summary. So, what is a good review? A review that broadens the perspective of at least some people in the audience. I hope that my attempt works. Let's see.

  2. Hydrogen consumption by methanogens on the early Earth

    Science.gov (United States)

    Kral, T. A.; Brink, K. M.; Miller, S. L.; McKay, C. P.; Bada, J. L. (Principal Investigator)

    1998-01-01

    It is possible that the first autotroph used chemical energy rather than light. This could have been the main source of primary production after the initial inventory of abiotic organic material had been depleted. The electron acceptor most readily available for use by this first chemoautotroph would have been CO2. The most abundant electron donor may have been H2 that would have been outgassing from volcanoes at a rate estimated to be as large as 10(12) moles yr-1, as well as from photo-oxidation of Fe+2. We report here that certain methanogens will consume H2 down to partial pressures as low as 4 Pa (4 x 10(-5) atm) with CO2 as the sole carbon source at a rate of 0.7 ng H2 min-1 microgram-1 cell protein. The lower limit of pH2 for growth of methanogens can be understood on the basis that the pH2 needs to be high enough for one ATP to be synthesized per CO2 reduced. The pH2 values needed for growth measured here are consistent with those measured by Stevens and McKinley for growth of methanogens in deep basalt aquifers. H2-consuming autotrophs are likely to have had a profound effect on the chemistry of the early atmosphere and to have been a dominant sink for H2 on the early Earth after life began rather than escape from the Earth's atmosphere to space.

  3. Continental crust formation on early Earth controlled by intrusive magmatism

    Science.gov (United States)

    Rozel, A. B.; Golabek, G. J.; Jain, C.; Tackley, P. J.; Gerya, T.

    2017-05-01

    The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism and the “Plutonic squishy lid” tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.

  4. Continental crust formation on early Earth controlled by intrusive magmatism.

    Science.gov (United States)

    Rozel, A B; Golabek, G J; Jain, C; Tackley, P J; Gerya, T

    2017-05-18

    The global geodynamic regime of early Earth, which operated before the onset of plate tectonics, remains contentious. As geological and geochemical data suggest hotter Archean mantle temperature and more intense juvenile magmatism than in the present-day Earth, two crust-mantle interaction modes differing in melt eruption efficiency have been proposed: the Io-like heat-pipe tectonics regime dominated by volcanism and the "Plutonic squishy lid" tectonics regime governed by intrusive magmatism, which is thought to apply to the dynamics of Venus. Both tectonics regimes are capable of producing primordial tonalite-trondhjemite-granodiorite (TTG) continental crust but lithospheric geotherms and crust production rates as well as proportions of various TTG compositions differ greatly, which implies that the heat-pipe and Plutonic squishy lid hypotheses can be tested using natural data. Here we investigate the creation of primordial TTG-like continental crust using self-consistent numerical models of global thermochemical convection associated with magmatic processes. We show that the volcanism-dominated heat-pipe tectonics model results in cold crustal geotherms and is not able to produce Earth-like primordial continental crust. In contrast, the Plutonic squishy lid tectonics regime dominated by intrusive magmatism results in hotter crustal geotherms and is capable of reproducing the observed proportions of various TTG rocks. Using a systematic parameter study, we show that the typical modern eruption efficiency of less than 40 per cent leads to the production of the expected amounts of the three main primordial crustal compositions previously reported from field data (low-, medium- and high-pressure TTG). Our study thus suggests that the pre-plate-tectonics Archean Earth operated globally in the Plutonic squishy lid regime rather than in an Io-like heat-pipe regime.

  5. Biomarkers as tracers for life on early earth and Mars

    Science.gov (United States)

    Simoneit, B. R.; Summons, R. E.; Jahnke, L. L.

    1998-01-01

    Biomarkers in geological samples are products derived from biochemical (natural product) precursors by reductive and oxidative processes (e.g., cholestanes from cholesterol). Generally, lipids, pigments and biomembranes are preserved best over longer geological times and labile compounds such as amino acids, sugars, etc. are useful biomarkers for recent times. Thus, the detailed characterization of biomarker compositions permits the assessment of the major contributing species of extinct and/or extant life. In the case of the early Earth, work has progressed to elucidate molecular structure and carbon isotropic signals preserved in ancient sedimentary rocks. In addition, the combination of bacterial biochemistry with the organic geochemistry of contemporary and ancient hydrothermal ecosystems permits the modeling of the nature, behavior and preservation potential of primitive microbial communities. This approach uses combined molecular and isotopic analyses to characterize lipids produced by cultured bacteria (representative of ancient strains) and to test a variety of culture conditions which affect their biosynthesis. On considering Mars, the biomarkers from lipids and biopolymers would be expected to be preserved best if life flourished there during its early history (3.5-4 x 10(9) yr ago). Both oxidized and reduced products would be expected. This is based on the inferred occurrence of hydrothermal activity during that time with the concomitant preservation of biochemically-derived organic matter. Both known biomarkers (i.e., as elucidated for early terrestrial samples and for primitive terrestrial microbiota) and novel, potentially unknown compounds should be characterized.

  6. Writing on the earth: Early European travellers to South Africa

    Directory of Open Access Journals (Sweden)

    M. Sienaert

    1996-05-01

    Full Text Available The issue of land in South Africa has always been problematic. This is to be expected in a country whose history has been one of colonisation, contested borders and, in the more recent apartheid past, of legalised removals of people from the land. In recent post-colonial theory too, the notion of spatiality has proved to be significant: to write a history of a country and its people is to write a spatial history through the processes of naming, mapping, classifying and painting. Our project in this article is to explore some of the ways in which early European travellers to South Africa traced their presence in this country, and in so doing began a chapter of “writing on the earth", the ideological marks of which linger on into this century.

  7. Cometary delivery of organic molecules to the early Earth.

    Science.gov (United States)

    Chyba, C F; Thomas, P J; Brookshaw, L; Sagan, C

    1990-07-27

    It has long been speculated that Earth accreted prebiotic organic molecules important for the origins of life from impacts of carbonaceous asteroids and comets during the period of heavy bombardment 4.5 x 10(9) to 3.8 x 10(9) years ago. A comprehensive treatment of comet-asteroid interaction with the atmosphere, surface impact, and resulting organic pyrolysis demonstrates that organics will not survive impacts at velocities greater than about 10 kilometers per second and that even comets and asteroids as small as 100 meters in radius cannot be aerobraked to below this velocity in 1-bar atmospheres. However, for plausible dense (10-bar carbon dioxide) early atmospheres, we find that 4.5 x 10(9) years ago Earth was accreting intact cometary organics at a rate of at least approximately 10(6) to 10(7) kilograms per year, a flux that thereafter declined with a half-life of approximately 10(8) years. These results may be put in context by comparison with terrestrial oceanic and total biomasses, approximately 3 x 10(12) kilograms and approximately 6 x 10(14) kilograms, respectively.

  8. Photochemistry of methane in the earth's early atmosphere

    Science.gov (United States)

    Kasting, J. F.; Zahnle, K J.; Walker, J. C. G.

    1983-01-01

    The photochemical behavior of methane in the early terrestrial atmosphere is investigated with a detailed model in order to determine how much CH4 might have been present and what types of higher hydroocarbons could have been formed. It is found that any primordial methane accumulated during the course of earth accretion would have been dissipated by photochemical reactions in the atmosphere in a geologically short period of time after the segregation of the core. Abiotic sources of methane are not likely to have been large enough to sustain CH4 mixing ratios as high as 10 to the -6th, the threshold for a possible methane greenhouse, with a CO-rich atmosphere being a possible exception. After the origin of life an increasing biogenic source of methane may have driven CH4 mixing ratios well above 10 to the 6th. The rise of atmospheric oxygen in the early Proterozoic may have led to a more rapid photochemical destruction of methane, lowering the mixing ratio to its present value.

  9. Summary

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Social History of Science The concept of "Social History of Science" was perhaps initiated by the Chinese, for as far as We know, most related studies abroad with this concept as the title of their books appeared in the 21st century, such as the book by a Japanese A Social History of Science and Technology in Contemporary Japan: The Occupation Period, 1945-1952 (Trans Pacific Pr., 2001), and the book by an Indian Social History of Science in Colonial India (Oxford University Pr., 2007), etc. Earlier indeed in Steven Shapin's book A Social History of Truth: Civility and Science in Seventeenth-Century England (University of Chicago Pr., 1994), a similar concept had appeared. As early as in November, 1984, in China, however, the concept of "Social History of Science" was used at the "Colloquium for Social History of Science" held in Xiamen, Fujian.

  10. Global-scale water circulation in the Earth's mantle: Implications for the mantle water budget in the early Earth

    Science.gov (United States)

    Nakagawa, Takashi; Spiegelman, Marc W.

    2017-04-01

    We investigate the influence of the mantle water content in the early Earth on that in the present mantle using numerical convection simulations that include three processes for redistribution of water: dehydration, partitioning of water into partially molten mantle, and regassing assuming an infinite water reservoir at the surface. These models suggest that the water content of the present mantle is insensitive to that of the early Earth. The initial water stored during planetary formation is regulated up to 1.2 OMs (OM = Ocean Mass; 1.4 ×1021 kg), which is reasonable for early Earth. However, the mantle water content is sensitive to the rheological dependence on the water content and can range from 1.2 to 3 OMs at the present day. To explain the evolution of mantle water content, we computed water fluxes due to subducting plates (regassing), degassing and dehydration. For weakly water dependent viscosity, the net water flux is almost balanced with those three fluxes but, for strongly water dependent viscosity, the regassing dominates the water cycle system because the surface plate activity is more vigorous. The increased convection is due to enhanced lubrication of the plates caused by a weak hydrous crust for strongly water dependent viscosity. The degassing history is insensitive to the initial water content of the early Earth as well as rheological strength. The degassing flux from Earth's surface is calculated to be approximately O (1013) kg /yr, consistent with a coupled model of climate evolution and mantle thermal evolution.

  11. Effects of differentiation on the geodynamics of the early Earth

    Science.gov (United States)

    Piccolo, Andrea; Kaus, Boris; White, Richard; Johnson, Tim

    2016-04-01

    Archean geodynamic processes are not well understood, but there is general agreement that the mantle potential temperature was higher than present, and that as a consequence significant amounts of melt were produced both in the mantle and any overlying crust. This has likely resulted in crustal differentiation. An early attempt to model the geodynamic effects of differentiation was made by Johnson et al. (2014), who used numerical modeling to investigate the crust production and recycling in conjunction with representative phase diagrams (based on the inferred chemical composition of the primary melt in accordance with the Archean temperature field). The results of the simulations show that the base of the over-thickened primary basaltic crust becomes gravitational unstable due to the mineral assemblage changes. This instability leads to the dripping of dense material into the mantle, which causes an asthenospheric return flow, local partial melting and new primary crust generation that is rapidly recycled in to mantle. Whereas they gave important insights, the previous simulations were simplified in a number of aspects: 1) the rheology employed was viscous, and both elasticity and pressure-dependent plasticity were not considered; 2) extracted mantle melts were 100% transformed into volcanic rocks, whereas on the present day Earth only about 20-30% are volcanic and the remainder is plutonic; 3) the effect of a free surface was not studied in a systematic manner. In order to better understand how these simplifications affect the geodynamic models, we here present additional simulations to study the effects of each of these parameters. Johnson, T.E., Brown, M., Kaus, B., and VanTongeren, J.A., 2014, Delamination and recycling of Archaean crust caused by gravitational instabilities: Nature Geoscience, v. 7, no. 1, p. 47-52, doi: 10.1038/NGEO2019.

  12. PROJECT W-551 SUMMARY INFORMATION FOR EARLY LAW INTERIM PRETREATMENT SYSTEM SELECTION

    Energy Technology Data Exchange (ETDEWEB)

    AR, TEDESCHI

    2008-08-11

    This report provides summary data for use by the decision board to assess and select the final technology for project W-551, Interim Pretreatment System. This project will provide early pretreated low activity waste feed to the Waste Treatment Plant to allow Waste Treatment Plan Low Activity Waste facility operation prior to construction completion of the Pretreatment and High Level Waste facilities. The candidate solids separations technologies are rotary microfiltration and crossflow filtration, and the candidate cesium separation technologies are fractional crystallization, caustic-side solvent extraction, and ion-exchange using spherical resorcinol-fonnaldebyde resin. This document provides a summary of comparative data against prior weighted criteria to support technology selection. Supporting details and background for this summary are documented in the separate report, RPP-RPT-37741.

  13. The Early Years: The Earth-Sun System

    Science.gov (United States)

    Ashbrook, Peggy

    2015-01-01

    We all experience firsthand many of the phenomena caused by Earth's Place in the Universe (Next Generation Science Standard 5-ESS1; NGSS Lead States 2013) and the relative motion of the Earth, Sun, and Moon. Young children can investigate phenomena such as changes in times of sunrise and sunset (number of daylight hours), Moon phases, seasonal…

  14. Ocean Fertilization from Giant Icebergs on Earth and Early Mars

    Science.gov (United States)

    Uceda, E. R.; Fairen, A. G.; Rodriguez, J. A. P.; Woodworth-Lynas, C.

    2016-05-01

    Assuming that life existed on Mars coeval to glacial activity, enhanced concentrations of organic carbon could be anticipated near iceberg trails, analogous to what is observed in polar oceans on Earth.

  15. A model for core formation in the early Earth

    Science.gov (United States)

    Jones, J. H.; Drake, M. J.

    1985-01-01

    Two basic types exogenous models were proposed to account for siderophile and chalcophile element abundances in the Earth's upper mantle. The first model requires that the Earth be depleted in volatiles and that, after a core formation event which extracted the most siderophile elements into the core, additional noble siderophile elements (Pt, Ir, Au) were added as a late veneer and mixed into the mantle. The second model postulates a reduced Earth with approximately CI elemental abundances in which a primary core forming event depleted all siderophile elements in the mantle. The plausibility of models which require fine scale mixing of chondritic material into the upper mantle is analyzed. Mixing in liquids is more efficient, but large degrees of silicate partial melting will facilitate the separation of magma from residual solids. Any external events affecting the upper mantle of the Earth should also be evident in the Moon; but siderophile and chalcophile element abundance patterns inferred for the mantles of the Earth and Moon differ. There appear to be significant physical difficulties associated with chondritic veneer models.

  16. Massive impact-induced release of carbon and sulfur gases in the early Earth's atmosphere

    Science.gov (United States)

    Marchi, S.; Black, B. A.; Elkins-Tanton, L. T.; Bottke, W. F.

    2016-09-01

    Recent revisions to our understanding of the collisional history of the Hadean and early-Archean Earth indicate that large collisions may have been an important geophysical process. In this work we show that the early bombardment flux of large impactors (>100 km) facilitated the atmospheric release of greenhouse gases (particularly CO2) from Earth's mantle. Depending on the timescale for the drawdown of atmospheric CO2, the Earth's surface could have been subject to prolonged clement surface conditions or multiple freeze-thaw cycles. The bombardment also delivered and redistributed to the surface large quantities of sulfur, one of the most important elements for life. The stochastic occurrence of large collisions could provide insights on why the Earth and Venus, considered Earth's twin planet, exhibit radically different atmospheres.

  17. Prebiotic materials from on and off the early Earth

    Science.gov (United States)

    Bernstein, Max

    2006-01-01

    One of the great puzzles of all time is how did life arise? It has been universally presumed that life arose in a soup rich in compounds made mostly of carbon, the kind of which we are currently composed. Where did these organic molecules come from? In this talk I will review proposed contributions to pre-biotic organic chemistry from both terrestrial processes (i.e., hydrothermal vents, Miller-Urey syntheses) and also from space. While the former is perhaps better known and more commonly taught in school, we now know that comet and asteroid dust deliver tons of organics to the Earth every day, and there is a growing consensus among scientists that molecules from space played an important role in making the Earth habitable, and perhaps even provided specific compounds that were directly related to the origin of life.

  18. Evolution of the Early Earth and Its Biosphere

    Science.gov (United States)

    DesMarais, David J.

    1996-01-01

    The history of life on Earth is a rich tapestry of adaptation and innovation which was shaped, at least in part, by the changing surface environment of our planet. To the extent that all rocky planets have followed similar evolutionary paths, studies of our own biosphere can guide us in our search for extraterrestrial life. Understanding the nature, timing, and causes of long-term changes in the global environment is a key objective.

  19. Phenomenology of the earth's bow shock system - A summary description of experimental results

    Science.gov (United States)

    Greenstadt, E. W.

    1976-01-01

    Observational data on the earth's bow shock system are classified and characterized. Foreshock components, midshock components, and aftershock components are discussed separately. Schematic representations of the field and plasma particle parameters are elaborated, with attention given to quasi-perpendicular geometry and quasi-parallel geometry. Magnetic pulsation structure is delineated. Schematic profiles of field, particle, and wave behavior through a representative quasi-perpendicular shock crossing are displayed.

  20. Environmental Consequences of Big Nasty Impacts on the Early Earth

    Science.gov (United States)

    Zahnle, K. J.

    2015-12-01

    The geological record of the Archean Earth is spattered with impact spherules from a dozen or so major cosmic collisions involving Earth and asteroids or comets (Lowe, Byerly 1986, 2015). Extrapolation of the documented deposits suggests that most of these impacts were as big or bigger than the Chicxulub event that famously ended the reign of the thunder lizards. As the Archean impacts were greater, the environmental effects were also greater. The number and magnitude of the impacts is bounded by the lunar record. There are no lunar craters bigger than Chicxulub that date to Earth's mid-to-late Archean. Chance dictates that Earth experienced ~10 impacts bigger than Chicxulub between 2.5 Ga and 3.5 Ga, the biggest of which were ~30-100X more energetic than Chicxulub. To quantify the thermal consequences of big impacts on old Earth, we model the global flow of energy from the impact into the environment. The model presumes that a significant fraction of the impact energy goes into ejecta that interact with the atmosphere. Much of this energy is initially in rock vapor, melt, and high speed particles. (i) The upper atmosphere is heated by ejecta as they reenter the atmosphere. The mix of hot air, rock vapor, and hot silicates cools by thermal radiation. Rock raindrops fall out as the upper atmosphere cools. (ii) The energy balance of the lower atmosphere is set by radiative exchange with the upper atmosphere and with the surface, and by evaporation of seawater. Susequent cooling is governed by condensation of water vapor. (iii) The oceans are heated by thermal radiation and rock rain and cooled by evaporation. Surface waters become hot and salty; if a deep ocean remains it is relatively cool. Subsequently water vapor condenses to replenish the oceans with hot fresh water (how fresh depending on continental weathering, which might be rather rapid under the circumstances). (iv) The surface temperature of dry land is presumed to be the same as the lower atmosphere. A

  1. Environmental Consequences of Big Nasty Impacts on the Early Earth

    Science.gov (United States)

    Zahnle, Kevin

    2015-01-01

    The geological record of the Archean Earth is spattered with impact spherules from a dozen or so major cosmic collisions involving Earth and asteroids or comets (Lowe, Byerly 1986, 2015). Extrapolation of the documented deposits suggests that most of these impacts were as big or bigger than the Chicxulub event that famously ended the reign of the thunder lizards. As the Archean impacts were greater, the environmental effects were also greater. The number and magnitude of the impacts is bounded by the lunar record. There are no lunar craters bigger than Chicxulub that date to Earth's mid-to-late Archean. Chance dictates that Earth experienced no more than approximately 10 impacts bigger than Chicxulub between 2.5 billion years and 3.5 2.5 billion years, the biggest of which were approximately30-100 times more energetic, comparable to the Orientale impact on the Moon (1x10 (sup 26) joules). To quantify the thermal consequences of big impacts on old Earth, we model the global flow of energy from the impact into the environment. The model presumes that a significant fraction of the impact energy goes into ejecta that interact with the atmosphere. Much of this energy is initially in rock vapor, melt, and high speed particles. (i) The upper atmosphere is heated by ejecta as they reenter the atmosphere. The mix of hot air, rock vapor, and hot silicates cools by thermal radiation. Rock raindrops fall out as the upper atmosphere cools. (ii) The energy balance of the lower atmosphere is set by radiative exchange with the upper atmosphere and with the surface, and by evaporation of seawater. Susequent cooling is governed by condensation of water vapor. (iii) The oceans are heated by thermal radiation and rock rain and cooled by evaporation. Surface waters become hot and salty; if a deep ocean remains it is relatively cool. Subsequently water vapor condenses to replenish the oceans with hot fresh water (how fresh depending on continental weathering, which might be rather rapid

  2. Photosynthetic microbial mats today, on early Earth, (and on early Mars?)

    Science.gov (United States)

    Des Marais, D. J.

    2008-05-01

    extensive, highly productive biosphere? Perhaps the substantial decline in geothermal activity during the Archean created a driver for the development of oxygenic photosynthesis. Can we further document the Archean biosphere? The pre-3.5 Ga crust of Mars records evidence of surface water and is far better preserved than the early crust of Earth. Perhaps Mars exploration will extend our understanding of emerging biospheres to even earlier periods.

  3. Schreibersite on the early Earth: Scenarios for prebiotic phosphorylation

    Directory of Open Access Journals (Sweden)

    Matthew A. Pasek

    2017-03-01

    Full Text Available The mineral schreibersite, (Fe,Ni3P, provides a reactive source of phosphorus capable of forming phosphorylated molecules. These molecules may have been an important component of prebiotic chemistry, allowing their build-up and eventual commencement of autopoiesis. Discussed here are potential geochemical routes to providing schreibersite, as a potentially important prebiotic mineral, to the Hadean Earth. Two routes are identified: delivery of phosphides by meteoritic material and the reduction of phosphates to phosphides by high-temperature, low-redox conditions. About 1–10% of all crustal phosphorus is estimated to have been in schreibersite during the Hadean, making the long-term reaction of this mineral with organic-laden water plausible for many years. Ultimately, such conditions would have been conducive to the formation of life as we know it today.

  4. The earth radiation budget experiment: Early validation results

    Science.gov (United States)

    Smith, G. Louis; Barkstrom, Bruce R.; Harrison, Edwin F.

    The Earth Radiation Budget Experiment (ERBE) consists of radiometers on a dedicated spacecraft in a 57° inclination orbit, which has a precessional period of 2 months, and on two NOAA operational meteorological spacecraft in near polar orbits. The radiometers include scanning narrow field-of-view (FOV) and nadir-looking wide and medium FOV radiometers covering the ranges 0.2 to 5 μm and 5 to 50 μm and a solar monitoring channel. This paper describes the validation procedures and preliminary results. Each of the radiometer channels underwent extensive ground calibration, and the instrument packages include in-flight calibration facilities which, to date, show negligible changes of the instruments in orbit, except for gradual degradation of the suprasil dome of the shortwave wide FOV (about 4% per year). Measurements of the solar constant by the solar monitors, wide FOV, and medium FOV radiometers of two spacecraft agree to a fraction of a percent. Intercomparisons of the wide and medium FOV radiometers with the scanning radiometers show agreement of 1 to 4%. The multiple ERBE satellites are acquiring the first global measurements of regional scale diurnal variations in the Earth's radiation budget. These diurnal variations are verified by comparison with high temporal resolution geostationary satellite data. Other principal investigators of the ERBE Science Team are: R. Cess, SUNY, Stoneybrook; J. Coakley, NCAR; C. Duncan, M. King and A Mecherikunnel, Goddard Space Flight Center, NASA; A. Gruber and A.J. Miller, NOAA; D. Hartmann, U. Washington; F.B. House, Drexel U.; F.O. Huck, Langley Research Center, NASA; G. Hunt, Imperial College, London U.; R. Kandel and A. Berroir, Laboratory of Dynamic Meteorology, Ecole Polytechique; V. Ramanathan, U. Chicago; E. Raschke, U. of Cologne; W.L. Smith, U. of Wisconsin and T.H. Vonder Haar, Colorado State U.

  5. Isotope composition and volume of Earth´s early oceans

    DEFF Research Database (Denmark)

    Pope, Emily Catherine; Bird, Dennis K.; Rosing, Minik Thorleif

    2012-01-01

    Oxygen and hydrogen isotope compositions of Earth´s seawater are controlled by volatile fluxes among mantle, lithospheric (oceanic and continental crust), and atmospheric reservoirs. Throughout geologic time the oxygen mass budget was likely conserved within these Earth system reservoirs......, but hydrogen´s was not, as it can escape to space. Isotopic properties of serpentine from the approximately 3.8 Ga Isua Supracrustal Belt in West Greenland are used to characterize hydrogen and oxygen isotope compositions of ancient seawater. Archaean oceans were depleted in deuterium [expressed as Î...... in Earth´s oceans. Our calculations predict that the oceans of early Earth were up to 26% more voluminous, and atmospheric CH4 and CO2 concentrations determined from limits on hydrogen escape to space are consistent with clement conditions on Archaean Earth....

  6. Excess hafnium-176 in meteorites and the early Earth zircon record

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Connelly, J.N.; Thrane, K.

    2012-01-01

    suggesting early extraction of a continental crust (>4.5 Gyr) but fail to identify a prevalent complementary depleted mantle reservoir, suggesting that crust formation processes in the early Earth were fundamentally distinct from today. However, this conclusion assumes that the Hf-isotope composition of bulk...... chondrite meteorites can be used to estimate the composition of Earth prior to its differentiation into major silicate reservoirs, namely the bulk silicate Earth (BSE). We report a Lu- Hf internal mineral isochron age of 4869 34 Myr for the pristine SAH99555 angrite meteorite. This age is ~300 Myr older...... than the age of the Solar System, confirming the existence of an energetic process yielding excess Hf in affected early formed Solar System objects through the production of the Lu isomer (t ~3.9 hours). Thus, chondrite meteorites contain excess Hf and their present-day composition cannot be used...

  7. Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere

    Science.gov (United States)

    Kasting, James F.; Ackerman, Thomas P.

    1986-01-01

    The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 to 110 C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.

  8. Climatic consequences of very high carbon dioxide levels in the earth's early atmosphere

    Science.gov (United States)

    Kasting, James F.; Ackerman, Thomas P.

    1986-01-01

    The possible consequences of very high carbon dioxide concentrations in the earth's early atmosphere have been investigated with a radiative-convective climate model. The early atmosphere would apparently have been stable against the onset of a runaway greenhouse (that is, the complete evaporation of the oceans) for carbon dioxide pressures up to at least 100 bars. A 10- to 20-bar carbon dioxide atmosphere, such as may have existed during the first several hundred million years of the earth's history, would have had a surface temperature of approximately 85 to 110 C. The early stratosphere should have been dry, thereby precluding the possibility of an oxygenic prebiotic atmosphere caused by photodissociation of water vapor followed by escape of hydrogen to space. Earth's present atmosphere also appears to be stable against a carbon dioxide-induced runaway greenhouse.

  9. Using Lunar Impact Glasses to Inform the Amount of Organic Material Delivered to the Early Earth

    Science.gov (United States)

    Nguyen, Pham; Zellner, Nicolle

    2017-01-01

    The delivery of organic material via comets and asteroids during the early history of Earth plays an important role in some theories about the origin of life on Earth. Given the close proximity of the Moon to the Earth, the Moon’s impact history can be used to estimate the amount of organic material delivered to the early Earth. Analysis of lunar impact glasses, derived from energetic impacts on the Moon, provide valuable data that can be used to interpret the Moon’s impact flux. Here we present the results of a study of the non-volatile lithophile element compositions of over 500 impact glass samples from the Apollo 14, 16, and 17 landing sites, along with associated ages of a subset of them. Our analyses show that many of the impact glasses possess compositions exotic to the local regolith in which they were found. Coupled with their ages, these glasses suggest material transport from distant regions of the Moon and may allow an estimate of the number of lunar (and terrestrial) impactors in a given time period. These results have important implications for constraining the Moon’s impact flux and also the amount of organic material delivered to the early Earth. Results of our preliminary study, which investigates the amounts of organic material delivered by comets and asteroids to the Moon (and Earth), will be presented.

  10. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  11. Earth's Early Biosphere and the Biogeochemical Carbon Cycle

    Science.gov (United States)

    DesMarais, David

    2004-01-01

    Our biosphere has altered the global environment principally by influencing the chemistry of those elements most important for life, e g., C, N, S, O, P and transition metals (e.g., Fe and Mn). The coupling of oxygenic photosynthesis with the burial in sediments of photosynthetic organic matter, and with the escape of H2 to space, has increased the state of oxidation of the Oceans and atmosphere. It has also created highly reduced conditions within sedimentary rocks that have also extensively affected the geochemistry of several elements. The decline of volcanism during Earth's history reduced the flow of reduced chemical species that reacted with photosynthetically produced O2. The long-term net accumulation of photosynthetic O2 via biogeochemical processes has profoundly influenced our atmosphere and biosphere, as evidenced by the O2 levels required for algae, multicellular life and certain modem aerobic bacteria to exist. When our biosphere developed photosynthesis, it tapped into an energy resource that was much larger than the energy available from oxidation-reduction reactions associated with weathering and hydrothermal activity. Today, hydrothermal sources deliver globally (0.13-1.1)x10(exp l2) mol yr(sup -1) of reduced S, Fe(2+), Mn(2+), H2 and CH4; this is estimated to sustain at most about (0.2-2)xl0(exp 12)mol C yr(sup -1) of organic carbon production by chemautotrophic microorganisms. In contrast, global photosynthetic productivity is estimated to be 9000x10(exp 12) mol C yr(sup -1). Thus, even though global thermal fluxes were greater in the distant geologic past than today, the onset of oxygenic photosynthesis probably increased global organic productivity by some two or more orders of magnitude. This enormous productivity materialized principally because oxygenic photosynthesizers unleashed a virtually unlimited supply of reduced H that forever freed life from its sole dependence upon abiotic sources of reducing power such as hydrothermal emanations

  12. Plume tectonics and cratons formation in the early Earth

    Science.gov (United States)

    Gerya, T.; Stern, R. J.; Baes, M.; Fischer, R.; Sizova, E.; Sobolev, S. V.; Whattam, S. A.

    2015-12-01

    Modern geodynamics and continental growth are critically driven by subduction and plate tectonics, however how this tectonic regime started and what geodynamic regime was before remains controversial. Most present-day subduction initiation mechanisms require acting plate forces and/or pre-existing zones of lithospheric weakness, which are themselves the consequence of plate tectonics. Here, we focus on plume-lithosphere interactions and spontaneous plume-induced subduction initiation, which does not require pre-existing lithospheric fabric and is viable for both stagnant lid and mobile/deformable lid conditions. We present results of 2D and 3D numerical modeling of plume-induced deformation and associated crustal growth resulting from tectono-magmatic interaction of ascending mantle plumes with oceanic-type lithosphere. We demonstrate that weakening of the lithosphere by plume-induced magmatism is the key factor allowing for its internal deformation and differentiation resulting in continental crust growth. We also show that plume-lithosphere interaction can enable subduction and rudimentary plate tectonics initiation at the margins of a crustal plateau growing above the plume head. We argue that frequent plume-arc interactions recorded in Archean crust could reflect either short-term plume-induced subduction or plume-induced episodic lithospheric drips. We furthermore suggest a distinct plume-tectonics regime operated on Earth before plate tectonics, which was associated with widespread tectono-magmatic heat and mass exchange between the crust and the mantle. This regime was characterized by weak deformable plates with low topography, massive juvenile crust production from mantle derived melts, mantle-flows-driven crustal deformation, magma-assisted crustal convection and widespread development of lithospheric delamination and crustal drips. Plume tectonics also resulted in growth of hot depleted chemically buoyant subcrustal proto-cratonic mantle layer. Later

  13. What Do We Really Know About the Earth's Early Atmosphere?

    Science.gov (United States)

    Catling, D. C.; Krissansen-Totton, J.; Zahnle, K. J.

    2016-12-01

    ., Murakami T. (2015) Geochim. Cosmochim. Acta 159, 190. [5] Som S. M. et al. (2016) Nature Geosc. 9, 448. [6] Zahnle K. et al. (2006) Geobiology 4, 271. [7] Pope E. C. et al. (2012) P. Natl. Acad. Sci. USA 109, 4371. [8] Pujol M. et al. (2011) Earth Planet Sc Lett 308, 298. [9] Catling D. C. et al. (2001) Science 293, 839.

  14. The early Earth under a superflare and super-CME attack: prospects for life

    Science.gov (United States)

    Airapetian, Vladimir; Glocer, Alex; Gronoff, Guillaume

    Kepler observations suggest that G-type stars produce powerful flares suggesting that the early Earth may also have been exposed to frequent and energetic solar explosive events generated by the young Sun. We show that powerful coronal mass ejection (CME) events associated with superflares impacting the Earth magnetosphere with a frequency of 1 event/day. What was the impact of superflares, CMEs and associated solar energetic particle (SEPs) events on the atmospheric erosion of the young Earth and habitability? In this paper we discuss our three-dimensional (3D) magnetohydrodynamic (MHD) simulations that show that frequent and energetic CMEs from the early Sun continuously destroyed the sub-solar parts of Earth's magnetosphere at heights Photo-collisional dissociation of molecular nitrogen and carbon dioxide creates reactive chemistry that efficiently produces nitrous oxide and hydrogen cyanide, the essential molecule in prebiotic life chemistry. This raises an possibility that frequent super-CMEs could serve as a potential catalyst for the origin of life on early Earth.

  15. Analyzing early exo-Earths with a coupled atmosphere biogeochemical model

    Science.gov (United States)

    Gebauer, Stefanie; Grenfell, John Lee; Stock, Joachim; Lehmann, Ralph; Godolt, Mareike; von Paris, Philip; Rauer, Heike

    2017-04-01

    Investigating Earth-like extrasolar planets with atmospheric models is a central focus in planetary science. Taking the development of Earth as a reference for Earth-like planets we investigate interactions between the atmosphere, planetary surface and organisms. The Great Oxidation Event (GOE) is related to feedbacks between these three. Its origin and controlling mechanisms are not well defined - requiring interdisciplinary, coupled models. We present results from our newly-developed Coupled Atmosphere Biogeochemistry (CAB) model which is unique in the literature. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles governing O2 in early Earth's atmosphere near the GOE. Complicated oxidation pathways play a key role in destroying O2 whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis.

  16. LSU scientists discover evidence of large meteorite impacts on the early earth

    Science.gov (United States)

    Lowe, Donald R.; Byerly, Gary R.

    1988-01-01

    Recent discoveries by scientists at Lousiana State University are examined which may provide a window through which early planetary accretion is viewed and studied and the role of large meteorite impacts on the evolution of life and the earth's surface evaluated.

  17. Alternative Earths: The Diverse Chapters of Sustained Habitability on a Dynamic Early Earth and Their Astrobiological Significance

    Science.gov (United States)

    Lyons, T. W.

    2015-12-01

    The oldest signs of animal life appear in the geologic record 600 to 700 million years ago. For the four billion years prior, our planet experienced dramatic changes that paved the way for this milestone. Beyond the establishment of Earth's earliest oceans 4.3 billion years ago (Ga), the single most important environmental transformation in history may have been the first permanent rise of atmospheric oxygen around 2.3 Ga. Before this Great Oxidation Event (GOE), Earth's atmosphere and oceans were virtually devoid of this gas, which forms the basis for all macroscopic life. Yet full oxygenation was a long, drawn out process. This talk will lay out the state-of-the-art in our understanding of Earth's early oxygenation, with an emphasis on the delay between the first biological oxygen production, tentatively placed at 3 Ga, and the appearance of animals almost 2.5 billion years later. Recent work suggests transient oxygenation episodes occurred prior to the GOE. Once permanently present in the atmosphere, oxygen may have risen to very high levels and then nose-dived. Then, at least a billion years of dominantly oxygen-free conditions in the deep ocean followed, beneath an atmosphere and shallow oceans much leaner in oxygen than previous estimates indicated. Deficiencies in oxygen and associated nutrients may have, in turn, set a challenging course for many of the oceans' inhabitants, explaining persistently low populations and diversities of eukaryotes. The latest data suggest these billion-plus years of intermediate oxygen were followed by increases in both ocean and atmosphere oxygen contents and eukaryotic diversity 750 to 800 million years ago. Novel, rock-bound proxies and complementary numerical models are now steering our views of co-evolving life and marine and atmospheric chemistry, including greenhouse gas controls on climate. New findings are revealing various states of planetary habitability that differ greatly from the Earth we know today. These

  18. Impact shocked rocks as protective habitats on an anoxic early Earth

    Science.gov (United States)

    Bryce, Casey C.; Horneck, Gerda; Rabbow, Elke; Edwards, Howell G. M.

    2015-01-01

    On Earth, microorganisms living under intense ultraviolet (UV) radiation stress can adopt endolithic lifestyles, growing within cracks and pore spaces in rocks. Intense UV irradiation encountered by microbes leads to death and significant damage to biomolecules, which also severely diminishes the likelihood of detecting signatures of life. Here we show that porous rocks shocked by asteroid or comet impacts provide protection for phototrophs and their biomolecules during 22 months of UV radiation exposure outside the International Space Station. The UV spectrum used approximated the high-UV flux on the surface of planets lacking ozone shields such as the early Earth. These data provide a demonstration that endolithic habitats can provide a refugium from the worst-case UV radiation environments on young planets and an empirical refutation of the idea that early intense UV radiation fluxes would have prevented phototrophs without the ability to form microbial mats or produce UV protective pigments from colonizing the surface of early landmasses.

  19. Exposure of phototrophs to 548 days in low Earth orbit: microbial selection pressures in outer space and on early earth.

    Science.gov (United States)

    Cockell, Charles S; Rettberg, Petra; Rabbow, Elke; Olsson-Francis, Karen

    2011-10-01

    An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated with the natural community survived. Of the augmented organisms, cells of A. cylindrica and Chroococcidiopsis survived, but no cells of N. commune. Only cells of Chroococcidiopsis were cultured from samples exposed to the unattenuated extraterrestrial ultraviolet (UV) spectrum (>110 nm or 200 nm). Raman spectroscopy and bright-field microscopy showed that under these conditions the surface cells were bleached and their carotenoids were destroyed, although cell morphology was preserved. These experiments demonstrate that outer space can act as a selection pressure on the composition of microbial communities. The results obtained from samples exposed to >200 nm UV (simulating the putative worst-case UV exposure on the early Earth) demonstrate the potential for epilithic colonization of land masses during that time, but that UV radiation on anoxic planets can act as a strong selection pressure on surface-dwelling organisms. Finally, these experiments have yielded new phototrophic organisms of potential use in biomass and oxygen production in space exploration.

  20. A Reducing Atmosphere From Out-gassing of the Early Earth

    Science.gov (United States)

    Schaefer, L.; Fegley, B., Jr.

    2005-08-01

    Earth's present atmosphere originated from out-gassing of volatile-bearing grains. We calculated the composition of volatiles out-gassed from chondritic planetary bodies. We present results for average CI, CM, CV, H, L, and EH chondrites, which are the building blocks of the Earth. From the oxygen-isotope mixing (OIM) model, we calculated a composition of 70% EH, 21% H, 5% CV, and 4% CI chondritic matter for the early Earth. The major out-gassed volatiles for these starting compositions are CH4, N2, NH3, H2, and H2O. The Miller-Urey experiment demonstrated that a reducing atmosphere like this generates amino acids and other organic compounds that are essential for the formation of life. This work is supported by the NASA Astrobiology Program. \\leavevmode \\epsfxsize=0.9\\hsize \\epsfbox{49.eps}

  1. Meteors as a Delivery Vehicle for Organic Matter to the Early Earth

    Science.gov (United States)

    Jenniskens, Peter; DeVincenzi, D. (Technical Monitor)

    2001-01-01

    Only in recent years has a concerted effort been made to study the circumstances under which extraterrestrial organic matter is accreted on Earth by way of meteors. Meteors are the luminous phenomena associated with the (partial) ablation of meteoric matter and represent the dominant pathway from space to Earth, with the possible exception of rare giant impacts of asteroids and comets. Meteors dominated the supply of organics to the early Earth if organic matter survived this pathway efficiently. Moreover, meteors are a source of kinetic energy that can convert inert atmospheric gases such as CO, N, and H2O into useful compounds, such as HCN and NO. Understanding these processes relies heavily on empirical evidence that is still very limited. Here I report on the observations in hand and discuss their relevance in the context of the origin of life.

  2. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  3. The Bombardment of the Earth During the Hadean and Early Archean Eras

    Science.gov (United States)

    Marchi, S.; Bottke, W. F.; Elkins-Tanton, L. T.; Morbidelli, A.; Wuennemann, K.; Kring, D. A.; Bierhaus, M.

    2013-12-01

    Our knowledge of the Earth during the Hadean and early Archean eons (ca 4.5-3.5 Ga) is very limited, mainly because few rocks older than 3.8 Ga have been found (e.g. Harrison 2009). Hadean-era zircons have allowed us to glean important insights into this era, but their data has led to considerably different evolution models for the evolution of the early Earth; some predict a hellish world dominated by a molten surface with a sporadic steam atmosphere (e.g. Pollack 1997), while others have predicted a tranquil, cool surface with stable oceans (e.g. Wilde et al 2001; Valley et al 2002). To understand whether either model (or both) could be right, we believe it is useful to quantitatively examine the post Moon-forming impact bombardment of the early Earth. Over the last several years, through a combination of observations (e.g., Marchi et al 2012), theoretical models (e.g., Bottke et al 2012), and geochemical constraints from lunar rock (e.g. highly siderophile elements -HSE- abundances delivered to the Moon by impactors; the global number of lunar basins; the record of Archean-era impact spherule beds on Earth; Walker 2009; Neumann et al 2012), we have constructed a calibrated model of the early lunar impactor flux (Morbidelli et al 2012). Our results have now been extrapolated to the Earth, where they can make predictions about its early bombardment. Using a Monte Carlo code to account for the stochastic nature of major impacts, and constraining our results by the estimated HSE abundances of Earth's mantle (that were presumably delivered by impactors; Walker 2009; Bottke et al. 2010), we find the following trends. In the first ~100-200 Myr after the formation of the Moon, which we assume was created ~4.5 Ga, the Earth was almost entirely resurfaced by impacts. This bombardment, which included numerous D > 1000 km diameter impactors, should have vigorously mixed the crust and upper mantle. Between ~4.1-4.3 Ga, the impactor flux steadily decreased; though an uptick

  4. The not-so-sublime early Earth recorded in Hadean zircons

    Science.gov (United States)

    Cavosie, A. J.

    2011-12-01

    The first few hundred million years following accretion is the least understood eon in the geologic time scale- the Hadean. This poorly defined eon continues to both challenge and fascinate scientists seeking to understand the early Earth, as the most profound planet-wide transition in Earth history occurred during the Hadean: the post-accretion transformation from a meteorite impact dominated, partially molten, steam covered mafic surface on a 'Hot Earth', to a solidified, granitoid-bearing, water covered, life-supporting 'Cool Earth'. Intact rocks from the Hadean have not been identified; other means are thus required to study early Earth processes, such as the appearance, formation, and processing of evolved crust, duration of early impacts and magma oceans, the appearance of liquid water and oceans, and ultimately, stabilization of habitats for life. Hadean detrital zircons found in younger sedimentary rocks in Australia, China, and the USA constitute a mineral record from the early Earth that enables 'ground truth' constraints to be placed on early Earth processes. Hadean zircons are complicated and originate from myriad sources; identification of grains that preserve magmatic composition is critical (as evidenced by growth zoning in CL, concordant U-Pb systematics, trace element abundances and ratios), as many have been modified by secondary processes. Detailed documentation of analyzed material is paramount. A generally consistent understanding of processes on the Hadean Earth is emerging, based on data from well-documented igneous zircons with concordant U-Pb systems: (1) A record of continuous magmatism and rock-forming events starting at 4.4 Ga is recorded in U-Pb ages of Hadean zircons; no periods of magmatic quiescence occur in the Hadean. (2) Coupled Lu/Hf and U/Pb data require formation of evolved crust from extracted Hadean reservoirs by 4.5 to 4.4 Ga. (3) Mineral inclusion suites, low Ti and high Li abundances, trace elements (U-Yb), and elevated

  5. An early geodynamo driven by exsolution of mantle components from Earth's core.

    Science.gov (United States)

    Badro, James; Siebert, Julien; Nimmo, Francis

    2016-08-18

    Recent palaeomagnetic observations report the existence of a magnetic field on Earth that is at least 3.45 billion years old. Compositional buoyancy caused by inner-core growth is the primary driver of Earth's present-day geodynamo, but the inner core is too young to explain the existence of a magnetic field before about one billion years ago. Theoretical models propose that the exsolution of magnesium oxide--the major constituent of Earth's mantle--from the core provided a major source of the energy required to drive an early dynamo, but experimental evidence for the incorporation of mantle components into the core has been lacking. Indeed, terrestrial core formation occurred in the early molten Earth by gravitational segregation of immiscible metal and silicate melts, transporting iron-loving (siderophile) elements from the silicate mantle to the metallic core and leaving rock-loving (lithophile) mantle components behind. Here we present experiments showing that magnesium oxide dissolves in core-forming iron melt at very high temperatures. Using core-formation models, we show that extreme events during Earth's accretion (such as the Moon-forming giant impact) could have contributed large amounts of magnesium to the early core. As the core subsequently cooled, exsolution of buoyant magnesium oxide would have taken place at the core–mantle boundary, generating a substantial amount of gravitational energy as a result of compositional buoyancy. This amount of energy is comparable to, if not more than, that produced by inner-core growth, resolving the conundrum posed by the existence of an ancient magnetic field prior to the formation of the inner core.

  6. Impact melting of frozen oceans on the early Earth: implications for the origin of life

    Science.gov (United States)

    Bada, J. L.; Bigham, C.; Miller, S. L.

    1994-01-01

    Without sufficient greenhouse gases in the atmosphere, the early Earth would have become a permanently frozen planet because the young Sun was less luminous than it is today. Several resolutions to this faint young Sun-frozen Earth paradox have been proposed, with an atmosphere rich in CO2 being the one generally favored. However, these models assume that there were no mechanisms for melting a once frozen ocean. Here we show that bolide impacts between about 3.6 and 4.0 billion years ago could have episodically melted an ice-covered early ocean. Thaw-freeze cycles associated with bolide impacts could have been important for the initiation of abiotic reactions that gave rise to the first living organisms.

  7. Isotopic constraints on the age and early differentiation of the Earth.

    Science.gov (United States)

    McCulloch, M T

    1996-03-01

    The Earth's age and early differentiation history are re-evaluated using updated isotopic constraints. From the most primitive terrestrial Pb isotopic compositions found at Isua Greenland, and the Pilbara of Western Australia, combined with precise geochronology of these localities, an age 4.49 +/- 0.02 Ga is obtained. This is interpreted as the mean age of core formation as U/Pb is fractionated due to sequestering of Pb into the Earth's core. The long-lived Rb-Sr isotopic system provides constraints on the time interval for the accretion of the Earth as Rb underwent significant depletion by volatile loss during accretion of the Earth or its precursor planetesimals. A primitive measured 87Sr/86Sr initial ratio of 0.700502 +/- 10 has been obtained for an early Archean (3.46 Ga) barite from the Pilbara Block of Western Australia. Using conservative models for the evolution of Rb/Sr in the early Archean mantle allows an estimate to be placed on the Earth's initial Sr ratio at approximately 4.50 Ga, of 0.69940 +/- 10. This is significantly higher than that measured for the Moon (0.69900 +/- 2) or in the achondrite, Angra dos Reis (0.69894 +/- 2) and for a Rb/Sr ratio of approximately 1/2 of chondrites corresponds to a mean age for accretion of the Earth of 4.48 + /- 0.04 Ga. The now extinct 146Sm-142Nd (T1/2(146)=103 l0(6)yrs) combined with the long-lived 147Sm-143Nd isotopic systematics can also be used to provide limits on the time of early differentiation of the Earth. High precision analyses of the oldest (3.8-3.9 Ga) Archean gneisses from Greenland (Amitsoq and Akilia gneisses), and Canada (Acasta gneiss) do not show measurable (> +/- l0ppm) variations of 142Nd, in contrast to the 33 ppm 142Nd excess reported for an Archean sample. The general lack of 142Nd variations, combined with the presence of highly positive epsilon 143 values (+4.0) at 3.9 Ga, indicates that the record of large-scale Sm/Nd fractionation events was not preserved in the early-Earth from 4

  8. Young Sun, Early Earth and the Origins of Life Lessons for Astrobiology

    CERN Document Server

    Gargaud, Muriel; López-García, Purificación; Montmerle, Thierry; Pascal, Robert

    2012-01-01

    - How did the Sun come into existence? - How was the Earth formed? - How long has Earth been the way it is now, with its combination of oceans and continents? - How do you define “life”? - How did the first life forms emerge? - What conditions made it possible for living things to evolve? All these questions are answered in this colourful textbook addressing undergraduate students in "Origins of Life" courses and the scientifically interested public. The authors take the reader on an amazing voyage through time, beginning five thousand million years ago in a cloud of interstellar dust and ending five hundred million years ago, when the living world that we see today was finally formed. A chapter on exoplanets provides an overview of the search for planets outside the solar system, especially for habitable ones. The appendix closes the book with a glossary, a bibliography of further readings and a summary of the Origins of the Earth and life in fourteen boxes.

  9. Alkali element depletion by core formation and vaporization on the early Earth

    Science.gov (United States)

    Lodders, K.; Fegley, B., Jr.

    1994-01-01

    The depletion of Na, K, Rb, and Cs in the Earth's upper mantle and crust relative to their abundances in chondrites is a long standing problem in geochemistry. Here we consider two commonly invoked mechanisms, namely core formation, and vaporization, for producing the observed depletions. Our models predict that a significant percentage of the Earth's bulk alkali element inventory is in the core (30 percent for Na, 52 percent for K, 74 percent for Rb, and 92 percent for Cs). These predictions agree with independent estimates from nebular volatility trends and (for K) from terrestrial heat flow data. Our models also predict that vaporization and thermal escape during planetary accretion are unlikely to produce the observed alkali element depletion pattern. However, loss during the putative giant impact which formed the Moon cannot be ruled out. Experimental, observational, and theoretical tests of our predictions are also described. Alkali element partitioning into the Earth's core was modeled by assuming that alkali element partitioning during core formation on the aubrite parent body (APB) is analogous to that on the early Earth. The analogy is reasonable for three reasons. First, the enstatite meteorites are the only known meteorites with the same oxygen isotope systematics as the Earth-Moon system. Second, the large core size of the Earth and the V depletion in the mantle requires accretion from planetesimals as reduced as the enstatite chondrites. Third, experimental studies of K partitioning between silicate and metal plus sulfide show that more K goes into the metal plus sulfide at higher pressures than at one atmosphere pressure. Thus partitioning in the relatively low pressure natural laboratory of the APB is a good guide to alkali elemental partitioning during the growth of the Earth.

  10. Early Earth tectonics: A high-resolution 3D numerical modelling approach

    Science.gov (United States)

    Fischer, R.; Gerya, T.

    2014-12-01

    Early Earth had a higher amount of remaining radiogenic elements as well as a higher amount of leftover primordial heat. Both contributed to the increased temperature in the Earth's interior and it is mainly this increased mantle potential temperature ΔTp that controls the dynamics of the crust and upper mantle and the style of Early Earth tectonics. For a minor increase in temperature ΔTp buckling, delamination and Rayleigh-Taylor style dripping of the plate is observed in addition. For higher temperatures ΔTp > 250 K no subduction can be observed anymore and tectonics is dominated by delamination and Rayleigh-Taylor instabilities. We conduct 3D petrological-thermomechanical numerical modelling experiments of the crust and upper mantle under Early Earth conditions and a plume tectonics model setup. For varying crustal structures and an increased mantle potential temperature ΔTp, a thermal anomaly in the bottom temperature boundary introduces a plume. The model is able to self-sufficiently form depleted mantle lithosphere after repeated melt removal. New crust can be produced in the form of volcanics or plutonics. To simulate differentiation the newly formed crust can have a range in composition from basaltic over dacitic to granitic depending on its source rock. Models show large amounts of subcrustal decompression melting and consequently large amounts of new formed crust which in turn influences the dynamics. Mantle and crust are convecting separately. Dome-shaped plutons of mafic or felsic composition can be observed in the crust. Between these domes elongated belts of upper crust, volcanics and sediments are formed. These structures look similar to, for example, the Kaapvaal craton in South Africa where the elongated shape of the Barberton Greenstone Belt is surrounded by multiple plutons.

  11. Plate tectonics on the early Earth: Limitations imposed by strength and buoyancy of subducted lithosphere

    Science.gov (United States)

    van Hunen, Jeroen; van den Berg, Arie P.

    2008-06-01

    The tectonic style and viability of modern plate tectonics in the early Earth is still debated. Field observations and theoretical arguments both in favor and against the uniformitarian view of plate tectonics back until the Archean continue to accumulate. Here, we present the first numerical modeling results that address for a hotter Earth the viability of subduction, one of the main requirements for plate tectonics. A hotter mantle has mainly two effects: 1) viscosity is lower, and 2) more melt is produced, which in a plate tectonic setting will lead to a thicker oceanic crust and harzburgite layer. Although compositional buoyancy resulting from these thick crust and harzburgite might be a serious limitation for subduction initiation, our modeling results show that eclogitization significantly relaxes this limitation for a developed, ongoing subduction process. Furthermore, the lower viscosity leads to more frequent slab breakoff, and sometimes to crustal separation from the mantle lithosphere. Unlike earlier propositions, not compositional buoyancy considerations, but this lithospheric weakness could be the principle limitation to the viability of plate tectonics in a hotter Earth. These results suggest a new explanation for the absence of ultrahigh-pressure metamorphism (UHPM) and blueschists in most of the Precambrian: early slabs were not too buoyant, but too weak to provide a mechanism for UHPM and exhumation.

  12. Carbonaceous meteorites as a source of sugar-related organic compounds for the early Earth.

    Science.gov (United States)

    Cooper, G; Kimmich, N; Belisle, W; Sarinana, J; Brabham, K; Garrel, L

    The much-studied Murchison meteorite is generally used as the standard reference for organic compounds in extraterrestrial material. Amino acids and other organic compounds important in contemporary biochemistry are thought to have been delivered to the early Earth by asteroids and comets, where they may have played a role in the origin of life. Polyhydroxylated compounds (polyols) such as sugars, sugar alcohols and sugar acids are vital to all known lifeforms-they are components of nucleic acids (RNA, DNA), cell membranes and also act as energy sources. But there has hitherto been no conclusive evidence for the existence of polyols in meteorites, leaving a gap in our understanding of the origins of biologically important organic compounds on Earth. Here we report that a variety of polyols are present in, and indigenous to, the Murchison and Murray meteorites in amounts comparable to amino acids. Analyses of water extracts indicate that extraterrestrial processes including photolysis and formaldehyde chemistry could account for the observed compounds. We conclude from this that polyols were present on the early Earth and therefore at least available for incorporation into the first forms of life.

  13. Carbonaceous meteorites as a source of sugar-related organic compounds for the early Earth

    Science.gov (United States)

    Cooper, G.; Kimmich, N.; Belisle, W.; Sarinana, J.; Brabham, K.; Garrel, L.

    2001-01-01

    The much-studied Murchison meteorite is generally used as the standard reference for organic compounds in extraterrestrial material. Amino acids and other organic compounds important in contemporary biochemistry are thought to have been delivered to the early Earth by asteroids and comets, where they may have played a role in the origin of life. Polyhydroxylated compounds (polyols) such as sugars, sugar alcohols and sugar acids are vital to all known lifeforms-they are components of nucleic acids (RNA, DNA), cell membranes and also act as energy sources. But there has hitherto been no conclusive evidence for the existence of polyols in meteorites, leaving a gap in our understanding of the origins of biologically important organic compounds on Earth. Here we report that a variety of polyols are present in, and indigenous to, the Murchison and Murray meteorites in amounts comparable to amino acids. Analyses of water extracts indicate that extraterrestrial processes including photolysis and formaldehyde chemistry could account for the observed compounds. We conclude from this that polyols were present on the early Earth and therefore at least available for incorporation into the first forms of life.

  14. Planetary Temperatures : Early Estimates, Lowell, and the Albedo of the Earth

    Science.gov (United States)

    Lorenz, Ralph

    2016-10-01

    While it was recognized by Huygens, as soon as the architecture of the solar system was understood, that outer planets would be much cooler than Earth, quantitative estimation of planetary temperatures only became possible with understanding of radiant heat, and specifically the Stefan law relating heat flux to the fourth power of absolute temperature. This relation appears to have been first applied to planetary temperatures by the Danish physicist Christiansen in 1885, and he derived results for Mars and Saturn of -40 and -180C, rather reasonable values. However, the separate values of the solar constant, absolute planetary albedos (including that of the Earth) and the short- and long-wave transparency of planetary atmospheres were not known, although mountaintop measurements by Langley made some first steps to quantifying these effects. Lowell recognized that the Martian atmosphere was thinner than ours, but had more carbon dioxide, and so considered these factors to cancel out. However, he suggested that the Earth had a reflectivity of some 75%, such that darker Mars would absorb a larger fraction of incident sunlight than the Earth, compensating for Mars' greater distance from the sun and thus allowing clement temperatures. It is difficult not to see this as pushing the numbers to obtain a desired result, and indeed a robust refutation of his calculations swiftly followed by Poynting and Alfred Russel Wallace. I present a brief review of these early days of planetary climate modeling.

  15. Early Earth melt production in a subduction zone, a petrological model

    Science.gov (United States)

    Magni, V.; Bouilhol, P.; Van Hunen, J.; Moyen, J.

    2013-12-01

    A large part of the Archean continental crust is made of a composite rock assemblage dominated by granitoids belonging to the TTG series (tonalite-trondhejmeite-granodiorite). The modus operandi of this sodic granitoids still disputed. If the modern processes leading to continental crust formation at convergent margins are well constrained, the extrapolation to early Earth conditions is hazardous, because the composition of Earth's early crust can be achieved through several processes. However, an 'arc' signature seems to be present in TTGs, suggesting a formation of continental crust in subduction zone settings. Moreover, they show strong similarities with modern adakites, which are thought to be formed by melting of the oceanic subducting crust. We present the results of a study where numerical models of subduction are integrated with a thermodynamic database. Our goal is to investigate under which conditions slab melting can be achieved if at all. We particularly focus our attention on the fate of water, since it is a component that is essential to the formation of TTG series, independently of the petrogenetical scenario preferred. The amount and composition of water bearing fluids in a subduction zone is controlled by slab devolatilization, and influence both the melting regime and the melt composition. Our reference model of an early Earth regime, with a high mantle potential temperature, show that the slab dehydrates early, ending up being composed of a dry eclogites. Importantly, our models show that dehydration melting is not achieved in the slab crust; yet, water-present melting of the 'dry' eclogites can be achieved if a dehydration reaction occurs in the deeper portion of the slab, fuelling the melting reaction with water. Moreover, the dehydration reactions that occurred within the slab are able to metasomatize the overlying mantle wedge, forming hydrated peridotites, that becomes a melt source when dragged down by corner-flow. Our results show the

  16. Lipid biomarker production and preservation in acidic ecosystems: Relevance to early Earth and Mars

    Science.gov (United States)

    Jahnke, L. L.; Parenteau, M. N.; Harris, R.; Bristow, T.; Farmer, J. D.; Des Marais, D. J.

    2013-12-01

    Compared to relatively benign carbonate buffered marine environments, terrestrial Archean and Paleoproterozoic life was forced to cope with a broader range of pH values. In particular, acidic terrestrial ecosystems arose from the oxidation of reduced species in hydrothermal settings and crustal reservoirs of metal sulfides, creating acid sulfate conditions. While oxidation of reduced species is facilitated by reactions with molecular oxygen, acidic conditions also arose in Archean hydrothermal systems before the rise of oxygen (Van Kranendonk, 2006), expanding the range of time over which acidophiles could have existed on the early Earth. Acidic terrestrial habitats would have included acidic hydrothermal springs, acid sulfate soils, and possibly lakes and streams lacking substantial buffering capacity with sources of acidity in their catchments. Although acidic hot springs are considered extreme environments on Earth, robust and diverse microbial communities thrive in these habitats. Such acidophiles are found across all three domains of life and include both phototrophic and chemotrophic members. In this presentation, we examine hopanes and sterols that are characteristic of microbial communities living in acidic hydrothermal environments. Moreover we discuss taphonomic processes governing the capture and preservation of these biosignatures in acid environments. In particular, we discuss the production and early preservation of hopanoids and sterols in the following geological/mineralogical settings: 1) rapid entombment of microbes and organic matter by predominantly fine-grained silica; 2) rapid burial of organic matter by clay-rich, silica poor sediments; 3) and the survival of organics in iron oxide and sulfate rich sediments. We discovered and isolated an acid-tolerant purple non-sulfur anoxygenic phototroph from Lassen Volcanic National Park that synthesizes 3methyl-bacteriohopanepolyols. These compounds were previously thought to be exclusively made by

  17. Reactive Oxygen Species on the Early Earth and Survival of Bacteria

    Science.gov (United States)

    Balk, Melikea; Mason, Paul; Stams, Alfons J. M.; Smidt, Hauke; Freund, Friedemann; Rothschild, Lynn

    2011-01-01

    An oxygen-rich atmosphere appears to have been a prerequisite for complex, multicellular life to evolve on Earth and possibly elsewhere in the Universe. However it remains unclear how free oxygen first became available on the early Earth. A potentially important, and as yet poorly constrained pathway, is the production of oxygen through the weathering of rocks and release into the near-surface environment. Reactive Oxygen Species (ROS), as precursors to molecular oxygen, are a key step in this process, and may have had a decisive impact on the evolution of life, present and past. ROS are generated from minerals in igneous rocks during hydrolysis of peroxy defects, which consist of pairs of oxygen anions oxidized to the valence state -1 and during (bio) transformations of iron sulphide minerals. ROS are produced and consumed by intracellular and extracellular reactions of Fe, Mn, C, N, and S species. We propose that, despite an overall reducing or neutral oxidation state of the macroenvironment and the absence of free O2 in the atmosphere, organisms on the early Earth had to cope with ROS in their microenvironments. They were thus under evolutionary pressure to develop enzymatic and other defences against the potentially dangerous, even lethal effects of oxygen and its derived ROS. Conversely it appears that microorganisms learned to take advantage of the enormous reactive potential and energy gain provided by nascent oxygen. We investigate how oxygen might be released through weathering. We test microorganisms in contact with rock surfaces and iron sulphides. We model bacteria such as Deionococcus radiodurans and Desulfotomaculum, Moorella and Bacillus species for their ability to grow or survive in the presence of ROS. We examine how early Life might have adapted to oxygen.

  18. Synthesis of nitrous oxide by lightning in the early anoxic Earth's atmosphere

    Science.gov (United States)

    Navarro, K. F.; Navarro-Gonzalez, R.; McKay, C. P.

    2013-12-01

    Carbon dioxide (CO2) was the main atmospheric component of the early Earth's atmosphere and exerted a key role in climate by maintaining a hydrosphere during a primitive faint Sun [1]; however, CO2 was eventually removed from the atmosphere by rock weathering and sequestered in the Earth's crust and mantle [1]. Nitric oxide (NO) was fixed by lightning discharges at a rate of 1×1016 molecules J-1 in CO2 (50-80%) rich atmospheres [2]. As the levels of atmospheric CO2 dropped to 20%, the production rate of NO by lightning rapidly decreased to 2×1014 molecules J-1 and then slowly diminished to 1×1014 molecules J-1 at CO2 levels of about 2.5% [2]. In order to maintain the existence of liquid water in the early Earth, it is required to warm up the planet with other greenhouse gases such as methane (CH4) [3]. Here we report an experimental study of the effects of lightning discharges on the nitrogen fixation rate during the evolution of the Earth's early atmosphere from 10 to 0.8 percent of carbon dioxide with methane concentrations from 0 to 1,000 ppm in molecular nitrogen. Lightning was simulated in the laboratory by a plasma generated with a pulsed Nd-YAG laser [2]. Our results show that the production of NO by lightning is independent of the presence of methane but drops from 3×1014 molecules J-1 in 10% CO2 to 5×1013 molecules J-1 in 1% CO2. Surprisingly, nitrous oxide (N2O) is also produced at a rate of 4×1013 molecules J-1 independent of the levels of CH4 and CO2. N2O is produced by lightning in the contemporaneous oxygenated Earth's atmosphere at a comparable rate of (0.4-1.5)×1013 molecules J-1 [4, 5], but was not detected in nitrogen-carbon dioxide mixtures in the absence of oxygen [6]. The only previously reported abiotic synthesis of N2O was by corona discharges in rich CO2 atmospheres (20-80%) with a production rate of 8×1012 molecules J-1 [6]; however at lower CO2 (atmosphere was the main source of N2O in nitrogen dominated atmospheres. N2O is not

  19. A review of noble gas geochemistry in relation to early Earth history

    Science.gov (United States)

    Kurz, M. D.

    1985-01-01

    One of the most fundamental noble gas constraints on early Earth history is derived from isotopic differences in (129)Xe/(130)Xe between various terrestrial materials. The short half life (17 m.y.) of extinct (129I, parent of (129)Xe, means that these differences must have been produced within the first 100 m.y. after terrestrial accretion. The identification of large anomalies in (129)Xe/(130)Xe in mid ocean ridge basalts (MORB), with respect to atmospheric xenon, suggests that the atmosphere and upper mantle have remained separate since that time. This alone is a very strong argument for early catastrophic degassing, which would be consistent with an early fractionation resulting in core formation. However, noble gas isotopic systematics of oceanic basalts show that the mantle cannot necessarily be regarded as a homogeneous system, since there are significant variations in (3)He/(4)He, (40)Ar/(36)Ar, and (129)Xe/(130)Xe. Therefore, the early degassing cannot be considered to have acted on the whole mantle. The specific mechanisms of degassing, in particular the thickness and growth of the early crust, is an important variable in understanding present day noble gas inventories. Another constraint can be obtained from rocks that are thought to be derived from near the lithosphere asthenosphere boundary: ultramafic xenoliths.

  20. What traces of life can we expect on Mars? Lessons from the early Earth

    Science.gov (United States)

    Westall, F.

    2008-09-01

    Abstract Environmental conditions on early Mars, from a microbial point of view, were largely similar to those on the early Earth. The oldest, well-preserved rocks on the early Earth (~3.5 Ga) host a wide range of morphological and geochemical traces of life, including chemolithotrophic, heterotrophic and photosynthetic anaerobic microorganisms. These microorganisms evolved in a tectonically evolving geological context, including carbonate platform formation. This scenario did not exist on Mars. Moreover, Mars was outside the habitable zone and standing bodies of water were probably ice-covered. Evolutionary advancement of martian life (if it appeared) would have been curtailed very early and it is unlikely that photosynthesis could have evolved. It is therefore unlikely that martian life will leave visible traces that can be detected with in situ instrumentation (no biolaminites or stromatolites). Geochemical detection of organic components will be possible but it is unlikely that the results will be conclusive. The return of suitable rocks from Mars is advocated. Early life on Earth and Mars The oldest, well preserved rocks on Earth, including both sedimentary and volcanic lithologies, contain abundant morphological and geochemical traces of life [1]. Evidence of borings into basalt lavas [2] and microbial colonies within volcanic sediments [3,4] testify to microbial utilisation of chemolithotrophy. Microscopic tunnels, tens of microns in length, containing traces of biologically important elements, such as C and N, in the vitreous rinds of pillow lavas are identified in petrographic thin section (Fig. 1) [2]. Similar 5-10 μm-sized tunnels have been channelled into the surfaces of detrital volcanic grains [4]. They contain the remains of microbial polymeric substances (EPS) but can only be identified in petrographic thin section and using the high magnification of a scanning electron microscope (SEM). Furthermore, volcanic sediments deposited in water contain

  1. Life might be rare despite its early emergence on Earth: a Bayesian analysis of the probability of abiogenesis

    CERN Document Server

    Spiegel, David S

    2011-01-01

    Life arose on Earth sometime in the first few hundred million years after the young planet had cooled to the point that it could support water-based organisms on its surface. The early emergence of life on Earth has been taken as evidence that the probability of abiogenesis is high, if starting from young-Earth-like conditions. We revisit this argument quantitatively in a Bayesian statistical framework. By constructing a simple model of the probability of abiogenesis, we calculate a Bayesian estimate of its posterior probability, given the data that life emerged fairly early in Earth's history and that, billions of years later, sentient creatures noted this fact and considered its implications. We find that, given only this very limited empirical information, the choice of Bayesian prior for the abiogenesis probability parameter has a dominant influence on the computed posterior probability. Thus, although life began on this planet fairly soon after the Earth became habitable, this fact is consistent with an ...

  2. Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model

    Science.gov (United States)

    Gebauer, S.; Grenfell, J. L.; Stock, J. W.; Lehmann, R.; Godolt, M.; von Paris, P.; Rauer, H.

    2017-01-01

    Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O2, whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis. The O2 bistability found by Goldblatt et al. (2006) is not observed in our calculations likely due to our detailed CH4 oxidation scheme. We calculate increased CH4 with increasing O2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O2 is unique. Mixing, CH4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O2 fluxes. Regarding exoplanets, different "states" of O2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases remove O2 that

  3. Petrochronology in constraining early Archean Earth processes and environments: Barberton greenstone belt, South Africa

    Science.gov (United States)

    Grosch, Eugene

    2017-04-01

    Analytical and petrological software developments over the past decade have seen rapid innovation in high-spatial resolution petrological techniques, for example, laser-ablation ICP-MS, secondary ion microprobe (SIMS, nano-SIMS), thermodynamic modelling and electron microprobe microscale mapping techniques (e.g. XMapTools). This presentation will focus on the application of petrochronology to ca. 3.55 to 3.33 billion-year-old metavolcanic and sedimentary rocks of the Onverwacht Group, shedding light on the earliest geologic evolution of the Paleoarchean Barberton greenstone belt (BGB) of South Africa. The field, scientific drilling and petrological research conducted over the past 8 years, aims to illustrate how: (a) LA-ICP-MS and SIMS U-Pb detrital zircon geochronology has helped identify the earliest tectono-sedimentary basin and sediment sources in the BGB, as well as reconstructing geodynamic processes as early as ca. 3.432 billion-years ago; (b) in-situ SIMS multiple sulphur isotope analysis of sulphides across various early Archean rock units help to reconstruct atmospheric, surface and subsurface environments on early Archean Earth and (c) the earliest candidate textural traces for subsurface microbial life can be investigated by in-situ LA-ICP-MS U-Pb dating of titanite, micro-XANES Fe-speciation analysis and metamorphic microscale mapping. Collectively, petrochronology combined with high-resolution field mapping studies, is a powerful multi-disciplinary approach towards deciphering petrogenetic and geodynamic processes preserved in the Paleoarchean Barberton greenstone belt of South Africa, with implications for early Archean Earth evolution.

  4. Evolution of Earth-like Extrasolar Planetary Atmospheres: Assessing the Atmospheres and Biospheres of Early Earth Analog Planets with a Coupled Atmosphere Biogeochemical Model.

    Science.gov (United States)

    Gebauer, S; Grenfell, J L; Stock, J W; Lehmann, R; Godolt, M; von Paris, P; Rauer, H

    2017-01-01

    Understanding the evolution of Earth and potentially habitable Earth-like worlds is essential to fathom our origin in the Universe. The search for Earth-like planets in the habitable zone and investigation of their atmospheres with climate and photochemical models is a central focus in exoplanetary science. Taking the evolution of Earth as a reference for Earth-like planets, a central scientific goal is to understand what the interactions were between atmosphere, geology, and biology on early Earth. The Great Oxidation Event in Earth's history was certainly caused by their interplay, but the origin and controlling processes of this occurrence are not well understood, the study of which will require interdisciplinary, coupled models. In this work, we present results from our newly developed Coupled Atmosphere Biogeochemistry model in which atmospheric O2 concentrations are fixed to values inferred by geological evidence. Applying a unique tool (Pathway Analysis Program), ours is the first quantitative analysis of catalytic cycles that governed O2 in early Earth's atmosphere near the Great Oxidation Event. Complicated oxidation pathways play a key role in destroying O2, whereas in the upper atmosphere, most O2 is formed abiotically via CO2 photolysis. The O2 bistability found by Goldblatt et al. ( 2006 ) is not observed in our calculations likely due to our detailed CH4 oxidation scheme. We calculate increased CH4 with increasing O2 during the Great Oxidation Event. For a given atmospheric surface flux, different atmospheric states are possible; however, the net primary productivity of the biosphere that produces O2 is unique. Mixing, CH4 fluxes, ocean solubility, and mantle/crust properties strongly affect net primary productivity and surface O2 fluxes. Regarding exoplanets, different "states" of O2 could exist for similar biomass output. Strong geological activity could lead to false negatives for life (since our analysis suggests that reducing gases remove O2 that

  5. Records of our Early Biosphere Illuminate our Origins and Guide our Search for Life Beyond Earth

    Science.gov (United States)

    DesMarais, David J.

    2003-01-01

    A scientific "mission of exploration to early Earth" will help us chart the distribution of life elsewhere. We must discriminate between attributes of biospheres that are universal versus those attributes that represent principally the outcomes of long-term survival specifically on Earth. In addition to the basic physics and chemistry of matter, the geologic evolution of rocky habitable planets and their climates might be similar elsewhere in the Universe. Certain key agents that drive long-term environmental change (e.g., stellar evolution, impacts, geothermal heat flow, tectonics, etc.) can help us to reconstruct ancient climates and to compare their evolution among populations of Earth- like planets. Early Earth was tectonically more active than today and therefore it exhaled reduced chemical species into the more oxidized surface environment at greater rates. This tectonic activity thus sustained oxidation-reduction reactions that provided the basis for the development of biochemical pathways that harvest chemical energy ("bioenergetics"). Most examples of bioenergetics today that extract energy by reacting oxidized and reduced chemicals in the environment were likely more pervasive among our microbial ancestors than are the presently known examples of photosynthesis. The geologic rock record indicates that, as early as 3.5 billion years ago (3.5 Ga), microbial biofilms were widespread within the coastal environments of small continents and tectonically unstable volcanic islands. Non oxygen-producing (non-oxygenic) photosynthesis preceded oxygenic photosynthesis, but all types of photosynthesis contributed substantially to the long-term increase in global primary biological productivity. Evidence of photosynthesis is tentative by 3.5 Ga and compelling by 2.7 Ga. Evidence of oxygenic photosynthesis is strong by 2.7 Ga and compelling by 2.3 Ga. These successive innovations transformed life from local communities that survived principally by catalyzing chemical

  6. Early Earth plume-lid tectonics: A high-resolution 3D numerical modelling approach

    Science.gov (United States)

    Fischer, R.; Gerya, T.

    2016-10-01

    Geological-geochemical evidence point towards higher mantle potential temperature and a different type of tectonics (global plume-lid tectonics) in the early Earth (>3.2 Ga) compared to the present day (global plate tectonics). In order to investigate tectono-magmatic processes associated with plume-lid tectonics and crustal growth under hotter mantle temperature conditions, we conduct a series of 3D high-resolution magmatic-thermomechanical models with the finite-difference code I3ELVIS. No external plate tectonic forces are applied to isolate 3D effects of various plume-lithosphere and crust-mantle interactions. Results of the numerical experiments show two distinct phases in coupled crust-mantle evolution: (1) a longer (80-100 Myr) and relatively quiet 'growth phase' which is marked by growth of crust and lithosphere, followed by (2) a short (∼20 Myr) and catastrophic 'removal phase', where unstable parts of the crust and mantle lithosphere are removed by eclogitic dripping and later delamination. This modelling suggests that the early Earth plume-lid tectonic regime followed a pattern of episodic growth and removal also called episodic overturn with a periodicity of ∼100 Myr.

  7. Looking Backwards in Time to the Early Earth Using the Lens of Stable Isotope Geodynamic Cycles

    Science.gov (United States)

    Gregory, R. T.

    2016-12-01

    The stable isotope ratios of hydrogen, carbon, oxygen and sulfur provide of means of tracing interactions between the major reservoirs of the Earth. The oceans and the dichotomy between continental and oceanic crust are key differences between the Earth and other terrestrial bodies. The existence of plate tectonics and the recognition that no primary crust survives at the Earth's surface sets this planet apart from the smaller terrestrial bodies. The thermostatic control of carbonate-silicate cycle works because of the hydrosphere and plate tectonics. Additionally, the contrast between the carbon isotope ratios for reduced and oxidized species appear to also be invariant over geologic time with evidence of old recycled carbon in the form of diamond inclusions in mantle-derived igneous rocks. Lessons from comparative planetology suggest that early differentiation of the Earth would have likely resulted in the rapid formation of the oceans, a water world over the primary crust. Plate tectonics provides a mechanism for buffering the oxygen isotope fractionation between the oceans and the mantle. The set point for hydrosphere's oxygen isotope composition is a result of the geometry of mid-ocean ridge accretion that is stable over an order magnitude change in spreading rates with time constants much younger shorter than the age of the Earth. The recognition that the "normal" ranges for hydrogen isotope ratios of igneous, metamorphic and sedimentary rocks of any age generally overlap with similar ranges, with the exception of rocks that have interacted with D- and 18O-depleted meteoric waters (generally at high latitudes), is an argument for a constant volume ocean over geologic time. Plate tectonics with a constant volume ocean constrains the thickness of the continental crust because of the rapidity of the mechanical weathering cycle (characteristic times of 10's of millions of years; freeboard of the continents argument). In a plate tectonic regime, chemical

  8. Electrochemical studies of iron meteorites: phosphorus redox chemistry on the early Earth

    Science.gov (United States)

    Bryant, David E.; Greenfield, David; Walshaw, Richard D.; Evans, Suzanne M.; Nimmo, Alexander E.; Smith, Caroline L.; Wang, Liming; Pasek, Matthew A.; Kee, Terence P.

    2009-01-01

    The mineral schreibersite, (Fe,Ni)3P, a ubiquitous component of iron meteorites, is known to undergo anoxic hydrolytic modification to afford a range of phosphorus oxyacids. H-phosphonic acid (H3PO3) is the principal hydrolytic product under hydrothermal conditions, as confirmed here by 31P-NMR spectroscopic studies on shavings of the Seymchan pallasite (Magadan, Russia, 1967), but in the presence of photochemical irradiation a more reduced derivative, H-phosphinic (H3PO2) acid, dominates. The significance of such lower oxidation state oxyacids of phosphorus to prebiotic chemistry upon the early Earth lies with the facts that such forms of phosphorus are considerably more soluble and chemically reactive than orthophosphate, the commonly found form of phosphorus on Earth, thus allowing nature a mechanism to circumvent the so-called Phosphate Problem. This paper describes the Galvanic corrosion of Fe3P, a hydrolytic modification pathway for schreibersite, leading again to H-phosphinic acid as the key P-containing product. We envisage this pathway to be highly significant within a meteoritic context as iron meteorites are polymetallic composites in which dissimilar metals, with different electrochemical potentials, are connected by an electrically conducting matrix. In the presence of a suitable electrolyte medium, i.e., salt water, galvanic corrosion can take place. In addition to model electrochemical studies, we also report the first application of the Kelvin technique to map surface potentials of a meteorite sample that allows the electrochemical differentiation of schreibersite inclusions within an Fe:Ni matrix. Such experiments, coupled with thermodynamic calculations, may allow us to better understand the chemical redox behaviour of meteoritic components with early Earth environments.

  9. Ultramafic Terranes and Associated Springs as Analogs for Mars and Early Earth

    Science.gov (United States)

    Blake, David; Schulte, Mitch; Cullings, Ken; DeVincezi, D. (Technical Monitor)

    2002-01-01

    Putative extinct or extant Martian organisms, like their terrestrial counterparts, must adopt metabolic strategies based on the environments in which they live. In order for organisms to derive metabolic energy from the natural environment (Martian or terrestrial), a state of thermodynamic disequilibrium must exist. The most widespread environment of chemical disequilibrium on present-day Earth results from the interaction of mafic rocks of the ocean crust with liquid water. Such environments were even more pervasive and important on the Archean Earth due to increased geothermal heat flow and the absence of widespread continental crust formation. The composition of the lower crust and upper mantle of the Earth is essentially the-same as that of Mars, and the early histories of these two planets are similar. It follows that a knowledge of the mineralogy, water-rock chemistry and microbial ecology of Earth's oceanic crust could be of great value in devising a search strategy for evidence of past or present life on Mars. In some tectonic regimes, cross-sections of lower oceanic crust and upper mantle are exposed on land as so-called "ophiolite suites." Such is the case in the state of California (USA) as a result of its location adjacent to active plate margins. These mafic and ultramafic rocks contain numerous springs that offer an easily accessible field laboratory for studying water/rock interactions and the microbial communities that are supported by the resulting geochemical energy. A preliminary screen of Archaean biodiversity was conducted in a cold spring located in a presently serpentinizing ultramafic terrane. PCR and phylogenetic analysis of partial 16s rRNA, sequences were performed on water and sediment samples. Archaea of recent phylogenetic origin were detected with sequences nearly identical to those of organisms living in ultra-high pH lakes of Africa.

  10. Terrestrial production vs. extraterrestrial delivery of prebiotic organics to the early Earth

    Science.gov (United States)

    Chyba, C. F.; Sagan, C.; Thomas, P. J.; Brookshaw, L.

    1991-01-01

    A comprehensive treatment of comet/asteroid interaction with the atmosphere, ensuring surface impact, and resulting organic pyrolysis is required to determine whether more than a negligible fraction of the organics in incident comets and asteroids actually survived collision with Earth. Results of such an investigation, using a smoothed particle hydrodynamic simulation of cometary and asteroidal impacts into both oceans and rock, demonstrate that organics will not survive impacts at velocities approx. greater than 10 km s(exp -1), and that even comets and asteroids as small as 100m in radius cannot be aerobraked to below this velocity in 1 bar atmospheres. However, for plausible dense (10 bar CO2) early atmospheres, there will be sufficient aerobraking during atmospheric passage for some organics to survive the ensuing impact. Combining these results with analytical fits to the lunar impact record shows that 4.5 Gyr ago Earth was accreting at least approx. 10(exp 6) kg yr(exp 1) of intact cometary organics, a flux which thereafter declined with a approx. 100 Myr half-life. The extent to which this influx was augmented by asteroid impacts, as well as the effect of more careful modelling of a variety of conservative approximations, is currently being quantified. These results may be placed in context by comparison with in situ organic production from a variety of terrestrial energy sources, as well as organic delivery by interplanetary dust. Which source dominated the early terrestrial prebiotic inventory is found to depend on the nature of the early terrestrial atmosphere. However, there is an intriguing symmetry: it is exactly those dense CO2 atmospheres where in situ atmospheric production of organic molecules should be the most difficult, in which intact cometary organics would be delivered in large amounts.

  11. Investigating the Early Atmospheres of Earth and Mars through Rivers, Raindrops, and Lava Flows

    Science.gov (United States)

    Som, Sanjoy M.

    2010-11-01

    The discovery of a habitable Earth-like planet beyond our solar-system will be remembered as one of the major breakthroughs of 21st century science, and of the same magnitude as Copernicus' heliocentric model dating from the mid 16th century. The real astrobiological breakthrough will be the added results from atmospheric remote sensing of such planets to determine habitability. Atmospheres, in both concentration and composition are suggestive of processes occurring at the planetary surface and upper crust. Unfortunately, only the modern Earth's atmosphere is known to be habitable. I investigate the density and pressure of our planet's early atmosphere before the rise of oxygen 2.5 billion years ago, because our planet was very much alive microbially. Such knowledge gives us another example of a habitable atmosphere. I also investigates the atmosphere of early Mars, as geomorphic signatures on its surface are suggestive of a past where liquid water may have present in a warmer climate, conditions suitable for the emergence of life, compared with today's 6 mbar CO2-dominated atmosphere. Using tools of fluvial geomorphology, I find that the largest river-valleys on Mars do not record a signature of a sustained hydrological cycle, in which precipitation onto a drainage basin induces many cycles of water flow, substrate incision, water ponding, and return to the atmosphere via evaporation. Rather, I conclude that while episodes of flow did occur in perhaps warmer environments, those periods were short-lived and overprinted onto a dominantly cold and dry planet. For Earth, I develop a new method of investigating atmospheric density and pressure using the size of raindrop imprints, and find that raindrop imprints preserved in the 2.7 billion year old Ventersdorp Supergroup of South Africa are consistent with precipitation falling in an atmosphere of near-surface density 0.1 kg/m3, compared to a modern value of 1.2 kg/m3, further suggesting a nitrogen level of at most

  12. Coupled orbital-thermal evolution of the early Earth-Moon system with a fast-spinning Earth

    Science.gov (United States)

    Tian, ZhenLiang; Wisdom, Jack; Elkins-Tanton, Linda

    2017-01-01

    Several new scenarios of the Moon-forming giant impact have been proposed to reconcile the giant impact theory with the recent recognition of the volatile and refractory isotopic similarities between Moon and Earth. Two scenarios leave the post-impact Earth spinning much faster than what is inferred from the present Earth-Moon system's angular momentum. The evection resonance has been proposed to drain the excess angular momentum, but the lunar orbit stays at high orbital eccentricities for long periods in the resonance, which would cause large tidal heating in the Moon. A limit cycle related to the evection resonance has also been suggested as an alternative mechanism to reduce the angular momentum, which keeps the lunar orbit at much lower eccentricities, and operates in a wider range of parameters. In this study we use a coupled thermal-orbital model to determine the effect of the change of the Moon's thermal state on the Earth-Moon system's dynamical history. The evection resonance no longer drains angular momentum from the Earth-Moon system since the system rapidly exits the resonance. Whereas the limit cycle works robustly to drain as much angular momentum as in the non-thermally-coupled model, though the Moon's tidal properties change throughout the evolution.

  13. The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

    Science.gov (United States)

    Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

    2015-01-01

    We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.

  14. Comparison of CT perfusion summary maps to early diffusion-weighted images in suspected acute middle cerebral artery stroke

    Energy Technology Data Exchange (ETDEWEB)

    Benson, John; Payabvash, Seyedmehdi [Hennepin County and University of Minnesota Medical Centers, Department of Radiology, Minneapolis, MN (United States); Salazar, Pascal [Vital Images, A Division of Toshiba Medical, Minnetonka, MN (United States); Jagadeesan, Bharathi; Palmer, Christopher S.; Truwit, Charles L. [Hennepin County and University of Minnesota Medical Centers, Department of Radiology, Minneapolis, MN (United States); McKinney, Alexander M., E-mail: mckinrad@umn.edu [Hennepin County and University of Minnesota Medical Centers, Department of Radiology, Minneapolis, MN (United States)

    2015-04-15

    Objectives: To assess the accuracy and reliability of one vendor's (Vital Images, Toshiba Medical, Minnetonka, MN) automated CT perfusion (CTP) summary maps in identification and volume estimation of infarcted tissue in patients with acute middle cerebral artery (MCA) distribution infarcts. Subjects and methods: From 1085 CTP examinations over 5.5 years, 43 diffusion-weighted imaging (DWI)-positive patients were included who underwent both CTP and DWI <12 h after symptom onset, with another 43 age-matched patients as controls (DWI-negative). Automated delay-corrected postprocessing software (DC-SVD) generated both infarct “core only” and “core + penumbra” CTP summary maps. Three reviewers independently tabulated Alberta Stroke Program Early CT scores (ASPECTS) of both CTP summary maps and coregistered DWI. Results: Of 86 included patients, 36 had DWI infarct volumes ≤70 ml, 7 had volumes >70 ml, and 43 were negative; the automated CTP “core only” map correctly classified each as >70 ml or ≤70 ml, while the “core + penumbra” map misclassified 4 as >70 ml. There were strong correlations between DWI volume with both summary map-based volumes: “core only” (r = 0.93), and “core + penumbra” (r = 0.77) (both p < 0.0001). Agreement between ASPECTS scores of infarct core on DWI with summary maps was 0.65–0.74 for “core only” map, and 0.61–0.65 for “core + penumbra” (both p < 0.0001). Using DWI-based ASPECTS scores as the standard, the accuracy of the CTP-based maps were 79.1–86.0% for the “core only” map, and 83.7–88.4% for “core + penumbra.” Conclusion: Automated CTP summary maps appear to be relatively accurate in both the detection of acute MCA distribution infarcts, and the discrimination of volumes using a 70 ml threshold.

  15. Extent of metal-silicate disequilibrium during accretion and early differentiation of the Earth

    Science.gov (United States)

    Rubie, D. C.; Nimmo, F.; Morbidelli, A.; Frost, D. J.

    2012-12-01

    Earth, Mars, Venus and Mercury accreted on a timescale of 10-100 My through a series of violent collisions with planetesimals and embryos. The high energy of such impacts was sufficient to cause deep magma ocean formation which facilitated the segregation of metal and silicate liquids. Planetary cores thus formed as a multistage process that was inseparable from the accretion process. In order to better understand the formation and early differentiation of the terrestrial planets, we are integrating a multistage core-formation model with N-body accretion simulations. Constraints on model parameters are the compositions of the Earth's primitive mantle and, to a lesser extent, the mantles of Mars and Mercury which may be FeO rich and FeO-poor respectively. We use a least-squares minimization to optimise 4 model parameters. Elements currently considered include Si, O, Ni, Co, W, Nb, Cr, Ta and V. We concentrate on recent N-body simulations that result in an approximately Earth-mass planet at ~1 AU. In order to satisfy the model constraints, accretion has to be heterogeneous, with embryos and planetesimals originating in the inner part of the solar system (e.g. emulsify and equilibrate in a magma ocean and (2) the fraction of magma oceans that are involved in the equilibration process for both impacting planetesimals and embryos. Both estimates are crucial for interpreting Hf-W age determinations. Best results are obtained when the fraction of silicate mantle/magma ocean that interacts chemically with the metallic cores of impactors is limited and lies in the range 0.003 to 0.1, depending on the size of the impactor and magma ocean depth. The degree of incomplete metal equilibration depends on the extent to which the impactor's mantle participates in the metal-silicate equilibration process.

  16. Synthesis of glycine-containing complexes in impacts of comets on early Earth

    Science.gov (United States)

    Goldman, Nir; Reed, Evan J.; Fried, Laurence E.; William Kuo, I.-F.; Maiti, Amitesh

    2010-11-01

    Delivery of prebiotic compounds to early Earth from an impacting comet is thought to be an unlikely mechanism for the origins of life because of unfavourable chemical conditions on the planet and the high heat from impact. In contrast, we find that impact-induced shock compression of cometary ices followed by expansion to ambient conditions can produce complexes that resemble the amino acid glycine. Our ab initio molecular dynamics simulations show that shock waves drive the synthesis of transient C-N bonded oligomers at extreme pressures and temperatures. On post impact quenching to lower pressures, the oligomers break apart to form a metastable glycine-containing complex. We show that impact from cometary ice could possibly yield amino acids by a synthetic route independent of the pre-existing atmospheric conditions and materials on the planet.

  17. Os isotopes in SNC meteorites and their implications to the early evolution of Mars and Earth

    Science.gov (United States)

    Jagoutz, E.; Luck, J. M.; Othman, D. Ben; Wanke, H.

    1993-01-01

    A new development on the measurement of the Os isotopic composition by mass spectrometry using negative ions opened a new field of applications. The Re-Os systematic provides time information on the differentiation of the nobel metals. The nobel metals are strongly partitioned into metal and sulphide phases, but also the generation of silicate melts might fractionate the Re-Os system. Compared to the other isotopic systems which are mainly dating the fractionation of the alkalis and alkali-earth elements, the Re-Os system is expected to disclose entirely new information about the geochemistry. Especially the differentiation and early evolution of the planets such as the formation of the core will be elucidated with this method.

  18. The Solubility of Rock in Steam Atmospheres of the Early Earth and Hot Rocky Exoplanets

    Science.gov (United States)

    Fegley, Bruce

    2016-07-01

    Extensive experimental studies show all major rock-forming elements (e.g., Si, Mg, Fe, Ca, Al, Na, K) dissolve in steam to a greater or lesser extent. We use these results to compute chemical equilibrium abundances of rocky element - bearing gases in steam atmospheres equilibrated with silicate magma oceans. Rocky elements partition into steam atmospheres as volatile hydroxide gases (e.g., Si(OH)4, Mg(OH)2, Fe(OH)2, Ni(OH)2, Al(OH)3, Ca(OH)2, NaOH, KOH) and via reaction with HF and HCl as volatile halide gases (e.g., NaCl, KCl, CaFOH, CaClOH, FAl(OH)2) in much larger amounts than expected from their vapor pressures over volatile-free solid or molten rock at high temperatures expected for steam atmospheres on the early Earth and hot rocky exoplanets. We quantitatively compute the extent of fractional vaporization by defining gas/magma distribution coefficients and show Earth's sub-solar Si/Mg ratio may be due to loss of a primordial steam atmosphere. We conclude hot rocky exoplanets that are undergoing or have undergone escape of steam-bearing atmospheres may experience fractional vaporization and loss of Si, Mg, Fe, Ni, Al, Ca, Na, and K. This loss can modify their bulk composition, density, heat balance, and interior structure. This work was supported by NSF Astronomy Program Grant AST-1412175.

  19. Differentiation of crusts and cores of the terrestrial planets - Lessons for the early earth

    Science.gov (United States)

    Solomon, S. C.

    1980-01-01

    The extent and mechanisms of global differentiation and the early thermal and tectonic histories of the terrestrial planets are surveyed in order to provide constraints on the first billion years of earth history. Indirect and direct seismic evidence for crusts on the moon, Mars and Venus is presented, and it is pointed out that substantial portions of these crusts have been in place since the cessation of heavy bombardment of the inner solar system four billion years ago. Evidence for sizable cores on Mars and Mercury and a small core on the moon is also discussed, and the heat involved in core formation is pointed out. Examination of the volcanic and tectonic histories of planets lacking plate tectonics indicates that core formation was not closely linked to crust formation on the moon or Mars, with chemical differentiation restricted to shallow regions, and was much more extensive on Mercury. Extension of these considerations to the earth results in a model of a hot and vigorously convecting mantle with an easily deformable crust immediately following core formation, and the gradual development of a lithosphere and plates.

  20. On effect of precession-induced flows in the liquid core for early Earth's history

    Directory of Open Access Journals (Sweden)

    S. L. Shalimov

    2006-01-01

    Full Text Available Secondary and tertiary flow patterns seen in experiments simulating flow in the Earth's liquid core induced by luni-solar precession of the solid mantle (Vanyo et al., 1995 hint at the development of non-axisymmetric columnar periodic structures. A simple interpretation of the structure formation is presented in a hydrodynamic approach. It is suggested that if similar flow patterns can occur in the Earth's liquid core enclosed into precessing and rotating mantle then kinematic of the flows may be regarded as a possible geodynamo mechanism for early Earth's history (before the solid core formation.

  1. The survival of early Earth mantle reservoirs: Evidence from flood basalts

    Science.gov (United States)

    Jackson, M. G.

    2011-12-01

    Over geologic time, large quantities of oceanic crust and sediment have been injected into the mantle at subduction zones, thereby generating heterogeneities in the mantle. The mantle has been further modified by melt extraction at mid-ocean ridges, a process that has generated large depleted reservoirs throughout the mantle. Owing to the fact that the Earth's mantle mixes and stirs chaotically on geologic timescales, it has long been thought that any evidence of an early terrestrial primitive mantle reservoir has either been erased by melt extraction, or has been overprinted by mixing with recycled materials. This hypothesis was supported by a lack of evidence for chondritic primitive mantle material in the mantle sources of oceanic hotspots, which are thought to yield material from the Earth's deep mantle. Instead, ocean island basalts (OIB) exhibit median 143Nd/144Nd isotopic ratios near 0.5130, suggesting that plume fed hotspots sample a largely-depleted mantle. However, the discovery of Boyet and Carlson (2005, Science) presented evidence that the Earth's primitive mantle may not be chondritic in composition. Boyet and Carlson (2005) found that modern terrestrial lavas have 142Nd/144Nd ratios ~18 ppm higher than chondrites. This result implies that all modern crustal and mantle reservoirs derive from a reservoir with Sm/Nd ratios ~5% higher than chondritic. Today, the 143Nd/144Nd of the primitive (albeit non-chondritic) reservoir would be ~0.5130. Critically, this value is similar to the median 143Nd/144Nd ratio identified in OIB lavas, suggesting that the OIB mantle may in fact be a largely primitive reservoir. However, most OIB lavas fail to exhibit the elevated 3He/4He ratios associated with primitive mantle reservoirs. Similarly, OIB lavas generally lack primitive Pb-isotopic compositions that plot on the geochron, a requirement for all early-Earth reservoirs. To date, no terrestrial OIB lavas have been found that exhibit the required He, Nd and Pb

  2. Earth Observations for Early Detection of Agricultural Drought: Contributions of the Famine Early Warning Systems Network (FEWS NET)

    Science.gov (United States)

    Budde, M. E.; Funk, C.; Husak, G. J.; Peterson, P.; Rowland, J.; Senay, G. B.; Verdin, J. P.

    2016-12-01

    The U.S. Geological Survey (USGS) has a long history of supporting the use of Earth observation data for food security monitoring through its role as an implementing partner of the Famine Early Warning Systems Network (FEWS NET) program. The use of remote sensing and crop modeling to address food security threats in the form of drought, floods, pests, and changing climatic regimes has been a core activity in monitoring FEWS NET countries. In recent years, it has become a requirement that FEWS NET apply monitoring and modeling frameworks at global scales to assess emerging crises in regions that FEWS NET does not traditionally monitor. USGS FEWS NET, in collaboration with the University of California, Santa Barbara, has developed a number of new global applications of satellite observations, derived products, and efficient tools for visualization and analyses to address these requirements. (1) A 35-year quasi-global (+/- 50 degrees latitude) time series of gridded rainfall estimates, the Climate Hazards Infrared Precipitation with Stations (CHIRPS) dataset, based on infrared satellite imagery and station observations. Data are available as 5-day (pentadal) accumulations at 0.05 degree spatial resolution. (2) Global actual evapotranspiration data based on application of the Simplified Surface Energy Balance (SSEB) model using 10-day MODIS Land Surface Temperature composites at 1-km resolution. (3) Production of global expedited MODIS (eMODIS) 10-day NDVI composites updated every 5 days. (4) Development of an updated Early Warning eXplorer (EWX) tool for data visualization, analysis, and sharing. (5) Creation of stand-alone tools for enhancement of gridded rainfall data and trend analyses. (6) Establishment of an agro-climatology analysis tool and knowledge base for more than 90 countries of interest to FEWS NET. In addition to these new products and tools, FEWS NET has partnered with the GEOGLAM community to develop a Crop Monitor for Early Warning (CM4EW) which

  3. A model for the evolution of the Earth's mantle structure since the Early Paleozoic

    Science.gov (United States)

    Zhang, Nan; Zhong, Shijie; Leng, Wei; Li, Zheng-Xiang

    2010-06-01

    Seismic tomography studies indicate that the Earth's mantle structure is characterized by African and Pacific seismically slow velocity anomalies (i.e., superplumes) and circum-Pacific seismically fast anomalies (i.e., a globally spherical harmonic degree 2 structure). However, the cause for and time evolution of the African and Pacific superplumes and the degree 2 mantle structure remain poorly understood with two competing proposals. First, the African and Pacific superplumes have remained largely unchanged for at least the last 300 Myr and possibly much longer. Second, the African superplume is formed sometime after the formation of Pangea (i.e., at 330 Ma) and the mantle in the African hemisphere is predominated by cold downwelling structures before and during the assembly of Pangea, while the Pacific superplume has been stable for the Pangea supercontinent cycle (i.e., globally a degree 1 structure before the Pangea formation). Here, we construct a proxy model of plate motions for the African hemisphere for the last 450 Myr since the Early Paleozoic using the paleogeographic reconstruction of continents constrained by paleomagnetic and geological observations. Coupled with assumed oceanic plate motions for the Pacific hemisphere, this proxy model for the plate motion history is used as time-dependent surface boundary condition in three-dimensional spherical models of thermochemical mantle convection to study the evolution of mantle structure, particularly the African mantle structure, since the Early Paleozoic. Our model calculations reproduce well the present-day mantle structure including the African and Pacific superplumes and generally support the second proposal with a dynamic cause for the superplume structure. Our results suggest that while the mantle in the African hemisphere before the assembly of Pangea is predominated by the cold downwelling structure resulting from plate convergence between Gondwana and Laurussia, it is unlikely that the bulk of

  4. Sulfur Isotopic Fractionation During Vacuum Ultraviolet Photolysis of SO2: Implication for Meteorites and Early Earth

    Science.gov (United States)

    Chakraborty, S.; Jackson, T. L.; Rude, B.; Ahmed, M.; Thiemens, M. H.

    2016-12-01

    Several sulfur bearing gas phase species existed in the solar nebula, including H2S, SO2, SiS, OCS, CS2, CS, NS and SO as a consequence of multiple available chemical valence states (S2- to S6+). Sulfur directly condensed into refractory phases in the solar nebula under reducing conditions. Mass independent (MI) sulfur isotopic compositions have been measured in chondrules and organics from chondritic meteorites. Large 33S excesses in sulfides from achondrite meteoritic groups have also been found suggesting that refractory sulfide minerals condensed from a nebular gas with an enhanced carbon to oxygen ratio. Photochemical reactions in the early solar nebula have been inferred to be a leading process in generating MI sulfur compositions. Previously, we have reported wavelength dependent mass-independent sulfur isotopic compositions (with a varying degree in D33S and D36S) in the product elemental sulfur during vacuum ultraviolet (VUV) photodissociation of H2S. Recently we performed photodissociation of SO2 experiments in the wavelength region 98 to 200 nm at low pressures (0.5 torr) using the VUV photons from the Advanced Light Source Synchrotron in a differentially pumped reaction chamber. To our knowledge, this is the first ever experiment to determine the isotopic fractionation in VUV photodissociation of SO2. At VUV energy region, SO2 is mostly predissociative. The measured sulfur isotopic compositions in the product elemental sulfur are MI and dependent on the wavelength. These new results support the previous finding from photodissociation of other di- and tri-atomic molecules (CO, N2, H2S) that predissociative photodissociation produces MI isotopic products and is a quantum mechanically driven selective phenomenon. These new results are useful because (i) they are important in interpreting meteoritic data and decipher sulfur chemistry in the early nebula which is indicative of the redox condition of the nebula (ii) SO2 photolysis in the atmosphere of early

  5. The Indian Health Service Early Childhood Caries Collaborative: A Five-year Summary.

    Science.gov (United States)

    Ricks, Timothy L; Phipps, Kathy R; Bruerd, Bonnie

    2015-01-01

    The purpose of this study was to assess a national initiative's effect on prevalence of early childhood caries and untreated decay in zero- to five-year-old Indian/Alaska Native preschool children. The Indian Health Service (IHS) conducted a five-year Early Childhood Caries Collaborative from October 1, 2009 to September 30, 2014. The program used educational materials and routine communication with the 322 IHS and United States tribal dental programs, with an emphasis on early access to care, dental sealanth, fluoride varnish, and interim therapeutic restorations (ITRs). Prevalence and untreated decay data were obtained through the nationwide oral health survey (2010 and 2014). Data were also collected on access to care, sealants, fluoride, and ITRs. The number of zero- to five-year-olds with a dental visit increased seven percent: dental sealants placed increased 65 percent; and fluoride varnish applications increased 161.2 percent. Between 2010 and 2014, the percentage of one- to two-year-olds with decay experience and untreated decay declined, but the difference was not statistically significant. Early childhood caries prevention strategies, such as early access to dental care, sealants, fluoride varnish, and interim therapeutic restorations, demonstrated some initial improvement in the oral health status of zero- to five-year-old Indian/Alaska Native children.

  6. Evaluation of Parent Involvement in Early Childhood Programs 1979-1980. Technical Summary, Report No. 8130.

    Science.gov (United States)

    McKinney, John

    Evaluation of parent involvement in the following ten early childhood programs in the Philadelphia school district is presented: (1) Child Care (CC); (2) Head Start (HS); (3) Parent Nursery (PN); (4) Get Set (GS); (5) Durham Child Development Center (DCD); (6) Preschool Child Development Project (PCD); (7) Original Follow Through (OFT); (8) Follow…

  7. Committee Opinion Summary No. 638: First-Trimester Risk Assessment for Early-Onset Preeclampsia.

    Science.gov (United States)

    2015-09-01

    Hypertensive disorders with adverse sequelae (including preterm birth, maternal morbidity and mortality, and long-term risk of maternal cardiovascular disease) complicate 5-10% of pregnancies. Early identification of pregnant women at risk of developing early-onset preeclampsia would theoretically allow referral for more intensive surveillance or application of preventive therapies to reduce the risk of severe disease. In practice, however, the effectiveness of such triage would be hindered by the low positive predictive value for early-onset preeclampsia reported in the literature. In spite of the modest predictive value of first-trimester preeclampsia risk assessment and the lack of data demonstrating improved clinical outcomes, commercial tests are being marketed for the prediction of preeclampsia in the first trimester. Taking a detailed medical history to evaluate for risk factors is currently the best and only recommended screening approach for preeclampsia; it should remain the method of screening for preeclampsia until studies show that aspirin or other interventions reduce the incidence of preeclampsia for women at high risk based on first-trimester predictive tests.

  8. Cracking the Code of Soil Genesis. The Early Role of Rare Earth Elements

    Science.gov (United States)

    Zaharescu, D. G.; Dontsova, K.; Burghelea, C. I.; Maier, R. M.; Huxman, T. E.; Chorover, J.

    2014-12-01

    Soil is terrestrial life support system. Its genesis involves tight interactions between biota and mineral surfaces that mobilize structural elements into biogeochemical cycles. Of all chemical elements rare earth elements (REE) are a group of 16 non-nutrient elements of unusual geochemical similarity and present in all components of the surface environment. While much is known about the role of major nutrients in soil development we lack vital understanding of how early biotic colonization affects more conservative elements such as REE. A highly controlled experiment was set up at University of Arizona's Biosphere-2 that tested the effect of 4 biological treatments, incorporating a combination of microbe, grass, mycorrhiza and uninoculated control on REE leaching and uptake in 4 bedrock substrates: basalt, rhyolite, granite and schist. Generally the response of REE to biota presence was synergistic. Variation in total bedrock chemistry could explain major trends in pore water REE. There was a fast transition from chemistry-dominated to a biota dominated environment in the first 3-4 months of inoculation/seeding which translated into increase in REE signal over time. Relative REE abundances in water were generally reflected in plant concentrations, particularly in root, implying that below ground biomass is the main sync of REE in the ecosystem. Mycorrhiza effect on REE uptake in plant organs was significant and increased with infection rates. Presence of different biota translated into subtle differences in REE release, reveling potential biosignatures of biolota-rock colonization. The results thus bring fundamental insight into early stages non-nutrient cycle and soil genesis.

  9. Geologic constraints on earth system sensitivity to CO2 during the Cretaceous and early Paleogene

    Directory of Open Access Journals (Sweden)

    D. J. Beerling

    2011-03-01

    Full Text Available Earth system sensitivity (ESS is the long-term (>103 yr equilibrium temperature response to doubled CO2. ESS has climate policy implications because global temperatures are not expected to decline appreciably for at least 103 yr, even if anthropogenic greenhouse-gas emissions drop to zero. We report quantitative ESS estimates of 3 °C or higher for much of the Cretaceous and early Paleogene based on paleo-reconstructions of CO2 and temperature. These estimates are generally higher than climate sensitivities simulated from global climate models for the same ancient periods (~3 °C. We conclude that climate models do not capture the full suite of positive climate feedbacks during greenhouse worlds. These absent feedbacks are probably related to clouds, trace greenhouse gases, seasonal snow cover, and/or vegetation, especially in polar regions. Continued warming in the coming decades as anthropogenic greenhouse gases accumulate in the atmosphere ensures that characterizing and quantifying these positive climate feedbacks will become a scientific challenge of increasing priority.

  10. Meteorite Impact-Induced Rapid NH3 Production on Early Earth: Ab Initio Molecular Dynamics Simulation

    Science.gov (United States)

    Shimamura, Kohei; Shimojo, Fuyuki; Nakano, Aiichiro; Tanaka, Shigenori

    2016-12-01

    NH3 is an essential molecule as a nitrogen source for prebiotic amino acid syntheses such as the Strecker reaction. Previous shock experiments demonstrated that meteorite impacts on ancient oceans would have provided a considerable amount of NH3 from atmospheric N2 and oceanic H2O through reduction by meteoritic iron. However, specific production mechanisms remain unclear, and impact velocities employed in the experiments were substantially lower than typical impact velocities of meteorites on the early Earth. Here, to investigate the issues from the atomistic viewpoint, we performed multi-scale shock technique-based ab initio molecular dynamics simulations. The results revealed a rapid production of NH3 within several picoseconds after the shock, indicating that shocks with greater impact velocities would provide further increase in the yield of NH3. Meanwhile, the picosecond-order production makes one expect that the important nitrogen source precursors of amino acids were obtained immediately after the impact. It was also observed that the reduction of N2 proceeded according to an associative mechanism, rather than a dissociative mechanism as in the Haber-Bosch process.

  11. [World"--an unlikely scenario of the life origin and early ecolution on Earth].

    Science.gov (United States)

    Bregestowski, P D

    2015-01-01

    The most widely accepted modern scenario of prebiotic evolution that led to the emergence of the first cells on our planet is the "RNA World"--a hypothetical period of the early Earth's biosphere, when the information transfer and all the processes necessary for the functioning of the primary systems were provided by replicating RNA molecules. The essence of the "RNA World" hypothesis is based on two postulates: 1) at the initial stages of the origin of life, RNA molecules performed all functions necessary for reproduction and replication of biological molecules: informational, catalytic and structural; 2) at a certain stage of evolution arose separation of RNA and DNA, appeared genetically encoded proteins and occurred a transition to the modern world of living systems functioning. However, the analysis shows that the hypothesis of "RNA World" has a number of unsurmountable problems of chemical and informational nature. The biggest of them are: a) the unreliability of the initial components synthesis; b) a catastrophic rise of polynucleotide chains instability with their elongation; c) catastrophically low probability of formation of sequences possessing meaningful information; d) lack of a mechanism determining the regularities division of the membrane vesicles permeable to nitrogen bases and other RNA components; e) lack of driving forces for the transition from the RNA world to the much more complex world based on DNA and RNA. Therefore, the "RNA World" scenario seems unlikely.

  12. A new model for early differentiation and chemical stratification of the Earth's mantle

    Science.gov (United States)

    Rubie, D. C.; Gessmann, C. K.; Frost, D. J.

    2003-04-01

    New experimental data on the solubility of oxygen in liquid Fe-rich alloy enable the geochemical consequences of core formation and the early geochemical evolution of the Earth's mantle to be better constrained. We have studied oxygen solubility in liquid Fe-alloy at 5-23 GPa, 2100--2700 K and variable oxygen fugacities using a multianvil apparatus. At constant oxygen fugacity, O solubility increases with increasing temperature but decreases with increasing pressure. Thus, along a high temperature adiabat (e.g. after formation of a deep magma ocean), oxygen solubility is high at relatively shallow depths (e.g. 3000 K) in a magma ocean result in significant Si being dissolved in liquid Fe-alloy whereas at depths >800--1000 km the solubility starts to decrease again and becomes close to zero at the CMB (Gessmann et al. 2001, EPSL 184, 367). Thus migration of liquid metal during core formation provides a mechanism for enriching the lower part of the mantle in the FeO component, and possibly also in SiO_2, relative to the upper part.

  13. Tidal dissipation in the lunar magma ocean and its effect on the early evolution of the Earth-Moon system

    Science.gov (United States)

    Chen, Erinna M. A.; Nimmo, Francis

    2016-09-01

    The present-day inclination of the Moon reflects the entire history of its thermal and orbital evolution. The Moon likely possessed a global magma ocean following the Moon-forming impact. In this work, we develop a coupled thermal-orbital evolution model that takes into account obliquity tidal heating in the lunar magma ocean. Dissipation in the magma ocean is so effective that it results in rapid inclination damping at semi-major axes beyond about 20 Earth radii (RE), because of the increase in lunar obliquity as the so-called Cassini state transition at ≈30 RE is approached. There is thus a "speed limit" on how fast the Moon can evolve outwards while maintaining its inclination: if it reaches 20 RE before the magma ocean solidifies, any early lunar inclination cannot be maintained. We find that for magma ocean lifetimes of 10 Myr or more, the Earth's tidal quality factor Q must have been >300 to maintain primordial inclination, implying an early Earth 1-2 orders of magnitude less dissipative than at present. On the other hand, if tidal dissipation on the early Earth was stronger, our model implies rapid damping of the lunar inclination and requires subsequent late excitation of the lunar orbit after the crystallization of the lunar magma ocean.

  14. The principal rare earth elements deposits of the United States-A summary of domestic deposits and a global perspective

    Science.gov (United States)

    Long, Keith R.; Van Gosen, Bradley S.; Foley, Nora K.; Cordier, Daniel

    2010-01-01

    The rare earth elements (REE) are fifteen elements with atomic numbers 57 through 71, from lanthanum to lutetium ('lanthanides'), plus yttrium (39), which is chemically similar to the lanthanide elements and thus typically included with the rare earth elements. Although industrial demand for these elements is relatively small in tonnage terms, they are essential for a diverse and expanding array of high-technology applications. REE-containing magnets, metal alloys for batteries and light-weight structures, and phosphors are essential for many current and emerging alternative energy technologies, such as electric vehicles, energy-efficient lighting, and wind power. REE are also critical for a number of key defense systems and other advanced materials. Section 843 of the National Defense Authorization Act for Fiscal Year 2010, Public Law 111-84, directs the Comptroller General to complete a report on REE materials in the defense supply chain. The Office of Industrial Policy, in collaboration with other U.S. Government agencies, has initiated (in addition to this report) a detailed study of REE. This latter study will assess the Department of Defense's use of REE, as well as the status and security of domestic and global supply chains. That study will also address vulnerabilities in the supply chain and recommend ways to mitigate any potential risks of supply disruption. To help conduct this study, the Office of Industrial Policy asked the U.S. Geological Survey (USGS) to report on domestic REE reserves and resources in a global context. To this end, the enclosed report is the initial USGS contribution to assessing and summarizing the domestic REE resources in a global perspective. In 2009, the Mineral Resources Program of the USGS organized a new project under the title Minerals at Risk and For Emerging Technologies in order to evaluate mineral resource and supply issues of rare metals that are of increasing importance to the national economy. Leaders and members of

  15. Summary and evaluation of the parametric study of potential early commercial MHD power plants (PSPEC)

    Energy Technology Data Exchange (ETDEWEB)

    Staiger, P.J.; Abbott, J.M.

    1980-06-01

    The Parametric Study of Potential Early Commercial MHD Power Plants is described and the results of the study are summarized. Two parallel contracted studies were conducted. Each contractor investigated three base cases and parametric variation about these base cases. Each contractor concluded that two of the base cases (a plant using separate firing of an advanced high temperature regenerative air heater with fuel from an advanced coal gasifier and a plant using an intermediate temperature metallic recuperative heat exchanger to heat oxygen enriched combustion air) were comparable in both performance and cost of electricity. The contractors differed in the level of their cost estimates with the capital cost estimates for the MHD topping cycle and the magnet subsystem in particular accounting for a significant part of the difference. The impact of the study on the decision to pursue a course which leads to an oxygen enriched plant as the first commercial MHD plant is described.

  16. Early evolution and dynamics of Earth from a molten initial stage

    Science.gov (United States)

    Louro Lourenço, Diogo; Tackley, Paul J.

    2016-04-01

    It is now well established that most of the terrestrial planets underwent a magma ocean stage during their accretion. On Earth, it is probable that at the end of accretion, giant impacts like the hypothesised Moon-forming impact, together with other sources of heat, melted a substantial part of the mantle. The thermal and chemical evolution of the resulting magma ocean most certainly had dramatic consequences on the history of the planet. Considerable research has been done on magma oceans using simple 1-D models (e.g.: Abe, PEPI 1997; Solomatov, Treat. Geophys. 2007; Elkins-Tanton EPSL 2008). However, some aspects of the dynamics may not be adequately addressed in 1-D and require the use of 2-D or 3-D models. Moreover, new developments in mineral physics that indicate that melt can be denser than solid at high pressures (e.g.: de Koker et al., EPSL 2013) can have very important impacts on the classical views of the solidification of magma oceans (Labrosse et al., Nature 2007). The goal of our study is to understand and characterize the influence of melting on the long-term thermo-chemical evolution of rocky planet interiors, starting from an initial molten state (magma ocean). Our approach is to model viscous creep of the solid mantle, while parameterizing processes that involve melt as previously done in 1-D models, including melt-solid separation at all melt fractions, the use of an effective diffusivity to parameterize turbulent mixing, coupling to a parameterized core heat balance and a radiative surface boundary condition. These enhancements have been made to the numerical code StagYY (Tackley, PEPI 2008). We present results for the evolution of an Earth-like planet from a molten initial state to present day, while testing the effect of uncertainties in parameters such as melt-solid density differences, surface heat loss and efficiency of turbulent mixing. Our results show rapid cooling and crystallization until the rheological transition then much slower

  17. What is the Emerging Knowledge of the Early Earth from the Oldest (>3.6 Ga) Rocks?

    Science.gov (United States)

    Bennett, V. C.; Nutman, A. P.

    2016-12-01

    Eoarchean to Hadean rocks are direct samples of early Earth chemistry and conditions and provide the ground-truth for models of early Earth formation, environments and evolution. Intensive investigations by many groups reveal rocks of this age comprise only one millionth of Earth's surface and are found in 9 areas of varying extent distributed worldwide. This record is of variable fidelity however, owing to metamorphic overprinting. The majority of the oldest rocks are high grade gneisses with protoliths from mid-crustal levels; the more rare supracrustal assemblages reflect early Earth's surface conditions and processes. First-order observations from supracrustal sequences at several localities and from 3.6 Ga to ≥3.9 Ga in age provide abundant evidence of liquid water at the Earth's surface with pillow basalts and chemical sedimentary rocks in the form of cherts, banded Fe formations and carbonates. Trace element patterns of these sedimentary rocks strongly resemble modern seawater compositions, except for the absence of redox sensitive Ce anomalies. Evidence for early life remains controversial and is mainly in the form of stable isotopic signatures of C and Fe. Our recent work from newly-discovered, exceptionally well-preserved 3.7 Ga sedimentary rocks and the deformed unconformity they rest on has provided the first evidence of Eoarchean intense weathering and shallow water sedimentary processes. Whilst the major and trace element compositions of Eoarchean gneisses have analogs in younger rocks in accord with a continuum of crust formation processes, radiogenic isotopic signatures from both long and short half-life decay schemes record an image of the Earth in transition from early differentiation processes, likely associated with planetary accretion and formation, to more modern styles. Most Eoarchean rocks possess extinct nuclide anomalies in the form of 142Nd and 182W isotopic signatures that are absent in modern terrestrial samples, and developed from

  18. Microbes, Mineral Evolution, and the Rise of Microcontinents-Origin and Coevolution of Life with Early Earth.

    Science.gov (United States)

    Grosch, Eugene G; Hazen, Robert M

    2015-10-01

    Earth is the most mineralogically diverse planet in our solar system, the direct consequence of a coevolving geosphere and biosphere. We consider the possibility that a microbial biosphere originated and thrived in the early Hadean-Archean Earth subseafloor environment, with fundamental consequences for the complex evolution and habitability of our planet. In this hypothesis paper, we explore possible venues for the origin of life and the direct consequences of microbially mediated, low-temperature hydrothermal alteration of the early oceanic lithosphere. We hypothesize that subsurface fluid-rock-microbe interactions resulted in more efficient hydration of the early oceanic crust, which in turn promoted bulk melting to produce the first evolved fragments of felsic crust. These evolved magmas most likely included sialic or tonalitic sheets, felsic volcaniclastics, and minor rhyolitic intrusions emplaced in an Iceland-type extensional setting as the earliest microcontinents. With the further development of proto-tectonic processes, these buoyant felsic crustal fragments formed the nucleus of intra-oceanic tonalite-trondhjemite-granitoid (TTG) island arcs. Thus microbes, by facilitating extensive hydrothermal alteration of the earliest oceanic crust through bioalteration, promoted mineral diversification and may have been early architects of surface environments and microcontinents on young Earth. We explore how the possible onset of subseafloor fluid-rock-microbe interactions on early Earth accelerated metavolcanic clay mineral formation, crustal melting, and subsequent metamorphic mineral evolution. We also consider environmental factors supporting this earliest step in geosphere-biosphere coevolution and the implications for habitability and mineral evolution on other rocky planets, such as Mars.

  19. Hf and Nd Isotope Evidence for Production of an Incompatible Trace Element Enriched Crustal Reservoir in Early Earth (Invited)

    Science.gov (United States)

    Brandon, A. D.; Debaille, V.; Lapen, T. J.

    2010-12-01

    The final significant stage of accretion of the Earth was likely a collision between proto-Earth and a Mars sized impactor that formed the Moon. This event is thought to have produced enough thermal energy to melt all or most of the Earth, with a consequent magma ocean (MO). During subsequent cooling, the Earth would have formed its protocrust and corresponding mantle lithosphere, consisting of solidified basalt-komatiitic melt, in combination with buoyant cumulates and late stage residual melts from the MO. Relative to the convecting mantle, portions of this protolithosphere are likely to have been enriched in incompatible trace elements (ITE) in sufficient quantities to contain a significant amount of the bulk Earth’s budget for rare earth elements, U, Th, and Hf. If the protolithosphere was negatively buoyant, it may have overturned at or near the final stages of MO crystallization and a significant portion of that material may have been transported into the deep mantle where it resided and remixed into the convecting mantle over Earth history [1,2]. If the protolithosphere remained positively buoyant, its crust would have likely begun to erode from surface processes, and subsequently recycled back into the mantle over time as sediment and altered crust, once a subduction mechanism arose. The Nd and Hf isotopic compositions of Earth’s earliest rocks support the idea that an early-formed ITE-enriched reservoir was produced. The maxima in 142Nd/144Nd for 3.85 to 3.64 Ga rocks from Isua, Greenland decreases from +20 ppm to +12 ppm relative to the present day mantle value, respectively [3]. This indicates mixing of an early-formed ITE enriched reservoir back into the convecting mantle. In addition, zircons from the 3.1 Ga Jack Hills conglomerate indicate that material with an enriched 176Lu/177Hf of ~0.02 and an age of 4.4 Ga or greater was present at the Earth’s surface over the first 2 Ga of Earth history, supporting the scenario of a positively buoyant

  20. Thermochemical equilibrium calculations of high-temperature O2 generation on the early Earth: Giant asteroid impacts on land

    Directory of Open Access Journals (Sweden)

    PAVLE I. PREMOVIC

    2003-02-01

    Full Text Available Earth’s atmosphere is composed primarily of N2 and O2. The origin of free O2 in the early Earth’s atmosphere is still subject of considerable debate.1 Theoretical models suggest that the initial form of free O2 in the atmosphere has been oceanic H2O. Recent computation modelling has suggested that a superheated (ca. 2000 K H2O vapor atmosphere of 1.4x1021 kg (the present mass of the oceans lasting for about 3000 y could probably have been formed on Earth by an enormous (ca. 1028 J asteroid impact. In this report, the occurrence of the thermochemical dissociation of the vapor, creating a primitive oxygenic (ca. 0.1 of the present level (PAL of free O2 atmosphere.

  1. Biomolecule-Mineral Interactions in the Geochemical Environment on Early Earth and in the Human Body

    Science.gov (United States)

    Sahai, N.

    2011-12-01

    We worked on four projects consistent with the broad goals of the grant to investigate (i) the potential impacts of mineral surface chemistry and particle size on the stability and viability of cell membranes, bacteria and human cells and (ii) the influence of biomolecules on mineral nucleation and growth. The projects are of relevance to the origin and early evolution of life, biomineralization, medical mineralogy, and environmental biogeochemistry. The freedom enabled by the five-year grant to explore high-risk scientific areas, and the resulting high impact outcomes, cannot be overstated. We developed an almost entirely new field of Medical Mineralogyy and extended our concepts and knowledge-base to the potential roles of mineral surfaces in the evolution of protocells and the earliest cells. These exciting connections to medical mineralogy, and to the origin and evolution of life on early Earth are fascinating topics to the general public and even to other scientists, especially when the links to mineralogy and geochemistry are highlighted. In brief, we examined the stability of lipid bilayers representing model protocell membranes comprised of phospholipid bilayers with mineral surfaces. We found that the stability of lipid bilayers depends on mineral surface charge and increases as silica glass ~ quartz human either inadvertently as inhaled dusts or are inserted by design such as in components of orthopedic implants. It is important to know how the mineral surface properties affect the body's immune system response. We found that adhesion/detachment force of the Jurkat -line of T-lymphocytes increased as SiO2 glass ~ quartz < rutile (100) ~ mica (001) < polycrystalline corundum, and was related to the unraveling of cell surface glycoproteins, and to mineral surface charge. The studies described above have resulted in 23 peer-reviewed publications to date (published or in review or in prep.); one MSA volume and one Elements issue edited by the P.I.; trained

  2. Paleomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, G.H.M.A.

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally

  3. Palaeomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, Gerardus Henricus Martina Anna

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally

  4. Palaeomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, Gerardus Henricus Martina Anna

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally accept

  5. Paleomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, G.H.M.A.

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally accept

  6. Palaeomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, Gerardus Henricus Martina Anna

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally accept

  7. Paleomagnetism of late Archaean flood basalt terrains : implications for early Earth geodynamics and geomagnetism

    NARCIS (Netherlands)

    Strik, G.H.M.A.

    2004-01-01

    Palaeomagnetic studies are e.g. important for demonstrating and quantifying horizontal movement and rotation of pieces of the Earth's crust. The constant movement and recycling of plates, in other words plate tectonics, is an important mechanism for the Earth to lose its heat. It is generally accept

  8. A warm or a cold early Earth? New insights from a 3-D climate-carbon model

    Science.gov (United States)

    Charnay, Benjamin; Le Hir, Guillaume; Fluteau, Frédéric; Forget, François; Catling, David C.

    2017-09-01

    Oxygen isotopes in marine cherts have been used to infer hot oceans during the Archean with temperatures between 60 °C (333 K) and 80 °C (353 K). Such climates are challenging for the early Earth warmed by the faint young Sun. The interpretation of the data has therefore been controversial. 1D climate modeling inferred that such hot climates would require very high levels of CO2 (2-6 bars). Previous carbon cycle modeling concluded that such stable hot climates were impossible and that the carbon cycle should lead to cold climates during the Hadean and the Archean. Here, we revisit the climate and carbon cycle of the early Earth at 3.8 Ga using a 3D climate-carbon model. We find that CO2 partial pressures of around 1 bar could have produced hot climates given a low land fraction and cloud feedback effects. However, such high CO2 partial pressures should not have been stable because of the weathering of terrestrial and oceanic basalts, producing an efficient stabilizing feedback. Moreover, the weathering of impact ejecta during the Late Heavy Bombardment (LHB) would have strongly reduced the CO2 partial pressure leading to cold climates and potentially snowball Earth events after large impacts. Our results therefore favor cold or temperate climates with global mean temperatures between around 8 °C (281 K) and 30 °C (303 K) and with 0.1-0.36 bar of CO2 for the late Hadean and early Archean. Finally, our model suggests that the carbon cycle was efficient for preserving clement conditions on the early Earth without necessarily requiring any other greenhouse gas or warming process.

  9. Replicating the Ice-Volume Signal of the Early Pleistocene with a Complex Earth System Model

    Science.gov (United States)

    Tabor, C. R.; Poulsen, C. J.; Pollard, D.

    2013-12-01

    Milankovitch theory proposes high-latitude summer insolation intensity paces the ice ages by controlling perennial snow cover amounts (Milankovitch, 1941). According to theory, the ~21 kyr cycle of precession should dominate the ice-volume records since it has the greatest influence on high-latitude summer insolation. Modeling experiments frequently support Milankovitch theory by attributing the majority of Northern Hemisphere high-latitude summer snowmelt to changes in the cycle of precession (e.g. Jackson and Broccoli, 2003). However, ice-volume proxy records, especially those of the Early Pleistocene (2.6-0.8 Ma), display variability with a period of ~41 kyr (Raymo and Lisiecki, 2005), indicative of insolation forcing from obliquity, which has a much smaller influence on summer insolation intensity than precession. Several hypotheses attempt to explain the discrepancies between Milkankovitch theory and the proxy records by invoking phenomena such as insolation gradients (Raymo and Nisancioglu, 2003), hemispheric offset (Raymo et al., 2006; Lee and Poulsen, 2009), and integrated summer energy (Huybers, 2006); however, all of these hypotheses contain caveats (Ruddiman, 2006) and have yet to be supported by modeling studies that use a complex GCM. To explore potential solutions to this '41 kyr problem,' we use an Earth system model composed of the GENESIS GCM and Land Surface model, the BIOME4 vegetation model, and the Pennsylvania State ice-sheet model. Using an asynchronous coupling technique, we run four idealized transient combinations of obliquity and precession, representing the orbital extremes of the Pleistocene (Berger and Loutre, 1991). Each experiment is run through several complete orbital cycles with a dynamic ice domain spanning North America and Greenland, and fixed preindustrial greenhouse-gas concentrations. For all orbital configurations, model results produce greater ice-volume spectral power at the frequency of obliquity despite significantly

  10. Comets as Messengers from the Early Solar System - Emerging Insights on Delivery of Water, Nitriles, and Organics to Earth

    Science.gov (United States)

    Mumma, Michael J.; Charnley, Steven B.

    2012-01-01

    The question of exogenous delivery of water and organics to Earth and other young planets is of critical importance for understanding the origin of Earth's volatiles, and for assessing the possible existence of exo-planets similar to Earth. Viewed from a cosmic perspective, Earth is a dry planet, yet its oceans are enriched in deuterium by a large factor relative to nebular hydrogen and analogous isotopic enrichments in atmospheric nitrogen and noble gases are also seen. Why is this so? What are the implications for Mars? For icy Worlds in our Planetary System? For the existence of Earth-like exoplanets? An exogenous (vs. outgassed) origin for Earth's atmosphere is implied, and intense debate on the relative contributions of comets and asteroids continues - renewed by fresh models for dynamical transport in the protoplanetary disk, by revelations on the nature and diversity of volatile and rocky material within comets, and by the discovery of ocean-like water in a comet from the Kuiper Belt (cf., Mumma & Charnley 2011). Assessing the creation of conditions favorable to the emergence and sustenance of life depends critically on knowledge of the nature of the impacting bodies. Active comets have long been grouped according to their orbital properties, and this has proven useful for identifying the reservoir from which a given comet emerged (OC, KB) (Levison 1996). However, it is now clear that icy bodies were scattered into each reservoir from a range of nebular distances, and the comet populations in today's reservoirs thus share origins that are (in part) common. Comets from the Oort Cloud and Kuiper Disk reservoirs should have diverse composition, resulting from strong gradients in temperature and chemistry in the proto-planetary disk, coupled with dynamical models of early radial transport and mixing with later dispersion of the final cometary nuclei into the long-term storage reservoirs. The inclusion of material from the natal interstellar cloud is probable

  11. A Mercury-like component of early Earth yields uranium in the core and high mantle (142)Nd.

    Science.gov (United States)

    Wohlers, Anke; Wood, Bernard J

    2015-04-16

    Recent (142)Nd isotope data indicate that the silicate Earth (its crust plus the mantle) has a samarium to neodymium elemental ratio (Sm/Nd) that is greater than that of the supposed chondritic building blocks of the planet. This elevated Sm/Nd has been ascribed either to a 'hidden' reservoir in the Earth or to loss of an early-formed terrestrial crust by impact ablation. Since removal of crust by ablation would also remove the heat-producing elements--potassium, uranium and thorium--such removal would make it extremely difficult to balance terrestrial heat production with the observed heat flow. In the 'hidden' reservoir alternative, a complementary low-Sm/Nd layer is usually considered to reside unobserved in the silicate lower mantle. We have previously shown, however, that the core is a likely reservoir for some lithophile elements such as niobium. We therefore address the question of whether core formation could have fractionated Nd from Sm and also acted as a sink for heat-producing elements. We show here that addition of a reduced Mercury-like body (or, alternatively, an enstatite-chondrite-like body) rich in sulfur to the early Earth would generate a superchondritic Sm/Nd in the mantle and an (142)Nd/(144)Nd anomaly of approximately +14 parts per million relative to chondrite. In addition, the sulfur-rich core would partition uranium strongly and thorium slightly, supplying a substantial part of the 'missing' heat source for the geodynamo.

  12. False Negatives for Remote Life Detection on Ocean-Bearing Planets: Lessons from the Early Earth.

    Science.gov (United States)

    Reinhard, Christopher T; Olson, Stephanie L; Schwieterman, Edward W; Lyons, Timothy W

    2017-04-01

    Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes throughout its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has centered on refining our understanding of false positives for remote life detection, much less attention has been paid to the possibility of false negatives, that is, cryptic biospheres that are widespread and active on a planet's surface but are ultimately undetectable or difficult to detect in the composition of a planet's atmosphere. Here, we summarize recent developments from geochemical proxy records and Earth system models that provide insight into the long-term evolution of the most readily detectable potential biosignature gases on Earth-oxygen (O2), ozone (O3), and methane (CH4). We suggest that the canonical O2-CH4 disequilibrium biosignature would perhaps have been challenging to detect remotely during Earth's ∼4.5-billion-year history and that in general atmospheric O2/O3 levels have been a poor proxy for the presence of Earth's biosphere for all but the last ∼500 million years. We further suggest that detecting atmospheric CH4 would have been problematic for most of the last ∼2.5 billion years of Earth's history. More broadly, we stress that internal oceanic recycling of biosignature gases will often render surface biospheres on ocean-bearing silicate worlds cryptic, with the implication that the planets most conducive to the development and maintenance of a pervasive biosphere will often be challenging to characterize via conventional atmospheric biosignatures. Key Words: Biosignatures-Oxygen-Methane-Ozone-Exoplanets-Planetary habitability. Astrobiology 17, 287-297.

  13. Early non-destructive biofouling detection in spiral wound RO Membranes using a mobile earth's field NMR

    KAUST Repository

    Fridjonsson, E.O.

    2015-04-20

    We demonstrate the use of Earth\\'s field (EF) Nuclear Magnetic Resonance (NMR) to provide early non-destructive detection of active biofouling of a commercial spiral wound reverse osmosis (RO) membrane module. The RO membrane module was actively biofouled to different extents, by the addition of biodegradable nutrients to the feed stream, as revealed by a subtle feed-channel pressure drop increase. Easily accessible EF NMR parameters (signal relaxation parameters T1, T2 and the total NMR signal modified to be sensitive to stagnant fluid only) were measured and analysed in terms of their ability to detect the onset of biofouling. The EF NMR showed that fouling near the membrane module entrance significantly distorted the flow field through the whole membrane module. The total NMR signal is shown to be suitable for non-destructive early biofouling detection of spiral wound membrane modules, it was readily deployed at high (operational) flow rates, was particularly sensitive to flow field changes due to biofouling and could be deployed at any position along the membrane module axis. In addition to providing early fouling detection, the mobile EF NMR apparatus could also be used to (i) evaluate the production process of spiral wound membrane modules, and (ii) provide an in-situ determination of module cleaning process efficiency.

  14. Early Stage of Origin of Earth (interval after Emergence of Sun, Formation of Liquid Core, Formation of Solid Core)

    Science.gov (United States)

    Pechernikova, G. V.; Sergeev, V. N.

    2017-05-01

    Gravitational collapse of interstellar molecular cloud fragment has led to the formation of the Sun and its surrounding protoplanetary disk, consisting of 5 × 10^5 dust and gas. The collapse continued (1 years. Age of solar system (about 4.57×10^9 years) determine by age calcium-aluminum inclusions (CAI) which are present at samples of some meteorites (chondrites). Subsidence of dust to the central plane of a protoplanetary disk has led to formation of a dust subdisk which as a result of gravitational instability has broken up to condensations. In the process of collisional evolution they turned into dense planetesimals from which the planets formed. The accounting of a role of large bodies in evolution of a protoplanetary swarm in the field of terrestrial planets has allowed to define times of formation of the massive bodies permitting their early differentiation at the expense of short-lived isotopes heating and impacts to the melting temperature of the depths. The total time of Earth's growth is estimated about 10^8 years. Hf geochronometer showed that the core of the Earth has existed for Using W about 3×10^7 Hf geohronometer years since the formation of the CAI. Thus data W point to the formation of the Earth's core during its accretion. The paleomagnetic data indicate the existence of Earth's magnetic field past 3.5×10^9 years. But the age of the solid core, estimated by heat flow at the core-mantle boundary is 1.7×10^9 (0.5 years). Measurements of the thermal conductivity of liquid iron under the conditions that exist in the Earth's core, indicate the absence of the need for a solid core of existence to support the work geodynamo, although electrical resistivity measurements yield the opposite result.

  15. Minds on Earth Hour--A Theme for Sustainability in Swedish Early Childhood Education

    Science.gov (United States)

    Ärlemalm-Hagsér, Eva

    2013-01-01

    This educational science article illustrates education for sustainability in a theme about Earth Hour (energy conservation) in one Swedish preschool. This case study is based on audio recordings of dialogues between children aged five to six years and preschool teachers. It is guided by critical theory, which is also used as a conceptual tool to…

  16. Early Mission Maneuver Operations for the Deep Space Climate Observatory Sun-Earth L1 Libration Point Mission

    Science.gov (United States)

    Roberts, Craig; Case, Sara; Reagoso, John; Webster, Cassandra

    2015-01-01

    The Deep Space Climate Observatory mission launched on February 11, 2015, and inserted onto a transfer trajectory toward a Lissajous orbit around the Sun-Earth L1 libration point. This paper presents an overview of the baseline transfer orbit and early mission maneuver operations leading up to the start of nominal science orbit operations. In particular, the analysis and performance of the spacecraft insertion, mid-course correction maneuvers, and the deep-space Lissajous orbit insertion maneuvers are discussed, com-paring the baseline orbit with actual mission results and highlighting mission and operations constraints..

  17. Hybrid Differential Evolution Optimisation for Earth Observation Satellite Scheduling with Time-Dependent Earliness-Tardiness Penalties

    Directory of Open Access Journals (Sweden)

    Guoliang Li

    2017-01-01

    Full Text Available We study the order acceptance and scheduling (OAS problem with time-dependent earliness-tardiness penalties in a single agile earth observation satellite environment where orders are defined by their release dates, available processing time windows ranging from earliest start date to deadline, processing times, due dates, sequence-dependent setup times, and revenues. The objective is to maximise total revenue, where the revenue from an order is a piecewise linear function of its earliness and tardiness with reference to its due date. We formulate this problem as a mixed integer linear programming model and develop a novel hybrid differential evolution (DE algorithm under self-adaptation framework to solve this problem. Compared with classical DE, hybrid DE employs two mutation operations, scaling factor adaptation and crossover probability adaptation. Computational tests indicate that the proposed algorithm outperforms classical DE in addition to two other variants of DE.

  18. Deep Phylogeny—How a Tree Can Help Characterize Early Life on Earth

    OpenAIRE

    Gaucher, Eric A.; Kratzer, James T.; Randall, Ryan N.

    2010-01-01

    The Darwinian concept of biological evolution assumes that life on Earth shares a common ancestor. The diversification of this common ancestor through speciation events and vertical transmission of genetic material implies that the classification of life can be illustrated in a tree-like manner, commonly referred to as the Tree of Life. This article describes features of the Tree of Life, such as how the tree has been both pruned and become bushier throughout the past century as our knowledge...

  19. The split fate of the early Earth, Mars, Venus, and Moon

    Science.gov (United States)

    Albarède, Francis; Blichert-Toft, Janne

    2007-11-01

    Plate tectonics shaped the Earth, whereas the Moon is a dry and inactive desert, Mars probably came to rest within the first billion years of its history, and Venus, although internally very active, has a dry inferno for its surface. Here we review the parameters that determined the fates of each of these planets and their geochemical expressions. The strong gravity field of a large planet allows for an enormous amount of gravitational energy to be released, causing the outer part of the planetary body to melt (magma ocean), helps retain water on the planet, and increases the pressure gradient. The weak gravity field and anhydrous conditions prevailing on the Moon stabilized, on top of its magma ocean, a thick buoyant plagioclase lithosphere, which insulated the molten interior. On Earth, the buoyant hydrous phases (serpentines) produced by reactions between the terrestrial magma ocean and the wet impactors received from the outer solar system isolated the magma and kept it molten for some few tens of million years. The planets from the inner solar system accreted dry: foundering of wet surface material softened the terrestrial mantle and set the scene for the onset of plate tectonics. This very same process also may have removed all the water from the surface of Venus and added enough water to its mantle to make its internal dynamics very strong and keep the surface very young. Because of a radius smaller than that of the Earth, not enough water could be drawn into the Martian mantle before it was lost to space and Martian plate tectonics never began. The radius of a planet is therefore the key parameter controlling most of its evolutional features.

  20. The earth radiation budget satellite system of the early 1980's

    Science.gov (United States)

    Cooper, J. E.; Woerner, C. V.

    1978-01-01

    The overall program objective of the Earth Radiation Budget Satellite System is to gather the required radiation budget data and apply these data for a better understanding and prediction of climate. The paper describes the planned system, including the instruments and the associated sampling strategies and data analysis methods. Examination of mission implications reveals the need for a multisensor, multisatellite system consisting of high- and mid-inclination orbits. Each spacecraft will carry wide and medium field-of-view sensors, a sensor for measuring the solar constant, and a narrow field-of-view cross-track scanner.

  1. Hafnium and iron isotopes in early Archean komatiites record a plume-driven convection cycle in the Hadean Earth

    Science.gov (United States)

    Nebel, Oliver; Campbell, Ian H.; Sossi, Paolo A.; Van Kranendonk, Martin J.

    2014-07-01

    Archean (>2.5 billion years) komatiites are considered expressions of mantle plumes that originate from and thereby sample the lowermost mantle overlying the Earth's core. Some komatiites have reported Hf isotope signatures that require a mantle source with a time-integrated Lu/Hf that is appreciably higher than average modern depleted mantle. The systematic study of the time and locus of parent-daughter fractionation of the mantle sources of these komatiites potentially constrains differentiation processes in the early Earth, and subsequent distribution and storage of early mantle reservoirs. We present radiogenic Hf and stable Fe isotopes for a series of komatiites from the Pilbara craton in Western Australia (aged 3.5 to 2.9 Ga). After careful evaluation of the effects of alteration, we find that pristine samples are characterised by a light Fe isotope mantle source and initial 176Hf/177Hf well above the age-corrected depleted mantle. Taken together these observations require a component of an old, melt-depleted reservoir in their mantle source. The Hf isotope signature of this component appears to be complementary to the first terrestrial crust, as preserved in Hadean (i.e., >4 Ga) detrital zircon cores, suggesting a causal relationship and a Hadean age for this depletion event. We propose that this Early Refractory Reservoir (ERR) is the residue formed by deep melting in hot Hadean mantle plumes, which then accumulated at the base of the first crust. Parts of this primordial lithosphere were destabilised and sank to the core-mantle boundary in cold drips and subsequently returned in hot mantle plumes, whose thermal capacity allows melting of such refractory mantle with its archetype isotope signature. The cycling of this material via cold drips and hot plumes suggests a plume-dominated convection prior to ∼3.9 Ga, which is then replaced by Archean-style plate tectonics.

  2. Earth's early fossil record: Why not look for similar fossils on Mars?

    Science.gov (United States)

    Awramik, Stanley M.

    1989-01-01

    The oldest evidence of life on Earth is discussed with attention being given to the structure and formation of stromatolites and microfossils. Fossilization of microbes in calcium carbonate or chert media is discussed. In searching for fossil remains on Mars, some lessons learned from the study of Earth's earliest fossil record can be applied. Certain sedimentary rock types and sedimentary rock configurations should be targeted for investigation and returned by the Martian rover and ultimately by human explorers. Domical, columnar to wavy laminated stratiform sedimentary rocks that resemble stromatolites should be actively sought. Limestone, other carbonates, and chert are the favored lithology. Being macroscopic, stromatolites might be recognized by an intelligent unmanned rover. In addition, black, waxy chert with conchoidal fracture should be sought. Chert is by far the preferred lithology for the preservation of microbes and chemical fossils. Even under optimal geological conditions (little or no metamorphism or tectonic alteration, excellent outcrops, and good black chert) and using experienced field biogeologists, the chances of finding well preserved microbial remains in chert are very low.

  3. Iron oxides, divalent cations, silica, and the early earth phosphorus crisis

    DEFF Research Database (Denmark)

    Jones, C.; Nomosatryo, S.; Crowe, S.A.;

    2015-01-01

    and silica content of BIFs, we estimate that seawater in the Archean and early Proterozoic Eons likely contained 0.04–0.13 µM phosphorus, on average. These phosphorus limiting conditions could have favored primary production through photoferrotrophy at the expense of oxygenic photosynthesis until upwelling......As a nutrient required for growth, phosphorus regulates the activity of life in the oceans. Iron oxides sorb phosphorus from seawater, and through the Archean and early Proterozoic Eons, massive quantities of iron oxides precipitated from the oceans, producing a record of seawater chemistry...

  4. Cuatro Ciénegas Basin an analog of precambrian Earth and possible early mars scenario. (Invited)

    Science.gov (United States)

    Souza, V.; Eguiarte, L. E.; Sierfert, J.

    2010-12-01

    In the present, the Cuatro Cienegas Basin (CCB) is in the Chihuahuan Desert in the state of Coahuila, Mexico. However, in the early Triasic, the sea penetrated the region of CCB with the opening of Pangea and became a continental wetland with the closing the western interior seaway only 35 million years ago. Its particular tectonics made of CCB a valley surrounded by high sierras that rose above the sea level 700 mt. All available molecular data lead us to suggest that these ancient marine microbial mats have persisted for a very long time and during all that time, the living microbial community evolved and diversified locally due to the rarity of migration and sex. The struggle for life in these structured communities generated uncountable new species that had to deal with the environment, the neighbors and most of all with the extreme lack of P. What for a long time represented the most successful community assemblage in the history of planet Earth, became mostly extinct in modern earth. The herbivores and the competition with algae left few relict communities in extreme environments such as CCB, Shark Bay and Guerrero Negro. Lets remember that stromatolite reefs have fossils as old as 3.6 billion years and that they became so successful that they changed the planet atmosphere producing the great oxygenation event. We also have data that at CCB these extensive microbialites are very patchy and differentiated both taxonomically and genetically, implying that, even though they may look as a continuum in the wetlands, each patch has been geographically isolated for a long time allowing each community to diverge in its composition. All these particularities of CCB arise because, due to its unusual geology, the valley floor was never buried, hence its marine sediment, with extensive microbial mats, always had sun and water, maintaining both the ancient lineages and the oligotrophic conditions that characterized early earth. The lack of P (less than 0.05 n

  5. The tungsten isotopic composition of Eoarchean rocks: Implications for early silicate differentiation and core-mantle interaction on Earth

    Science.gov (United States)

    Iizuka, Tsuyoshi; Nakai, Shun'ichi; Sahoo, Yu Vin; Takamasa, Asako; Hirata, Takafumi; Maruyama, Shigenori

    2010-03-01

    We have measured 182W/ 184W for Eoarchean rocks from the Itsaq Gneiss Complex (3.8-3.7 Ga pillow meta-basalts, a meta-tonalite, and meta-sediments) and Acasta Gneiss Complex (4.0-3.6 Ga felsic orthogneisses) to assess possible W isotopic heterogeneity within the silicate Earth and to constrain W isotopic evolution of the mantle. The data reveal that 182W/ 184W values in the Eoarchean samples are uniform within the analytical error and indistinguishable from the modern accessible mantle signature, suggesting that the W isotopic composition of the upper mantle has not changed significantly since the Eoarchean era. The results imply either that chemical communication between the mantle and core has been insignificant in post-Hadean times, or that a lowermost mantle with a distinctive W isotope signature has been isolated from mantle convective cycling. Most terrestrial rock samples have a 0.2 ɛ142Nd/ 144Nd higher than the chondrite average. This requires either the presence of a hidden enriched reservoir formed within the first 30 Ma of the Solar System, or the bulk Earth having a ˜ 5% higher Sm/Nd than the chondrite average. We explored the relevance of the 182Hf- 182W isotope system to the 146Sm- 142Nd isotope system during early silicate differentiation events on Earth. In this context, we demonstrate that the lack of resolvable 182W excesses in the Itsaq rocks, despite 142Nd excesses compared to the modern accessible mantle, is more consistent with the view that the bulk Earth has a non-chondritic Sm/Nd. In the non-chondritic Sm/Nd Earth model, the 182W- 142Nd chronometry constrains the age of the source mantle depletion for the Itsaq samples to more than ˜ 40 Ma after the Solar System origin. Our results cannot confirm the previous report of 182W anomalies in the Eoarchean Itsaq meta-sediments, which were interpreted as reflecting an impact-derived meteoritic component.

  6. Early history of Earth's crust-mantle system inferred from hafnium isotopes in chondrites

    DEFF Research Database (Denmark)

    Bizzarro, Martin; Haack, Henning; Rosing, M.;

    2003-01-01

    depleted mantle reservoir. Here we report Lu-Hf isotope measurements of different Solar System objects including chondrites and basaltic eucrites. The chondrites define a Lu-Hf isochron with an initial Hf/Hf ratio of 0.279628 ± 0.000047, corresponding to ¿176 = 1.983 ± 0.033 x 10yr using an age of 4.56 Gyr...... for the chondrite-forming event. This ¿176 value indicates that Earth's oldest minerals were derived from melts of a mantle source with a time-integrated history of depletion rather than enrichment. The depletion event must have occurred no later than 320 Myr after planetary accretion, consistent with timing...

  7. Building the Next Generation of Earth Scientists: the Deep Carbon Observatory Early Career Scientist Workshops

    Science.gov (United States)

    Pratt, K.; Fellowes, J.; Giovannelli, D.; Stagno, V.

    2016-12-01

    Building a network of collaborators and colleagues is a key professional development activity for early career scientists (ECS) dealing with a challenging job market. At large conferences, young scientists often focus on interacting with senior researchers, competing for a small number of positions in leading laboratories. However, building a strong, international network amongst their peers in related disciplines is often as valuable in the long run. The Deep Carbon Observatory (DCO) began funding a series of workshops in 2014 designed to connect early career researchers within its extensive network of multidisciplinary scientists. The workshops, by design, are by and for early career scientists, thus removing any element of competition and focusing on peer-to-peer networking, collaboration, and creativity. The successful workshops, organized by committees of early career deep carbon scientists, have nucleated a lively community of like-minded individuals from around the world. Indeed, the organizers themselves often benefit greatly from the leadership experience of pulling together an international workshop on budget and on deadline. We have found that a combination of presentations from all participants in classroom sessions, professional development training such as communication and data management, and field-based relationship building and networking is a recipe for success. Small groups within the DCO ECS network have formed; publishing papers together, forging new research directions, and planning novel and ambitious field campaigns. Many DCO ECS also have come together to convene sessions at major international conferences, including the AGU Fall Meeting. Most of all, there is a broad sense of camaraderie and accessibility within the DCO ECS Community, providing the foundation for a career in the new, international, and interdisciplinary field of deep carbon science.

  8. Simulation of Prebiotic Processing by Comet and Meteoroid Impact: Implications for Life on Early Earth and Other Planets

    Science.gov (United States)

    Dateo, Christopher E.

    2003-01-01

    We develop a reacting flow model to simulate the shock induced chemistry of comets and meteoroids entering planetary atmospheres. Various atmospheric compositions comprising of simpler molecules (i.e., CH4, CO2, H2O, etc.) are investigated to determine the production efficiency of more complex prebiotic molecules as a function of composition, pressure, and entry velocity. The possible role of comets and meteoroids in creating the inventory of prebiotic material necessary for life on Early Earth is considered. Comets and meteoroids can also introduce new materials from the Interstellar Medium (ISM) to planetary atmospheres. The ablation of water from comets, introducing the element oxygen into Titan's atmosphere will also be considered and its implications for the formation of organic and prebiotic material.

  9. Insights into the behaviour of biomolecules on the early Earth: The concentration of aspartate by layered double hydroxide minerals

    Science.gov (United States)

    Grégoire, Brian; Erastova, Valentina; Geatches, Dawn L.; Clark, Stewart J.; Greenwell, H. Christopher; Fraser, Donald G.

    2016-03-01

    The role of mineral surfaces in concentrating and facilitating the polymerisation of simple protobiomolecules during the Hadean and Archean has been the subject of much research in order to constrain the conditions that may have led to the origin of life on early Earth. Here we examine the adsorption of the amino acid aspartate on layered double hydroxide minerals, and use a combined computer simulation - experimental spectroscopy approach to gain insight into the resulting structures of the host-aspartate material. We show that the uptake of aspartate occurs in alkaline solution by anion exchange of the dianion form of aspartate, rather than by surface adsorption. Anion exchange only occurs at values of pH where a significant population of aspartate has the amino group deprotonated, and is then highly efficient up to the mineral anion exchange capacity.

  10. Simulation of Prebiotic Processing by Comet and Meteoroid Impact: Implications for Life on Early Earth and Other Planets

    Science.gov (United States)

    Dateo, Christopher E.

    2003-01-01

    We develop a reacting flow model to simulate the shock induced chemistry of comets and meteoroids entering planetary atmospheres. Various atmospheric compositions comprising of simpler molecules (i.e., CH4, CO2, H2O, etc.) are investigated to determine the production efficiency of more complex prebiotic molecules as a function of composition, pressure, and entry velocity. The possible role of comets and meteoroids in creating the inventory of prebiotic material necessary for life on Early Earth is considered. Comets and meteoroids can also introduce new materials from the Interstellar Medium (ISM) to planetary atmospheres. The ablation of water from comets, introducing the element oxygen into Titan's atmosphere will also be considered and its implications for the formation of organic and prebiotic material.

  11. Determination of rare earth and refractory trace element abundances in early solar system objects by ion microprobe

    Indian Academy of Sciences (India)

    S Sahijpal; K K Marhas; J N Goswami

    2003-12-01

    Experimental and analytical procedures devised for measurement of rare earth element (REE) abundances using a secondary ion mass spectrometer (ion microprobe) are described. This approach is more versatile than the conventional techniques such as neutron activation analysis and isotope dilution mass spectrometry by virtue of its high spatial resolution that allows determination of REE abundances in small domains (10-20 micron) within individual mineral phases. The ion microprobe measurements are performed at a low mass-resolving power adopting the energy-filltering technique (Zinner and Crozaz 1986) for removal and suppression of unresolved complex molecular interferences in the REE masses of interest. Synthetic standards are used for determining various instrument specific parameters needed in the data deconvolution procedure adopted for obtaining REE abundances. Results obtained from analysis of standards show that our ion microprobe may be used for determining REE abundances down to ppm range with uncertainties of ∼10 to 15%. Abundances of rare earth and several other refractory trace elements in a set of early solar system objects isolated from two primitive carbonaceous chondrites were determined using the procedures devised by us. The results suggest that some of these objects could be high temperature nebular condensates, while others are products of melting and recrystallization of precursor nebular solids in a high temperature environment.

  12. Peptide synthesis triggered by comet impacts: A possible method for peptide delivery to the early Earth and icy satellites

    Science.gov (United States)

    Sugahara, Haruna; Mimura, Koichi

    2015-09-01

    We performed shock experiments simulating natural comet impacts in an attempt to examine the role that comet impacts play in peptide synthesis. In the present study, we selected a mixture of alanine (DL-alanine), water ice, and silicate (forsterite) to make a starting material for the experiments. The shock experiments were conducted under cryogenic conditions (77 K), and the shock pressure range achieved in the experiments was 4.8-25.8 GPa. The results show that alanine is oligomerized into peptides up to tripeptides due to the impact shock. The synthesized peptides were racemic, indicating that there was no enantioselective synthesis of peptides from racemic amino acids due to the impact shock. We also found that the yield of linear peptides was a magnitude higher than those of cyclic diketopiperazine. Furthermore, we estimated the amount of cometary-derived peptides to the early Earth based on two models (the Lunar Crating model and the Nice model) during the Late Heavy Bombardment (LHB) using our experimental data. The estimation based on the Lunar Crating model gave 3 × 109 mol of dialanine, 4 × 107 mol of trialanine, and 3 × 108 mol of alanine-diketopiperazine. Those based on the Nice model, in which the main impactor of LHB is comets, gave 6 × 1010 mol of dialanine, 1 × 109 mol of trialanine, and 8 × 109 mol of alanine-diketopiperazine. The estimated amounts were comparable to those originating from terrestrial sources (Cleaves, H.J., Aubrey, A.D., Bada, J.L. [2009]. Orig. Life Evol. Biosph. 39, 109-126). Our results indicate that comet impacts played an important role in chemical evolution as a supplier of linear peptides, which are important for further chemical evolution on the early Earth. Our study also highlights the importance of icy satellites, which were formed by comet accumulation, as prime targets for missions searching for extraterrestrial life.

  13. Evolutionary Competition Between Primitive Photosynthetic Systems: Existence of an early purple Earth?

    Science.gov (United States)

    Sparks, William B.; DasSarma, S.; Reid, I. N.

    2006-12-01

    The onset of photosynthesis in primitive cyanobacteria is thought to have profoundly altered the Earth’s atmosphere by producing an oxygen-rich atmosphere some 2 billion years ago. However, the pigments used by chlorophyll-based photosynthesis absorb at a variety of wavelengths, curiously except those centered around the peak of the Solar spectrum, 550nm. By contrast, simpler retinal-based light harvesting systems such as the haloarchaeal purple membrane bacteriorhodopsin and halorhodopsin show a strong well-defined peak of absorbance centered at 550nm. The spectroscopic complementarity for retinal pigments with chlorophyll-based pigments suggests an intriguing possibility of their co-evolution. This hypothesis argues that simpler retinal-based phototrophic capability may have evolved earlier, in microorganisms that dominated during the anaerobic and purple phase of the planet. Later, the more complex chlorophyll-based photosystem pigments could have evolved to harvest light in regions of the spectrum not absorbed by preexisting species. This would have led to the greening and oxidation of our planet and displacement of most of the retinal-based microorganisms. Not surprisingly, evidence for retinal chromoproteins have recently turned up in a variety of planktonic microorganisms. Although speculative, such a scenario would indicate that retinal-based phototrophy may be one of the oldest metabolic capabilities on Earth. Moreover, if the chlorophyll absorption spectrum is simply a product of adaptation, then its utility as a potential biomarker is likely to be limited.

  14. Chondrite barium, neodymium, and samarium isotopic heterogeneity and early Earth differentiation.

    Science.gov (United States)

    Carlson, Richard W; Boyet, Maud; Horan, Mary

    2007-05-25

    Isotopic variability in barium, neodymium, and samarium in carbonaceous chondrites reflects the distinct stellar nucleosynthetic contributions to the early solar system. We used 148Nd/144Nd to correct for the observed s-process deficiency, which produced a chondrite 146Sm-142Nd isochron consistent with previous estimates of the initial solar system abundance of 146Sm and a 142Nd/144Nd at average chondrite Sm/Nd ratio that is lower than that measured in terrestrial rocks by 21 +/- 3 parts per million. This result strengthens the conclusion that the deficiency in 142Nd in chondrites relative to terrestrial rocks reflects 146Sm decayand earlyplanetary differentiation processes.

  15. Evolution of Electron Transport Chains During the Anaerobic to Aerobic Transition on Early Earth

    Science.gov (United States)

    Sepúlveda, R.; Ortiz, R.; Holmes, D. S.

    2015-12-01

    Sepulveda, R., Ortiz R. and Holmes DS. Center for Bioinformatics and Genome Biology, Fundacion Ciencia y Vida, and Facultad de Ciencias Biologicas, Universidad Andres Bello, Santiago, Chile.According to several models, life emerged on earth in an anoxic environment where oxygen was not available as a terminal electron acceptor for energy generating reactions. After the Great Oxidation Event (GOE) about 2.4 billion years ago, or perhaps even before the GOE, oxygen became the most widespread and efficient terminal electron acceptor and was accompanied by the evolution of a number of redox proteins that could deliver electrons to reduce oxygen to water. Where did these proteins come from? One hypothesis is that they evolved by the neofunctionalization of previously existing redox proteins that had been used in anaerobic conditions as terminal electron donors to reduce compounds such as perchlorate, nitric oxide or iron. We have used a number of bioinformatic tools to explore a large number of genomes looking for discernable signals of such redeployment of function. A Perl pipeline was designed to detect sequence similarity, conserved gene context, remote homology detection, identification of domains and functional evolution of electron carrier proteins from extreme acidophiles, including the small blue copper protein rusticyanin (involved in FeII oxidation), cytochrome oxidase subunit II and quinol-dependent nitric oxide reductase (qNOR). The protein folds and copper binding sites of rusticyanin are conserved in cytochrome oxidase aa3 subunit II, a protein complex that is responsible for the final passage of electrons to reduce oxygen. Therefore, we hypothesize that rusticyanin, cytochrome oxidase II and qNOR are evolutionarily related. Acknowledgments: Fondecyt 1130683.

  16. First Impressions (Primeras Impresiones): Report of the Task Force on Early Childhood and Elementary Education [with] Executive Summary (Sintesis Ejecutiva).

    Science.gov (United States)

    Texas Education Agency, Austin.

    The Task Force on Early Childhood and Elementary Education, created by the Texas State Board of Education in January 1993, found that the current system of early childhood and elementary education is struggling to meet the challenges of childhood in today's Texas. This report summarizes the task force's call for schools to reconfigure themselves…

  17. Early aerial photography and contributions to Digital Earth - The case of the 1921 Halifax air survey mission in Canada

    Science.gov (United States)

    Werle, D.

    2016-04-01

    This paper presents research into the military and civilian history, technological development, and practical outcomes of aerial photography in Canada immediately after the First World War. The collections of early aerial photography in Canada and elsewhere, as well as the institutional and practical circumstances and arrangements of their creation, represent an important part of remote sensing heritage. It is argued that the digital rendition of the air photos and their representation in mosaic form can make valuable contributions to Digital Earth historic inquiries and mapping exercises today. An episode of one of the first urban surveys, carried out over Halifax, Nova Scotia, in 1921, is highlighted and an air photo mosaic and interpretation key is presented. Using the almost one hundred year old air photos and a digitally re-assembled mosaic of a substantial portion of that collection as a guide, a variety of features unique to the post-war urban landscape of the Halifax peninsula are analysed, illustrated, and compared with records of past and current land use. The pan-chromatic air photo ensemble at a nominal scale of 1:5,000 is placed into the historical context with contemporary thematic maps, recent air photos, and modern satellite imagery. Further research opportunities and applications concerning early Canadian aerial photography are outlined.

  18. Symbiosis in cell evolution: Life and its environment on the early earth

    Science.gov (United States)

    Margulis, L.

    1981-01-01

    The book treats cell evolution from the viewpoint of the serial endosymbiosis theory of the origin of organelles. Following a brief outline of the symbiotic theory, which holds that eukaryotes evolved by the association of free-living bacteria with a host prokaryote, the diversity of life is considered, and five kingdoms of organisms are distinguished: the prokaryotic Monera and the eukaryotic Protoctista, Animalia, Fungi and Plantae. Symbiotic and traditional direct filiation theories of cell evolution are compared. Recent observations of cell structure and biochemistry are reviewed in relation to early cell evolution, with attention given to the geological context for the origin of eukaryotic cells, the origin of major bacterial anaerobic pathways, the relationship between aerobic metabolism and atmospheric oxygen, criteria for distinguishing symbiotic organelles from those that originated by differentiation, and the major classes of eukaryotic organelles: mitochondria, cilia, microtubules, the mitotic and meiotic apparatuses, and pastids. Cell evolution during the Phanerozoic is also discussed with emphasis on the effects of life on the biosphere

  19. Early Mission Orbit Determination Error Analysis Results for Low-Earth Orbiting Missions using TDRSS Differenced One-way Doppler Tracking Data

    Science.gov (United States)

    Marr, Greg C.

    2003-01-01

    Differencing multiple, simultaneous Tracking and Data Relay Satellite System (TDRSS) one-way Doppler passes can yield metric tracking data usable for orbit determination for (low-cost) spacecraft which do not have TDRSS transponders or local oscillators stable enough to allow the one-way TDRSS Doppler tracking data to be used for early mission orbit determination. Orbit determination error analysis results are provided for low Earth orbiting spacecraft for various early mission tracking scenarios.

  20. Deep Reaching Gas-permeable Tectonic Faults of the Early Earth as Habitats for the Origin of Life

    Science.gov (United States)

    Schreiber, U.; Mayer, C.

    2012-04-01

    The discussion on the origin of life encounters difficulties when it comes to estimate the conditions of the early earth and to define plausible environments for the development of the first complex organic molecules. Until now, the role of the earth's crust has been more or less ignored. First continental crustal cores may have been developed some tens to hundreds of million years after formation of earth. Due to tectonic stress the proto continents were sheared by vertical strike-slip faults at an early stage. These deep-reaching open, interconnected tectonic faults may provide possible reaction habitats ranging from nano- to centimetre and even larger dimensions that sum up to several cubic kilometres for the formation of prebiotic molecules. Their fillings consist of supercritical and subcritical waters and supercritical and subcritical gases. Here, all necessary raw materials including phosphate for the development of prebiotic molecules exist in variable concentrations and in sufficient quantities. Furthermore, there are periodically changing pressure and temperature conditions, varying pH-values, metallic surfaces, clay minerals and a large number of catalysts. While cosmic and UV-radiation are excluded, nuclear radiation intervenes the chemical evolution of the molecules inside the crust. Carbon dioxide (CO2) is of crucial importance. It can be present in an almost pure form as a supercritical fluid (scCO2) in a crustal depth less than 1 km (critical point of pure CO2: 74 bar; 31°C). Inside strike-slip faults, a two-phase system formed by supercritical CO2 in liquid water provides the environment for condensation and polymerisation of hydrogen cyanide, nucleobases, nucleotides and amino acids. ScCO2 is a non-polar solvent that is widely used in "green chemistry" (Anastas and Kirchhoff 2002) and enables the dissolution of non-polar reactants and their reactions normally occurring in the absence of water. Under the influence of periodically changing

  1. An Agro-Climatological Early Warning Tool Based on the Google Earth Engine to Support Regional Food Security Analysis

    Science.gov (United States)

    Landsfeld, M. F.; Daudert, B.; Friedrichs, M.; Morton, C.; Hegewisch, K.; Husak, G. J.; Funk, C. C.; Peterson, P.; Huntington, J. L.; Abatzoglou, J. T.; Verdin, J. P.; Williams, E. L.

    2015-12-01

    The Famine Early Warning Systems Network (FEWS NET) focuses on food insecurity in developing nations and provides objective, evidence based analysis to help government decision-makers and relief agencies plan for and respond to humanitarian emergencies. The Google Earth Engine (GEE) is a platform provided by Google Inc. to support scientific research and analysis of environmental data in their cloud environment. The intent is to allow scientists and independent researchers to mine massive collections of environmental data and leverage Google's vast computational resources to detect changes and monitor the Earth's surface and climate. GEE hosts an enormous amount of satellite imagery and climate archives, one of which is the Climate Hazards Group Infrared Precipitation with Stations dataset (CHIRPS). The CHIRPS dataset is land based, quasi-global (latitude 50N-50S), 0.05 degree resolution, and has a relatively long term period of record (1981-present). CHIRPS is on a continuous monthly feed into the GEE as new data fields are generated each month. This precipitation dataset is a key input for FEWS NET monitoring and forecasting efforts. FEWS NET intends to leverage the GEE in order to provide analysts and scientists with flexible, interactive tools to aid in their monitoring and research efforts. These scientists often work in bandwidth limited regions, so lightweight Internet tools and services that bypass the need for downloading massive datasets to analyze them, are preferred for their work. The GEE provides just this type of service. We present a tool designed specifically for FEWS NET scientists to be utilized interactively for investigating and monitoring for agro-climatological issues. We are able to utilize the enormous GEE computing power to generate on-the-fly statistics to calculate precipitation anomalies, z-scores, percentiles and band ratios, and allow the user to interactively select custom areas for statistical time series comparisons and predictions.

  2. Diapirism on Venus and the Early Earth and The thermal effect of fluid flows in AECL's Tunnel Sealing Experiment

    Science.gov (United States)

    Robin, Catherine M. I.

    2010-12-01

    Flow instabilities occur at all scales in planetary systems. In this thesis we examine three cases of such instabilities, on three very different length scales. In the first part, we test the idea that Archean granite-greenstone belts (GGBs) form by crustal diapirism, or Rayleigh-Taylor instabilities. GGBs are characterized by large granitic domes (50-100 km in diameter) embedded in narrow keel-shaped greenstones. They are ubiquitous in Archean (> 2.5 Ga) terrains, but rare thereafter. We performed finite element calculations for a visco-elastic, temperature-dependent, non-Newtonian crust under conditions appropriate for the Archean, which show that dense low-viscosity volcanics overlying a felsic basement will overturn diapirically in as little as 10 Ma, displacing as much as 60 % of the volcanics to the lower crust. This surprisingly fast overturn rate suggests that diapiric overturn dominated crustal tectonics in the hot conditions of the Early Earth, becoming less important as the Earth cooled. Moreover, the deposition of large volumes of wet basaltic volcanics to the lower crust may provide the source for the formation of the distinctly Archean granitic rocks which dominate Earth's oldest continents. The second part examines the origin of Venusian coronae, circular volcanic features unique to Venus. Coronae are thought to result from small instabilities (diapirs) from the core-mantle boundary, which are typical of stagnant-lid convection. However, most young coronae are located in a region surrounded by long-lived hotspots, typical of a more active style of mantle convection. Using analogue experiments in corn syrup heated from below, we show that the co-existence of diapirs and long-lived mantle plumes are a direct consequence of the catastrophic overturn of the cold Venusian lithosphere thought to have occurred ˜ 700 Ma ago. In the last part we analyze the thermal effect of fluid flow through a full-scale experiment testing clay and concrete tunnel seals in

  3. Ancient Maya impacts on the Earth's surface: An Early Anthropocene analog?

    Science.gov (United States)

    Beach, Tim; Luzzadder-Beach, Sheryl; Cook, Duncan; Dunning, Nicholas; Kennett, Douglas J.; Krause, Samantha; Terry, Richard; Trein, Debora; Valdez, Fred

    2015-09-01

    The measure of the "Mayacene," a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the "Mayacene" are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3-dominated tropical forest ecosystem. Paleosol sequences exhibit "Maya Clays," a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize

  4. Earth rotation and geodynamics

    OpenAIRE

    Bogusz Janusz; Brzezinski Aleksander; Kosek Wieslaw; Nastula Jolanta

    2015-01-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals wit...

  5. Unfinished Business: Continued Investment in Child Care and Early Education Is Critical to Business and America's Future. Executive Summary

    Science.gov (United States)

    Committee for Economic Development, 2012

    2012-01-01

    Business leaders have an acute understanding of the importance of a well-educated workforce to support a strong economy, keep America competitive globally, and ensure a vibrant democracy. Right now 20 percent of the American labor force is functionally illiterate or innumerate. High-quality child care and early education builds a strong foundation…

  6. Illinois' Early Childhood Innovation Zones: A New Model for State Policy? IERC 2017-1. Executive Summary

    Science.gov (United States)

    White, Bradford R.; Colaninno, Carol E.; Doll, Mimi; Lewandowski, Holly

    2017-01-01

    This evaluation reviews efforts made by Illinois Action for Children (IAFC), with guidance from the Illinois Governor's Office for Early Childhood Development, to spur experimentation with new systemic change strategies to increase the number of children from priority populations--those considered to be the most vulnerable, with multiple risk…

  7. Optical Investigations of Rare-Earth Orthochromites. III. GdCrO3 and Summary of the R' Band in RCrO3

    Science.gov (United States)

    Kojima, Norimichi; Tsujikawa, Ikuji; Tsushima, Kuniro

    1985-12-01

    Optical absorption spectrum corresponding to the 4A2g→2Eg transition of Cr3+ in GdCrO3 was studied. The R' band was observed in the lower energy side of the R exciton band. The temperature and magnetic field dependences of the R' band imply that the R' band is the combined excitation of a Cr3+ exciton and a Gd3+ spin flip induced by the isotropic part of the Cr3+-Gd3+ exchange interaction. As the summary of the successive papers, the classification of the R' band in RCrO3(R=Yb, Tm, Er, No, Dy, Tb and Gd) was undertaken.

  8. Mixing in mantle convection models with self-consistent plate tectonics and melting and crustal production: Application to mixing in the early Earth

    Science.gov (United States)

    Tackley, Paul

    2016-04-01

    It is generally thought that the early Earth's mantle was hotter than today, which using conventional convective scalings should have led to vigorous convection and mixing. Geochemical observations, however, suggest that mixing was not as rapid as would be expected, leading to the suggestion that early Earth had stagnant lid convection (Debaille et al., EPSL 2013). Additionally, the mantle's thermal evolution is difficult to explain using conventional scalings because early heat loss would have been too rapid, which has led to the hypothesis that plate tectonics convection does not follow the conventional convective scalings (Korenaga, GRL 2003). One physical process that could be important in this context is partial melting leading to crustal production, which has been shown to have the major effects of buffering mantle temperature and carrying a significant fraction of the heat from hot mantle (Nakagawa and Tackley, EPSL 2012), making plate tectonics easier (Lourenco et al., submitted), and causing compositional differentiation of the mantle that can buffer core heat loss (Nakagawa and Tackley, GCubed 2010). Here, the influence of this process on mantle mixing is examined, using secular thermo-chemical models that simulate Earth's evolution over 4.5 billion years. Mixing is quantified both in terms of how rapidly stretching occurs, and in terms of dispersion: how rapidly initially close heterogeneities are dispersed horizontally and vertically through the mantle. These measures are quantified as a function of time through Earth's evolution. The results will then be related to geochemically-inferred mixing rates.

  9. Use of the Earth Observing One (EO-1) Satellite for the Namibia SensorWeb Flood Early Warning Pilot

    Science.gov (United States)

    Mandl, Daniel; Frye, Stuart; Cappelaere, Pat; Handy, Matthew; Policelli, Fritz; Katjizeu, McCloud; Van Langenhove, Guido; Aube, Guy; Saulnier, Jean-Francois; Sohlberg, Rob; Silva, Julie; Kussul, Nataliia; Skakun, Sergii; Ungar, Stephen; Grossman, Robert

    2012-01-01

    The Earth Observing One (EO-1) satellite was launched in November 2000 as a one year technology demonstration mission for a variety of space technologies. After the first year, it was used as a pathfinder for the creation of SensorWebs. A SensorWeb is the integration of variety of space, airborne and ground sensors into a loosely coupled collaborative sensor system that automatically provides useful data products. Typically, a SensorWeb is comprised of heterogeneous sensors tied together with a messaging architecture and web services. Disasters are the perfect arena to use SensorWebs. One SensorWeb pilot project that has been active since 2009 is the Namibia Early Flood Warning SensorWeb pilot project. The Pilot Project was established under the auspices of the Namibian Ministry of Agriculture Water and Forestry (MAWF)/Department of Water Affairs, the Committee on Earth Observing Satellites (CEOS)/Working Group on Information Systems and Services (WGISS) and moderated by the United Nations Platform for Space-based Information for Disaster Management and Emergency Response (UN-SPIDER). The effort began by identifying and prototyping technologies which enabled the rapid gathering and dissemination of both space-based and ground sensor data and data products for the purpose of flood disaster management and water-borne disease management. This was followed by an international collaboration to build small portions of the identified system which was prototyped during that past few years during the flood seasons which occurred in the February through May timeframe of 2010 and 2011 with further prototyping to occur in 2012. The SensorWeb system features EO-1 data along with other data sets from such satellites as Radarsat, Terra and Aqua. Finally, the SensorWeb team also began to examine the socioeconomic component to determine the impact of the SensorWeb technology and how best to assist in the infusion of this technology in lesser affluent areas with low levels of basic

  10. Earth Observations for Early Detection of Agricultural Drought in Countries at Risk: Contributions of the Famine Early Warning Systems Network (FEWS NET) (Invited)

    Science.gov (United States)

    Verdin, J. P.; Rowland, J.; Senay, G. B.; Funk, C. C.; Budde, M. E.; Husak, G. J.; Jayanthi, H.

    2013-12-01

    The Group on Earth Observations' Global Agricultural Monitoring (GEOGLAM) implementation plan emphasizes the information needs of countries at risk of food insecurity emergencies. Countries in this category are often vulnerable to disruption of agricultural production due to drought, while at the same time they lack well developed networks of in-situ observations to support early drought detection. Consequently, it is vital that Earth observations by satellites supplement those available from surface stations. The USGS, in its role as a FEWS NET implementing partner, has recently developed a number of new applications of satellite observations for this purpose. (1) In partnership with the University of California, Santa Barbara, a 30+ year time series of gridded precipitation estimates (CHIRPS) has been developed by blending NOAA GridSat B1 geostationary thermal infrared imagery with station observations using robust geostatistical methods. The core data set consists of pentadal (5-daily) accumulations from 1981-2013 at 0.05 degree spatial resolution between +/- 50 degrees latitude. Validation has been recently completed, and applications for gridded crop water balance calculations and mapping the Standardized Precipitation Index are in development. (2) Actual evapotranspiration (ETa) estimates using MODIS Land Surface Temperature (LST) data at 1-km have been successfully demonstrated using the operational Simplified Surface Energy Balance model with 8-day composites from the LPDAAC. A new, next-day latency implementation using daily LST swath data from the NASA LANCE server is in development for all the crop growing regions of the world. This ETa processing chain follows in the footsteps of (3) the expedited production of MODIS 250-meter NDVI images every five days at USGS EROS, likewise using LANCE daily swath data as input since 2010. Coverage includes Africa, Central Asia, the Middle East, Central America, and the Caribbean. (4) A surface water point monitoring

  11. PGE, Re-Os, and Mo isotope systematics in Archean and early Proterozoic sedimentary systems as proxies for redox conditions of the early Earth

    Science.gov (United States)

    Siebert, C.; Kramers, J. D.; Meisel, Th.; Morel, Ph.; Nägler, Th. F.

    2005-04-01

    Re-Os data and PGE concentrations as well as Mo concentrations and isotope data are reported for suites of fine clastic sediments and black shales from the Barberton Greenstone Belt, South Africa (Fig Tree and Moodies Groups, 3.25-3.15 Ga), the Belingwe Greenstone Belt, Zimbabwe (Manjeri Formation, ca. 2.7 Ga) and shales from the Witwatersrand, Ventersdorp and Transvaal Supergroups, South Africa ranging from 2.95 to 2.2 Ga. Moderately oxidizing conditions are required to mobilize Re and Mo in the environment, Mo fractionation only occurs in solution, and these parameters thus have potential use as paleoredox proxies for the early Earth. PGE + Re abundance patterns of Barberton Greenstone Belt sediments are uniform and very similar in shape to those of komatiites. This indicates (1) that the PGE came from a source of predominantly ultramafic composition and, (2) that PGE were transported and deposited essentially in particulate form. Sediments from the younger Belingwe Greenstone Belt show more fractionated PGE + Re patterns and have Re/Os ratios 10 to 100× higher than those of Barberton sediments. Their PGE abundance patterns and Re/Os ratios are intermediate between those of the mid-Archean shales and Neoproterozoic to Recent black shales. They reflect scavenging of Re from solution in the sedimentary environment. δ 98/95Mo values of black shales of all ages correlate with their concentrations. The Barberton Greenstone Belt samples have ˜1-3 ppm Mo, similar to a granitoid-basaltic source. This Mo has δ 98/95Mo between -1.9 and -2.4‰ relative to present day mean ocean water molybdenum, MOMO and is thus not isotopically fractionated relative to such a source. Similar to the PGE this indicates transport in solid form. Sediments from the Belingwe Greenstone Belt show in part enhanced Mo concentrations (up to 6 ppm) and Mo isotope fractionation (δ 98/95Mo up to -1.4‰ relative to MOMO). The combined PGE + Re and Mo data show mainly reducing conditions in the

  12. Toward understanding early Earth evolution: Prescription for approach from terrestrial noble gas and light element records in lunar soils

    OpenAIRE

    Ozima, Minoru; Yin, Qing-Zhu; Podosek, Frank A.; Miura, Yayoi N.

    2008-01-01

    Because of the almost total lack of geological record on the Earth's surface before 4 billion years ago, the history of the Earth during this period is still enigmatic. Here we describe a practical approach to tackle the formidable problems caused by this lack. We propose that examinations of lunar soils for light elements such as He, N, O, Ne, and Ar would shed a new light on this dark age in the Earth's history and resolve three of the most fundamental questions in earth science: the onset ...

  13. Geochemical evidence for active tropical serpentinization in the Santa Elena Ophiolite, Costa Rica: An analog of a humid early Earth?

    Science.gov (United States)

    Sánchez-Murillo, Ricardo; Gazel, Esteban; Schwarzenbach, Esther M.; Crespo-Medina, Melitza; Schrenk, Matthew O.; Boll, Jan; Gill, Ben C.

    2014-05-01

    is a planetary process that has important consequences on geochemical cycles, supporting microbial activity through the formation of H2 and CH4 and having the potential to sequester atmospheric CO2. We present geochemical evidence of active serpentinization in the Santa Elena Ophiolite, Costa Rica which is sustained by peridotites with a degree of serpentinization less than 50% with no evidence of an internal heat source. Average spring water temperatures are 29.1°C. Two hyperalkaline spring systems were discovered, with a spring fluid pH up to 11.18. The fluids are characterized by low Mg (1.0-5.9 mg/L) and K (1.0-5.5 mg/L) and relative high Ca (29-167 mg/L), Na (16-27 mg/L), Cl (26-29 mg/L), hydroxide (41-63 mg/L), and carbonate (31-49 mg/L). Active CH4 (24.3% v/v) vents coupled with carbonate deposits (δ13CCO2 =-27 to -14‰; δ18OCO2 =-17 to - 6‰) also provide evidence for active serpentinization and carbonation. Isotope ratios of the alkaline fluids (δ18O = -7.9‰, δ2H = -51.4‰) and groundwater (δ18O = -7.6‰; δ2H = -48.0‰) suggests that, during base flow recession, springs are fed by groundwater circulation. Methanogenic Archaea, which comprises a relatively high percentage of the 16S rRNA gene tag sequences, suggests that biological methanogenesis may play a significant role in the system. Santa Elena's extreme varying weather results in a scenario that could be of significant importance for (a) improving the knowledge of conditions on a humid early Earth or Mars that had periodic changes in water supply, (b) revealing new insights on serpentinizing solute transport, and (c) modeling hydrogeochemical responses as a function of recharge.

  14. "Supporting Early Career Women in the Geosciences through Online Peer-Mentoring: Lessons from the Earth Science Women's Network (ESWN)"

    Science.gov (United States)

    Holloway, T.; Hastings, M. G.; Barnes, R. T.; Fischer, E. V.; Wiedinmyer, C.; Rodriguez, C.; Adams, M. S.; Marin-Spiotta, E.

    2014-12-01

    The Earth Science Women's Network (ESWN) is an international peer-mentoring organization with over 2000 members, dedicated to career development and community for women across the geosciences. Since its formation in 2002, ESWN has supported the growth of a more diverse scientific community through a combination of online and in-person networking activities. Lessons learned related to online networking and community-building will be presented. ESWN serves upper-level undergraduates, graduate students, professionals in a range of environmental fields, scientists working in federal and state governments, post-doctoral researchers, and academic faculty and scientists. Membership includes women working in over 50 countries, although the majority of ESWN members work in the U.S. ESWN increases retention of women in the geosciences by enabling and supporting professional person-to-person connections. This approach has been shown to reduce feelings of isolation among our members and help build professional support systems critical to career success. In early 2013 ESWN transitioned online activities to an advanced social networking platform that supports discussion threads, group formation, and individual messaging. Prior to that, on-line activities operated through a traditional list-serve, hosted by the National Center for Atmospheric Research (NCAR). The new web center, http://eswnonline.org, serves as the primary forum for members to build connections, seek advice, and share resources. For example, members share job announcements, discuss issues of work-life balance, and organize events at professional conferences. ESWN provides a platform for problem-based mentoring, drawing from the wisdom of colleagues across a range of career stages.

  15. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  16. Early detection of cervical cancer with visual inspection methods: a summary of completed and on-going studies in India

    Directory of Open Access Journals (Sweden)

    Sankaranarayanan R

    2003-01-01

    Full Text Available India is a high-risk country for cervical cancer which accounts a quarter (126 000 new cases, 71 000 deaths around 2 000 of the world burden. The age-standardized incidence rates range from 16-55 per 100 000 women in different regions with particularly high rates in rural areas. Control of cervical cancer by early detection and treatment is a priority of the National Cancer Control Programme of India. There are no organized cytology screening programmes in the country. The technical and financial constraints to organize cytology screening have encouraged the evaluation of visual inspection approaches as potential alternatives to cervical cytology in India. Four types of visual detection approaches for cervical neoplasia are investigated in India: a naked eye inspection without acetic acid application, widely known as 'downstaging'; b naked eye inspection after application of 3-5% acetic acid (VIA; c VIA using magnification devices (VIAM; d visual inspection after the application of Lugol's iodine (VILI. Downstaging has been shown to be poorly sensitive and specific to detect cervical neoplasia and is no longer considered as a suitable screening test for cervical cancer. VIA, VIAM and VILI are currently being investigated in multicentre cross-sectional studies (without verification bias, in which cytology and HPV testing are also simultaneously evaluated, and the results of these investigations will be available in 2003. These studies will provide valuable information on the average, comparative test performances in detecting high-grade cervical cancer precursors and cancer. Results from pooled analysis of data from two completed studies indicated an approximate sensitivity of 93.4% and specificity of 85.1% for VIA to detect CIN 2 or worse lesions; the corresponding figures for cytology were 72.1% and 91.6%. The efficacy of VIA in reducing incidence of and mortality from cervical cancer and its cost-effectiveness is currently being investigated

  17. Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.

    2011-01-01

    This article presents summaries of three articles relevant to school crisis response: (1) "Factors Contributing to Posttraumatic Growth," summarized by Steve DeBlois; (2) "Psychological Debriefing in Cross-Cultural Contexts" (Stacey Rice); and (3) "Brain Abnormalities in PTSD" (Sunny Windingstad). The first summary reports the findings of a…

  18. Habitat of early life: Solar X-ray and UV radiation at Earth's surface 4-3.5 billion years ago

    CERN Document Server

    Cnossen, I; Favata, F; Witasse, O; Zegers, T; Arnold, N F

    2007-01-01

    Solar X-ray and UV radiation (0.1-320 nm) received at Earth's surface is an important aspect of the circumstances under which life formed on Earth. The quantity that is received depends on two main variables: the emission of radiation by the young Sun and its extinction through absorption and scattering by the Earth's early atmosphere. The spectrum emitted by the Sun when life formed, between 4 and 3.5 Ga, was modeled here, including the effects of flares and activity cycles, using a solar-like star that has the same age now as the Sun had 4-3.5 Ga. Atmospheric extinction was calculated using the Beer-Lambert law, assuming several density profiles for the atmosphere of the Archean Earth. We found that almost all radiation with a wavelength shorter than 200 nm is attenuated effectively, even by very tenuous atmospheres. Longer-wavelength radiation is progressively less well attenuated, and its extinction is more sensitive to atmospheric composition. Minor atmospheric components, such as methane, ozone, water v...

  19. Meteorite zircon constraints on the bulk Lu-Hf isotope composition and early differentiation of the Earth.

    Science.gov (United States)

    Iizuka, Tsuyoshi; Yamaguchi, Takao; Hibiya, Yuki; Amelin, Yuri

    2015-04-28

    Knowledge of planetary differentiation is crucial for understanding the chemical and thermal evolution of terrestrial planets. The (176)Lu-(176)Hf radioactive decay system has been widely used to constrain the timescales and mechanisms of silicate differentiation on Earth, but the data interpretation requires accurate estimation of Hf isotope evolution of the bulk Earth. Because both Lu and Hf are refractory lithophile elements, the isotope evolution can be potentially extrapolated from the present-day (176)Hf/(177)Hf and (176)Lu/(177)Hf in undifferentiated chondrite meteorites. However, these ratios in chondrites are highly variable due to the metamorphic redistribution of Lu and Hf, making it difficult to ascertain the correct reference values for the bulk Earth. In addition, it has been proposed that chondrites contain excess (176)Hf due to the accelerated decay of (176)Lu resulting from photoexcitation to a short-lived isomer. If so, the paradigm of a chondritic Earth would be invalid for the Lu-Hf system. Herein we report the first, to our knowledge, high-precision Lu-Hf isotope analysis of meteorite crystalline zircon, a mineral that is resistant to metamorphism and has low Lu/Hf. We use the meteorite zircon data to define the Solar System initial (176)Hf/(177)Hf (0.279781 ± 0.000018) and further to identify pristine chondrites that contain no excess (176)Hf and accurately represent the Lu-Hf system of the bulk Earth ((176)Hf/(177)Hf = 0.282793 ± 0.000011; (176)Lu/(177)Hf = 0.0338 ± 0.0001). Our results provide firm evidence that the most primitive Hf in terrestrial zircon reflects the development of a chemically enriched silicate reservoir on Earth as far back as 4.5 billion years ago.

  20. Survey Summary

    Data.gov (United States)

    U.S. Department of Health & Human Services — Nursing home summary information for the Health and Fire Safety Inspections currently listed on Nursing Home Compare, including dates of the three most recent...

  1. Meteorological Summaries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multi-year summaries of one or more meteorological elements at a station or in a state. Primarily includes Form 1078, a United States Weather Bureau form designed...

  2. Executive Summary

    DEFF Research Database (Denmark)

    Katritsis, Demosthenes G; Boriani, Giuseppe; Cosio, Francisco G

    2016-01-01

    This paper is an executive summary of the full European Heart Rhythm Association (EHRA) consensus document on the management of supraventricular arrhythmias, published in Europace. It summarises developments in the field and provides recommendations for patient management, with particular emphasi...

  3. Nonproteinogenic D-amino acids at millimolar concentrations are a toxin for anaerobic microorganisms relevant to early Earth and other anoxic planets.

    Science.gov (United States)

    Nixon, Sophie L; Cockell, Charles S

    2015-03-01

    The delivery of extraterrestrial organics to early Earth provided a potentially important source of carbon and energy for microbial life. Optically active organic compounds of extraterrestrial origin exist in racemic form, yet life on Earth has almost exclusively selected for L- over D-enantiomers of amino acids. Although D-enantiomers of proteinogenic amino acids are known to inhibit aerobic microorganisms, the role of concentrated nonproteinogenic meteoritic D-amino acids on anaerobic metabolisms relevant to early Earth and other anoxic planets such as Mars is unknown. Here, we test the inhibitory effect of D-enantiomers of two nonproteinogenic amino acids common to carbonaceous chondrites, norvaline and α-aminobutyric acid, on microbial iron reduction. Three pure strains (Geobacter bemidjiensis, Geobacter metallireducens, Geopsychrobacter electrodiphilus) and an iron-reducing enrichment culture were grown in the presence of 10 mM D-enantiomers of both amino acids. Further tests were conducted to assess the inhibitory effect of these D-amino acids at 1 and 0.1 mM. The presence of 10 mM D-norvaline and D-α-aminobutyric acid inhibited microbial iron reduction by all pure strains and the enrichment. G. bemidjiensis was not inhibited by either amino acid at 0.1 mM, but D-α-aminobutyric acid still inhibited at 1 mM. Calculations using published meteorite accumulation rates to the martian surface indicate D-α-aminobutyric acid may have reached inhibitory concentrations in little over 1000 years during peak infall. These data show that, on a young anoxic planet, the use of one enantiomer over another may render the nonbiological enantiomer an environmental toxin. Processes that generate racemic amino acids in the environment, such as meteoritic infall or impact synthesis, would have been toxic processes and could have been a selection pressure for the evolution of early racemases.

  4. Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

    Science.gov (United States)

    Kondo, Nozomi; Yoshino, Takashi; Matsukage, Kyoko N.; Kogiso, Tetsu

    2016-12-01

    The Accessible Silicate Earth (ASE) has a higher 142Nd/144Nd ratio than most chondrites. Thus, if the Earth is assumed to have formed from these chondrites, a complement low-142Nd/144Nd reservoir is needed. Such a low-142Nd/144Nd reservoir is believed to have been derived from a melt in the early Earth and is called the Early Enriched Reservoir (EER). Although the major element composition of the EER is crucial for estimating its chemical and physical properties (e.g., density) and is also essential for understanding the origin and fate of the EER, which are both major factors that determine the present composition of the Earth, it has not yet been robustly established. In order to determine the major element composition of the EER, we estimated the age and pressure-temperature conditions to form the EER that would best explain its Nd isotopic characteristics, based on Sm-Nd partitioning and its dependence on pressure, temperature, and melting phase relations. Our estimate indicates that the EER formed within 33.5 Myr of Solar System formation and at near-solidus temperatures and shallow upper-mantle pressures. We then performed high-pressure melting experiments on primitive peridotite to determine the major element composition of the EER at estimated temperature at 7 GPa and calculated the density of the EER. The result of our experiments indicates that the near-solidus melt is iron-rich komatiite. The estimated density of the near-solidus melt is lower than that of the primitive peridotite, suggesting that the EER melt would have ascended in the mantle to form an early crust. Given that high mantle potential temperatures are assumed to have existed in the Hadean, it follows that the EER melt was generated at high pressure and, therefore, its composition would have been picritic to komatiitic. As the formation age of the EER estimated in our study precedes the last giant, lunar-forming impact, the picritic to komatiitic crust (EER) would most likely have been

  5. Earth rotation and geodynamics

    Science.gov (United States)

    Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta

    2015-12-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth' magnetic field.

  6. PHYS: Division of Physical Chemistry 258 - Properties and Origins of Cometary and Asteroidal Organic Matter Delivered to the Early Earth

    Science.gov (United States)

    Messenger, Scott; Nguyen, Ann

    2017-01-01

    Comets and asteroids may have contributed much of the Earth's water and organic matter. The Earth accretes approximately 4x10(exp 7) Kg of dust and meteorites from these sources every year. The least altered meteorites contain complex assemblages of organic compounds and abundant hydrated minerals. These carbonaceous chondrite meteorites probably derive from asteroids that underwent hydrothermal processing within the first few million years after their accretion. Meteorite organics show isotopic and chemical signatures of low-T ion-molecule and grain-surface chemistry and photolysis of icy grains that occurred in cold molecular clouds and the outer protoplanetary disk. These signatures have been overprinted by aqueously mediated chemistry in asteroid parent bodies, forming amino acids and other prebiotic molecules. Comets are much richer in organic matter but it is less well characterized. Comet dust collected in the stratosphere shows larger H and N isotopic anomalies than most meteorites, suggesting better preservation of primordial organics. Rosetta studies of comet 67P coma dust find complex organic matter that may be related to the macromolecular material that dominates the organic inventory of primitive meteorites. The exogenous organic material accreting on Earth throughout its history is made up of thousands of molecular species formed in diverse processes ranging from circumstellar outflows to chemistry at near absolute zero in dark cloud cores and the formative environment within minor planets. NASA and JAXA are currently flying sample return missions to primitive, potentially organic-rich asteroids. The OSIRIS-REx and Hayabusa2 missions will map their target asteroids, Bennu and Ryugu, in detail and return regolith samples to Earth. Laboratory analyses of these pristine asteroid samples will provide unprecedented views of asteroidal organic matter relatively free of terrestrial contamination within well determined geological context. Studies of

  7. Widespread tungsten isotope anomalies and W mobility in crustal and mantle rocks of the Eoarchean Saglek Block, northern Labrador, Canada: Implications for early Earth processes and W recycling

    Science.gov (United States)

    Liu, Jingao; Touboul, Mathieu; Ishikawa, Akira; Walker, Richard J.; Graham Pearson, D.

    2016-08-01

    Well-resolved 182W isotope anomalies, relative to the present mantle, in Hadean-Archean terrestrial rocks have been interpreted to reflect the effects of variable late accretion and early mantle differentiation processes. To further explore these early Earth processes, we have carried out W concentration and isotopic measurements of Eoarchean ultramafic rocks, including lithospheric mantle rocks, meta-komatiites, a layered ultramafic body and associated crustal gneisses and amphibolites from the Uivak gneiss terrane of the Saglek Block, northern Labrador, Canada. These analyses are augmented by in situ W concentration measurements of individual phases in order to examine the major hosts of W in these rocks. Although the W budget in some rocks can be largely explained by a combination of their major phases, W in other rocks is hosted mainly in secondary grain-boundary assemblages, as well as in cryptic, unidentified W-bearing 'nugget' minerals. Whole rock W concentrations in the ultramafic rocks show unexpected enrichments relative, to elements with similar incompatibilities. By contrast, W concentrations are low in the Uivak gneisses. These data, along with the in situ W concentration data, suggest metamorphic transport/re-distribution of W from the regional felsic rocks, the Uivak gneiss precursors, to the spatially associated ultramafic rocks. All but one sample from the lithologically varied Eoarchean Saglek suite is characterized by generally uniform ∼ + 11 ppm enrichments in 182W relative to Earth's modern mantle. Modeling shows that the W isotopic enrichments in the ultramafic rocks were primarily inherited from the surrounding 182W-rich felsic precursor rocks, and that the W isotopic composition of the original ultramafic rocks cannot be determined. The observed W isotopic composition of mafic to ultramafic rocks in intimate contact with ancient crust should be viewed with caution in order to plate constraints on the early Hf-W isotopic evolution of the

  8. Early

    Directory of Open Access Journals (Sweden)

    Kamel Abd Elaziz Mohamed

    2014-04-01

    Conclusion: Early PDT is recommended for patients who require prolonged tracheal intubation in the ICU as outcomes like the duration of mechanical ventilation length of ICU stay and hospital stay were significantly shorter in early tracheostomy.

  9. Search for petrographic and geochemical evidence for the late heavy bombardment on earth in early archean rocks from Isua, Greenland

    Science.gov (United States)

    Koeberl, Christian; Reimold, Wolf Uwe; McDonald, Iain; Rosing, Minik

    The Moon was subjected to intense post-accretionary bombardment between about 4.5 and 3.9 billion years ago, and there is evidence for a short and intense late heavy bombardment period, around 3.85 ± 0.05 Ga. If a late heavy bombardment occurred on the Moon, the Earth must have been subjected to an impact flux at least as intense. The consequences for the Earth must have been devastating. In an attempt to investigate if any record of such a late heavy bombardment period on the Earth has been preserved, we performed a petrographic and geochemical study of some of the oldest rocks on Earth, from Isua in Greenland. We attempted to identify any remnant evidence of shock metamorphism in these rocks by petrographic studies, and used geochemical methods to detect the possible presence of an extraterrestrial component in these rocks. For the shock metamorphic study, we studied zircon, a highly refractive mineral that is resistant to alteration and metamorphism. Zircon crystals from old and eroded impact structures were found earlier to contain a range of shock-induced features at the optical and electron microscope level. Many of the studied zircon grains from Isua are strongly fractured, and single planar fractures do occur, but never as part of sets; none of the crystals studied shows any evidence of optically visible shock deformation. Several samples of Isua rocks were analyzed for their chemical composition, including the platinum group element (PGE) abundances, by neutron activation analysis and ICP-MS. Three samples showed somewhat elevated Ir contents (up to 0.2 ppb) compared to the detection limit, which is similar to the present-day crustal background content (0.03 ppb), but the chondrite-normalized siderophile element abundance patterns are non-chondritic, which could be a sign of either a small extraterrestrial component (if an indigenous component is subtracted), or terrestrial (re)mobilization mechanisms. In absence of any evidence for shock metamorphism

  10. Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.

    2012-01-01

    In this column, members of the NASP Crisis Management in the Schools Interest Group provide summaries of three studies relevant to school crisis response. The first study investigated the prevalence of posttraumatic stress disorder (PTSD) among rescue workers. The second article explored the Child and Family Traumatic Stress Intervention, which is…

  11. Mergeable summaries

    DEFF Research Database (Denmark)

    Agarwal, Pankaj K.; Graham, Graham; Huang, Zengfeng;

    2013-01-01

    of the datasets. But some other fundamental ones, like those for heavy hitters and quantiles, are not (known to be) mergeable. In this article, we demonstrate that these summaries are indeed mergeable or can be made mergeable after appropriate modifications. Specifically, we show that for ϵ-approximate heavy...

  12. Executive summary

    NARCIS (Netherlands)

    van Nimwegen, N.; van Nimwegen, N.; van der Erf, R.

    2009-01-01

    The Demography Monitor 2008 gives a concise overview of current demographic trends and related developments in education, the labour market and retirement for the European Union and some other countries. This executive summary highlights the major findings of the Demography Monitor 2008 and further

  13. Recognition of > or = 3850 Ma water-lain sediments in West Greenland and their significance for the early Archaean Earth

    Science.gov (United States)

    Nutman, A. P.; Mojzsis, S. J.; Friend, C. R.; Bada, J. L. (Principal Investigator)

    1997-01-01

    A layered body of amphibolite, banded iron formation (BIF), and ultramafic rocks from the island of Akilia, southern West Greenland, is cut by a quartz-dioritic sheet from which SHRIMP zircon 206Pb/207Pb weighted mean ages of 3865 +/- 11 Ma and 3840 +/- 8 Ma (2 sigma) can be calculated by different approaches. Three other methods of assessing the zircon data yield ages of >3830 Ma. The BIFs are interpreted as water-lain sediments, which with a minimum age of approximately 3850 Ma, are the oldest sediments yet documented. These rocks provide proof that by approximately 3850 Ma (1) there was a hydrosphere, supporting the chemical sedimentation of BIF, and that not all water was stored in hydrous minerals, and (2) that conditions satisfying the stability of liquid water imply surface temperatures were similar to present. Carbon isotope data of graphitic microdomains in apatite from the Akilia island BIF are consistent with a bio-organic origin (Mojzsis et al. 1996), extending the record of life on Earth to >3850 Ma. Life and surface water by approximately 3850 Ma provide constraints on either the energetics or termination of the late meteoritic bombardment event (suggested from the lunar cratering record) on Earth.

  14. Early Earth differentiation processes investigated through the short-lived 146Sm-142Nd and 182Hf-182W isotope systems

    Science.gov (United States)

    Rizo Garza, H. L.; Walker, R. J.; Carlson, R.; Touboul, M.; Horan, M. F.; Puchtel, I. S.; Boyet, M.; Rosing, M. T.

    2016-12-01

    The earliest history of Earth is difficult to capture due to the scarcity and high degrees of alteration of ancient terrains. Nevertheless, short-lived isotope systems can provide important constraints on early geological processes. The 182Hf-182W (t1/2 = 8.9 Ma) and 146Sm-142Nd (t1/2=103 Ma) systems are variably sensitive to differentiation processes that occurred during the first 50 Ma and 500 Ma of Earth's history, respectively. Eoarchean mantle-derived rocks from the Isua supracrustal belt (southwest Greenland) show well-resolved anomalies in both 182W (+5 to +21 ppm) and 142Nd (-10 to +15 ppm) compared to terrestrial standards. While there is evidence that W was mobilized in the crust accessed by the Isua suite, W and Nd isotopic anomalies are interpreted to primarily reflect Hadean processes that affected the mantle precursors of these rocks. Variations in 142Nd do not correlate with those of 182W, however, suggesting different mechanisms for the origin and retention of the isotopic anomalies present in these two systems. The 142Nd data, combined with 143Nd data for the long-lived 147Sm-143Nd system, are interpreted to reflect silicate crystal-liquid fractionation 4.3 Ga ago. Variations of 182W in the Isua lavas mantle source could also have been produced as a result of Hf/W fractionation caused by silicate differentiation during the lifetime of 182Hf, but these processes would have to somehow be decoupled from the processes that affected Sm/Nd. Alternatively, 182W variability could be the result of combined early Hf/W fractionations caused by metal-silicate segregation within discrete mantle domains and late accretion processes. Variations in 182W and 142Nd observed in the Isua supracrustal rocks are similar to those observed in the ancient rocks from Nuvvuagittuq Greenstone Belt, the Acasta Gneiss Complex, and the Saglek Block, suggesting that similar processes affected diverse early Earth rocks.

  15. Potential of Ozone Formation by the Smog Mechanism to shield the surface of the Early Earth from UV radiation?

    CERN Document Server

    Grenfell, J L; Patzer, B; Titz, R; Rauer, H; Grenfell, John Lee; Stracke, Barbara; Patzer, Beate; Titz, Ruth; Rauer, Heike

    2006-01-01

    We propose that the photochemical smog mechanism produced substantial ozone (O3) in the troposphere during the Proterozoic, which contributed to ultraviolet (UV) radiation shielding hence favoured the establishment of life. The smog mechanism is well-established and is associated with pollution hazes which sometimes cover modern cities. The mechanism proceeds via the oxidation of volatile organic compounds (VOCs) such as methane (CH4) in the presence of UV radiation and nitrogen oxides (NOx). It would have been particularly favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm) recently suggested. Proterozoic UV levels on the surface of the Earth were generally higher compared with today, which would also have favoured the mechanism. On the other hand, Proterozoic O2 required in the final step of the smog mechanism to form O3 was less abundant compared with present times. Further, results are sensitive to Proterozoic NOx concentrations, which are challenging to predict, since they depen...

  16. Microbial Paleontology, Mineralogy and Geochemistry of Modern and Ancient Thermal Spring Deposits and Their Recognition on the Early Earth and Mars"

    Science.gov (United States)

    Farmer, Jack D.

    2004-01-01

    The vision of this project was to improve our understanding of the processes by which microbiological information is captured and preserved in rapidly mineralizing sedimentary environments. Specifically, the research focused on the ways in which microbial mats and biofilms influence the sedimentology, geochemistry and paleontology of modem hydrothermal spring deposits in Yellowstone national Park and their ancient analogs. Toward that goal, we sought to understand how the preservation of fossil biosignatures is affected by 1) taphonomy- the natural degradation processes that affect an organism from the time of its death, until its discovery as a fossil and 2) diagenesis- longer-term, post-depositional processes, including cementation and matrix recrystallization, which collectively affect the mineral matrix that contains fossil biosignature information. Early objectives of this project included the development of observational frameworks (facies models) and methods (highly-integrated, interdisciplinary approaches) that could be used to explore for hydrothermal deposits in ancient terranes on Earth, and eventually on Mars.

  17. The Janus face of iron on anoxic worlds: iron oxides are both protective and destructive to life on the early Earth and present-day Mars.

    Science.gov (United States)

    Wadsworth, Jennifer; Cockell, Charles S

    2017-05-01

    The surface of the early Earth was probably subjected to a higher flux of ultraviolet (UV) radiation than today. UV radiation is known to severely damage DNA and other key molecules of life. Using a liquid culture and a rock analogue system, we investigated the interplay of protective and deleterious effects of iron oxides under UV radiation on the viability of the model organism, Bacillus subtilis. In the presence of hydrogen peroxide, there exists a fine balance between iron oxide's protective effects against this radiation and its deleterious effects caused by Photo-Fenton reactions. The maximum damage was caused by a concentration of hematite of ∼1 mg/mL. Concentrations above this confer increasing protection by physical blockage of the UV radiation, concentrations below this cause less effective UV radiation blockage, but also a correspondingly less effective Photo-Fenton reaction, providing an overall advantage. These results show that on anoxic worlds, surface habitability under a high UV flux leaves life precariously poised between the beneficial and deleterious effects of iron oxides. These results have relevance to the Archean Earth, but also the habitability of the Martian surface, where high levels of UV radiation in combination with iron oxides and hydrogen peroxide can be found. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth

    Directory of Open Access Journals (Sweden)

    Chaitanya V. Mungi

    2015-01-01

    Full Text Available Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in “prebiotic phosphodiester polymers” prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

  19. Characterization of RNA-Like Oligomers from Lipid-Assisted Nonenzymatic Synthesis: Implications for Origin of Informational Molecules on Early Earth.

    Science.gov (United States)

    Mungi, Chaitanya V; Rajamani, Sudha

    2015-01-05

    Prebiotic polymerization had to be a nonenzymatic, chemically driven process. These processes would have been particularly favored in scenarios which push reaction regimes far from equilibrium. Dehydration-rehydration (DH-RH) cycles are one such regime thought to have been prevalent on prebiotic Earth in niches like volcanic geothermal pools. The present study defines the optimum DH-RH reaction conditions for lipid-assisted polymerization of nucleotides. The resultant products were characterized to understand their chemical makeup. Primarily, our study demonstrates that the resultant RNA-like oligomers have abasic sites, which means these oligomers lack information-carrying capability because of losing most of their bases during the reaction process. This results from low pH and high temperature conditions, which, importantly, also allows the formation of sugar-phosphate oligomers when ribose 5'-monophosphates are used as the starting monomers instead. Formation of such oligomers would have permitted sampling of a large variety of bases on a preformed polymer backbone, resulting in "prebiotic phosphodiester polymers" prior to the emergence of modern RNA-like molecules. This suggests that primitive genetic polymers could have utilized bases that conferred greater N-glycosyl bond stability, a feature crucial for information propagation in low pH and high temperature regimes of early Earth.

  20. Chemo-dynamical deuterium fractionation in the early solar nebula: The origin of water on Earth and in asteroids and comets

    CERN Document Server

    Albertsson, T; Henning, Th

    2014-01-01

    Formation and evolution of water in the Solar System and the origin of water on Earth constitute one of the most interesting questions in astronomy. The prevailing hypothesis for the origin of water on Earth is by delivery through water-rich small Solar system bodies. In this paper, the isotopic and chemical evolution of water during the early history of the solar nebula, before the onset of planetesimal formation, is studied. A gas-grain chemical model that includes multiply-deuterated species and nuclear spin-states is combined with a steady-state solar nebula model. To calculate initial abundances, we simulated 1 Myr of evolution of a cold and dark TMC1-like prestellar core. Two time-dependent chemical models of the solar nebula are calculated over 1 Myr: (1) a laminar model and (2) a model with 2D turbulent mixing. We find that the radial outward increase of the H2O D/H ratio is shallower in the chemo-dynamical nebular model compared to the laminar model. This is related to more efficient de-fractionation...

  1. Lu Hf systematics of the ultra-high temperature Napier Metamorphic Complex in Antarctica: Evidence for the early Archean differentiation of Earth's mantle

    Science.gov (United States)

    Choi, Sung Hi; Mukasa, Samuel B.; Andronikov, Alexandre V.; Osanai, Yasuhito; Harley, Simon L.; Kelly, Nigel M.

    2006-06-01

    The Napier Complex of the East Antarctic Craton comprises some of the oldest rocks on Earth (˜ 3.8 billion years old), overprinted by an ultra-high temperature (UHT) metamorphic event near the Archean-Proterozoic boundary. Garnet, orthopyroxene, sapphirine, osumilite, rutile and a whole rock representing a fully equilibrated assemblage from this UHT granulite belt have yielded a Lu-Hf isochron age of 2403 ± 43 Ma, the first ever determined on a UHT mineral assemblage. Preservation of the UHT mineral assemblage in the rock analyzed, without any significant retrogression, suggests rapid cooling with closure likely to have occurred for the Lu-Hf system at post-peak UHT conditions near a temperature of ˜ 800 °C. This mineral-whole rock isochron yields an initial 176Hf/ 177Hf ratio corresponding to an ɛHf value of - 14 ± 1, acquired during UHT metamorphism. Such a low value demonstrates that overall UHT granulites evolved in a low Lu/Hf environment, probably formed when the rocks were first extracted from a highly depleted mantle. Zircon ɛHf values we have measured "see through" the UHT metamorphism and show that the source materials for the magmas that formed the Napier Complex were extremely depleted (> + 5.6 ɛHf at 3.85 Ga) relative to the chondritic uniform reservoir (CHUR). These results also suggest significant depletion of the early Archean mantle, in agreement with the early differentiation of the Earth that the latest core formation models require.

  2. Earth science: Extraordinary world

    Science.gov (United States)

    Day, James M. D.

    2016-09-01

    The isotopic compositions of objects that formed early in the evolution of the Solar System have been found to be similar to Earth's composition -- overturning notions of our planet's chemical distinctiveness. See Letters p.394 & p.399

  3. Leveraging Current Initiatives to Bring Earth and Space Science into Elementary and Early Childhood Classrooms: NGSS in the Context of the Classroom Technology Push

    Science.gov (United States)

    Pacheco-Guffrey, H. A.

    2016-12-01

    Classroom teachers face many challenges today such as new standards, the moving targets of high stakes tests and teacher evaluations, inconsistent/insufficient access to resources and evolving education policies. Science education in the K-5 context is even more complex. NGSS can be intimidating, especially to K-5 educators with little science background. High stakes science tests are slow to catch up with newly drafted state level science standards, leaving teachers unsure about what to change and when to implement updated standards. Amid all this change, many schools are also piloting new technology programs. Though exciting, tech initiatives can also be overwhelming to teachers who are already overburdened. A practical way to support teachers in science while remaining mindful of these stressors is to design and share resources that leverage other K-5 school initiatives. This is often done by integrating writing or math into science learning to meet Common Core requirements. This presentation will suggest a method for bringing Earth and space science learning into elementary / early childhood classrooms by utilizing the current push for tablet technology. The goal is to make science integration reasonable by linking it to technology programs that are in their early stages. The roles and uses of K-5 Earth and space science apps will be examined in this presentation. These apps will be linked to NGSS standards as well as to the science and engineering practices. To complement the app resources, two support frameworks will also be shared. They are designed to help educators consider new technologies in the context of their own classrooms and lessons. The SAMR Model (Puentadura, 2012) is a conceptual framework that helps teachers think critically about the means and purposes of integrating technology into existing lessons. A practical framework created by the author will also be shared. It is designed to help teachers identify and address the important logistical

  4. Pisolithus tinctorius, Fungal Extremophile and Modern Analog to an Early Earth Environment; An Unlikely Harbor for Deeply Diverging and Novel Chemoautrophic Microbes

    Science.gov (United States)

    Cullings, K. C.; Lauzon, C.; Marinkovich, N.; Truong, T.

    2014-12-01

    Endosymbioses have given rise to some of the most important innovations in Earth's history. Indeed, ecological facilitation has been pivotal to the creation of higher order complexity, and in driving evolutionary transitions at every level of organization from cellular organelles to multicellularity. In this study we address a newly discovered endosymbiosis between prokaryotes and a eukaryote growing with no apparent external energy source in soils associated with acid-sulfate hydrothermal springs. Hydrothermal sites are relevant to origin of life because they provide a chemical and energetic environment that may have provided energy for pre-biotic synthesis in the absence of photosynthesis through chemoautotrophy. Pisolithus (genus, picture 1 below) is a terrestrial fungal extremophile that can grow in thermally altered soils of acid-thermal hot springs at extreme low pH and elevated temperature, thriving in conditions that are beyond the threshold of survivability for most other organisms. Fruiting bodies of this fungus accumulate elemental sulfur into the spore producing tissues (gleba) of the fruiting body. The gleba is encased in a thick peridium, or shell. Further, Pisolithus is capable of enzymatic conversion of elemental S to sulfate. The fruiting bodies are rich in hydrocarbons, contain water through much of their development and are also likely to contain CO2 from fungal cellular respiration. Further, our data indicate the presence of anaerobic zones within. Thus, the internal environment of Pisolithus contains many conditions relevant to early Earth environments in which life is thought to have originated. We used 16S rDNA sequences to test the hypothesis that Pisolithus individuals contain novel and/or ancient microbial lineages. Our data reveal lineages comprised of novel relatives of known aerobic and anaerobic chemoautrophic Bacteria (85-90% BLAST search matches), several deeply divergent and novel Bacterial lineages, and a newly discovered lineage

  5. Profile summary.

    Science.gov (United States)

    2003-01-01

    All drugs appearing in the Adis Profile Summary table have been selected based on information contained in R&D Insight trade mark, a proprietary product of Adis International. The information in the profiles is gathered from the world's medical and scientific literature, at international conferences and symposia, and directly from the developing companies themselves. The emphasis of Drugs in R&D is on the clinical potential of new drugs, and selection of agents for inclusion is based on products in late-phase clinical development that have recently had a significant change in status.

  6. Summary guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Halsnaes, K.; Painuly, J.P.; Turkson, J.; Meyer, H.J.; Markandya, A.

    1999-09-01

    This document is a summary version of the methodological guidelines for climate change mitigation assessment developed as part of the Global Environment Facility (GEF) project Economics of Greenhouse Gas Limitations; Methodological Guidelines. The objectives of this project have been to develop a methodology, an implementing framework and a reporting system which countries can use in the construction of national climate change mitigation policies and in meeting their future reporting obligations under the FCCC. The methodological framework developed in the Methodological Guidelines covers key economic concepts, scenario building, modelling tools and common assumptions. It was used by several country studies included in the project. (au) 13 refs.

  7. Summary Lecture

    Indian Academy of Sciences (India)

    J. O. Stenflo

    2000-09-01

    This summary lecture makes no attempt to summarize what was actually said at the meeting, since this is well covered by the other contributors. Instead I have structured my presentation in three parts: First I try to demonstrate why the Sun is unique by comparing it with laboratory plasmas. This is followed by some personal reminiscences that go back a significant fraction of the century. I conclude in the form of a poem about this memorable conference in honor of the centennial anniversary of the Kodaikanal Observatory.

  8. Thunderstorm activity in early Earth: same estimations from point of view a role of electric discharges in formation of prebiotic conditions

    Science.gov (United States)

    Serozhkin, Yu.

    2008-09-01

    Introduction The structure and the physical parameters of an early Earth atmosphere [1], most likely, played a determining role in formation of conditions for origin of life. The estimation of thunderstorm activity in atmosphere of the early Earth is important for understanding of the real role of electrical discharges during formation of biochemical compounds. The terrestrial lightning a long time are considered as one of components determining a physical state and chemical structure of an atmosphere. Liebig in 1827 has considered a capability of nitrogen fixation at discharges of lightning [2]. Recent investigations (Lamarque et al. 1996) have achieved that production rate of NOx due to lightning at 3·106 ton/year [3]. The efficiency of electric discharges as energy source for synthesis of low molecular weight organic compounds is explained by the several factors. To them concern effect of optical radiation, high temperature, shock waves and that is especially important, pulse character of these effects. The impulse impact is essentially reduced the probability of destruction of the formed compounds. However, for some reasons is not clear the real role of electric discharges in synthesis of biochemical compounds. The discharges used in experiments on synthesis of organic substances, do not remind the discharges observable in a nature. One more aspect of a problem about a role of electric discharges in forming pre-biotic conditions on the Earth is connected with the thunderstorm activity in a modern atmosphere. This activity is connected with the presence in an atmosphere of ice crystals and existing gradient of temperature. To tell something about a degree of thunderstorm activity during the early Earth, i.e. that period, when formed pre-biotic conditions were is very difficult. Astrobiological potential of various discharges First of all the diversity of electric discharges in terrestrial atmosphere (usual lightning, lightning at eruption of volcanoes

  9. Evaluating the primary and/or diagenetic origin of rare earth element abundances in Ediacaran to early Cambrian phosphate deposits, Yangtze Platform (South China) by LA-ICPMS

    Science.gov (United States)

    Hippler, Dorothee; Klügel, Andreas; Biedermann, Nicole; Guo, Qingjun; Franz, Gerhard

    2014-05-01

    The Precambrian-Cambrian time interval represents one of the greatest phosphogenic episodes in Earth's history with giant and well-preserved phosphate deposits occurring on the Yangtze Platform in South China. We investigated concentrations of rare earth elements (REE) and yttrium of shallow and deep-water sedimentary phosphate deposits of the Ediacaran Doushantou Formation and the early Cambrian Zhongyicun Formation by using LA-ICP mass spectrometry. The aim is to examine the temporal and spatial variability of seawater chemistry in conjunction with the conditions of phosphate formation and the evaluation of the extent of diagenetic modification. The mineralogical and textural composition of the samples was pre-screened using SEM and XRD, and polished thick sections were prepared for subsequent high-resolution LA-ICPMS analyses. Overall concentrations in REE range between 18 and 657 ppm, with elevated concentrations (> 200 ppm) in apatite from the deep-water phosphate deposits. REE+Y patterns of shallow-water phosphate deposits exhibit the evolution from flat shale-like to gently inclined seawater-derived patterns, with the early Cambrian phosphate deposits revealing distinct negative Ce- and positive Y-anomalies indicative for oxygenated surface waters. REE+Y patterns of phosphate deposits of the deep-water facies are flat to highly enriched in MREE, which is manifested in variably pronounced concave-down patterns. In detail, these patterns display different Ce-anomalies, as well as small positive Eu-anomalies. We propose that REE+Y patterns of Ediacaran and early Cambrian sedimentary phosphate deposits can inherit both primary and secondary signatures reflecting either seawater composition or diagenetic modification and fluid flow. The combination of imaging techniques and in-situ LA-ICPMS thereby enables a more sophisticated examination of the potential sources and processes than whole rock determinations. Placing the results in stratigraphic order and assuming

  10. Early Earth differentiation investigated through 142Nd, 182W, and highly siderophile element abundances in samples from Isua, Greenland

    Science.gov (United States)

    Rizo, H.; Walker, R. J.; Carlson, R. W.; Touboul, M.; Horan, M. F.; Puchtel, I. S.; Boyet, M.; Rosing, M. T.

    2016-02-01

    We report new data for W concentrations, stable W isotopic compositions, high-precision 182W/184W ratios, highly siderophile element (HSE) abundances and 187Re-187Os systematics in a suite of 3.8-3.3 Ga mafic and ultramafic rocks from the Isua supracrustal belt, and the Paleoarchean terrane in the northwestern part of the belt. These data are compared with published data for 146Sm-142Nd systematics in the same samples. The samples from the Isua supracrustal belt show well resolved excesses of 182W/184W of up to ∼21 ppm, consistent with previous W isotopic data reported by Willbold et al. (2011). While there is abundant evidence that W was mobilized in the crust accessed by the Isua supracrustal suite, the isotopic anomalies are interpreted to primarily reflect processes that affected the mantle precursors to these rocks. The origin of the 182W excesses in these rocks remains uncertain. The Isua mantle source could represent a portion of the post-core-formation mantle that was isolated from late accretionary additions (e.g., Willbold et al., 2011). However, the combined 182W, Re-Os isotopic systematics and HSE abundances estimated for the source of the Isua basalts are difficult to reconcile with this interpretation. The W isotope variations were more likely produced as a result of fractionation of the Hf/W ratio in the mantle during the lifetime of 182Hf, i.e., during the first 50 Ma of Solar System history. This could have occurred as a result of differentiation in an early magma ocean. The Isua suite examined is also characterized by variable 142Nd/144Nd, but the variations do not correlate with the variations in 182W/184W. Further, samples with ages between 3.8 and 3.3 Ga show gradual diminution of 142Nd anomalies until these are no longer resolved from the modern mantle isotopic composition. By contrast, there is no diminishment of 182W variability with time, suggesting different mechanisms of origin and retention of isotopic variations for these two extinct

  11. The decline of the early Neolithic population center of 'Ain Ghazal and corresponding earth-surface processes, Jordan Rift Valley

    Science.gov (United States)

    Zielhofer, Christoph; Clare, Lee; Rollefson, Gary; Wächter, Stephan; Hoffmeister, Dirk; Bareth, Georg; Roettig, Christopher; Bullmann, Heike; Schneider, Birgit; Berke, Hubert; Weninger, Bernhard

    2012-11-01

    'Ain Ghazal is among the earliest large population centers known in the Middle East. A total of four major stratigraphic cultural units have been identified: 1) The oldest Middle Pre-Pottery Neolithic B (MPPNB) unit (10.2 to 9.5 cal ka BP) clearly corresponds with the early Holocene maximum Dead Sea levels. 2) The second unit consists of Late Pre-Pottery Neolithic B (LPPNB) in situ walls and hearths. 3) In the subsequent PPNC (8.9 to 8.6 cal ka BP) the population density at the settlement drops dramatically, which corresponds with a significant drop in the Dead Sea level. 4) The 4th stratigraphic unit is characterized by the "Yarmoukian rubble layer". Additionally, there is evidence for a previously unrecognized use of the site by Chalcolithic pastoralists. Sedimentological analyses reveal a constant increase in dust from a remote source during the entire human occupation period, which correlates well with the detectable drops in climatic humidity from the Dead Sea. As the major focus of this study, we can now rule out previous notions that the "Yarmoukian" rubble layer could have been produced by (catastrophic) slope-scale gravitational movements. To this point, it appears that the Neolithic mega-site was abandoned due to a climatic aridification.

  12. Improving the Quality of Early Intervention Personnel by Enhancing Faculty Expertise: Findings and Recommendations of the Regional Faculty Institutes. Executive Summary.

    Science.gov (United States)

    Hebbeler, Kathy, Ed.

    In 1992, the Office of Special Education Programs (OSEP) funded four projects for a three-year period to increase the participation of higher education faculty in inservice training for personnel in early intervention. These projects included: the Southeastern Institute for Faculty Training (SIFT), the Northeastern Early Intervention Faculty…

  13. Iron and oxygen isotope fractionation during iron UV photo-oxidation: Implications for early Earth and Mars

    Science.gov (United States)

    Nie, Nicole X.; Dauphas, Nicolas; Greenwood, Richard C.

    2017-01-01

    Banded iron formations (BIFs) contain appreciable amounts of ferric iron (Fe3+). The mechanism by which ferrous iron (Fe2+) was oxidized into Fe3+ in an atmosphere that was globally anoxic is highly debated. Of the three scenarios that have been proposed to explain BIF formation, photo-oxidation by UV photons is the only one that does not involve life (the other two are oxidation by O2 produced by photosynthesis, and anoxygenic photosynthesis whereby Fe2+ is directly used as electron donor in place of water). We experimentally investigated iron and oxygen isotope fractionation imparted by iron photo-oxidation at a pH of 7.3. The iron isotope fractionation between precipitated Fe3+-bearing lepidocrocite and dissolved Fe2+ follows a Rayleigh distillation with an instantaneous 56Fe/54Fe fractionation factor of + 1.2 ‰. Such enrichment in the heavy isotopes of iron is consistent with the values measured in BIFs. We also investigated the nature of the mass-fractionation law that governs iron isotope fractionation in the photo-oxidation experiments (i.e., the slope of the δ56Fe-δ57Fe relationship). The experimental run products follow a mass-dependent law corresponding to the high-T equilibrium limit. The fact that a ∼3.8 Gyr old BIF sample (IF-G) from Isua (Greenland) falls on the same fractionation line confirms that iron photo-oxidation in the surface layers of the oceans was a viable pathway to BIF formation in the Archean, when the atmosphere was largely transparent to UV photons. Our experiments allow us to estimate the quantum yield of the photo-oxidation process (∼0.07 iron atom oxidized per photon absorbed). This yield is used to model iron oxidation on early Mars. As the photo-oxidation proceeds, the aqueous medium becomes more acidic, which slows down the reaction by changing the speciation of iron to species that are less efficient at absorbing UV-photons. Iron photo-oxidation in centimeter to meter-deep water ponds would take months to years to

  14. Uderstanding Snowball Earth Deglaciation

    Science.gov (United States)

    Abbot, D. S.

    2012-12-01

    Earth, a normally clement planet comfortably in its star's habitable zone, suffered global or nearly global glaciation at least twice during the Neoproterozoic era (at about 635 and 710 million years ago). Viewed in the context of planetary evolution, these pan-global glaciations (Snowball Earth events) were extremely rapid, lasting only a few million years. The dramatic effect of the Snowball Earth events on the development of the planet can be seen through their link to rises in atmospheric oxygen and evolutionary innovations. These potential catastrophes on an otherwise clement planet can be used to gain insight into planetary habitability more generally. Since Earth is not currently a Snowball, a sound deglaciation mechanism is crucial for the viability of the Snowball Earth hypothesis. The traditional deglaciation mechanism is a massive build up of CO2 due to reduced weathering during Snowball Earth events until tropical surface temperatures reach the melting point. Once initiated, such a deglaciation might happen on a timescale of only dozens of thousands of years and would thrust Earth from the coldest climate in its history to the warmest. Therefore embedded in Snowball Earth events is an even more rapid and dramatic environmental change. Early global climate model simulations raised doubt about whether Snowball Earth deglaciation could be achieved at a CO2 concentration low enough to be consistent with geochemical data, which represented a potential challenge to the Snowball Earth hypothesis. Over the past few years dust and clouds have emerged as the essential missing additional processes that would allow Snowball Earth deglaciation at a low enough CO2 concentration. I will discuss the dust and cloud mechanisms and the modeling behind these ideas. This effort is critical for the broader implications of Snowball Earth events because understanding the specific deglaciation mechanism determines whether similar processes could happen on other planets.

  15. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  16. Oxygen isotope perspective on crustal evolution on early Earth: A record of Precambrian shales with emphasis on Paleoproterozoic glaciations and Great Oxygenation Event

    Science.gov (United States)

    Bindeman, I. N.; Bekker, A.; Zakharov, D. O.

    2016-03-01

    We present stable isotope and chemical data for 206 Precambrian bulk shale and tillite samples that were collected mostly from drillholes on all continents and span the age range from 0.5 to 3.5 Ga with a dense coverage for 2.5-2.2 Ga time interval when Earth experienced four Snowball Earth glaciations and the irreversible rise in atmospheric O2. We observe significant, downward shift of several ‰ and a smaller range of δ18 O values (7 to 9‰) in shales that are associated with the Paleoproterozoic and, potentially, Neoproterozoic glaciations. The Paleoproterozoic samples consist of more than 50% mica minerals and have equal or higher chemical index of alteration than overlying and underlying formations and thus underwent equal or greater degrees of chemical weathering. Their pervasively low δ18 O and δD (down to - 85 ‰) values provide strong evidence of alteration and diagenesis in contact with ultra-low δ18 O glacial meltwaters in lacustrine, deltaic or periglacial lake (sikussak-type) environments associated with the Paleoproterozoic glaciations. The δDsilicate values for the rest of Precambrian shales range from -75 to - 50 ‰ and are comparable to those for Phanerozoic and Archean shales. Likewise, these samples have similar ranges in δ13Corg values (-23 to - 33 ‰ PDB) and Corg content (0.0 to 10 wt%) to Phanerozoic shales. Precambrian shales have a large range of δ18 O values comparable to that of the Phanerozoic shales in each age group and formation, suggesting similar variability in the provenance and intensity of chemical weathering, except for the earliest 3.3-3.5 Ga Archean shales, which have consistently lower δ18 O values. Moreover, Paleoproterozoic shales that bracket in age the Great Oxidation Event (GOE) overlap in δ18 O values. Absence of a step-wise increase in δ18 O and δD values suggests that despite the first-order change in the composition of the atmosphere, weathering cycle was not dramatically affected by the GOE at ∼2

  17. Bear Creek Valley Floodplain hot spot removal early action characterization field data summary report, Oak Ridge Y-12 Plant, Oak Ridge, Tennessee

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This report summarizes the field and laboratory efforts as a result of the Bear Creek Floodplain Hot Spot Removal Project Early Action. The purpose of this project was to collect data necessary to assess contaminant levels in the Bear Creek Valley Floodplain and evaluate the risk posed by the sites. This report provides information on the background of the site, characterization of site and field activities, results of field and laboratory data collected, extent and distribution of contamination, and an assessment of the future risk posed by the site.

  18. Engaging the Geodetic and Geoscience Communities in EarthScope Education and Outreach

    Science.gov (United States)

    Charlevoix, D. J.; Berg, M.; Morris, A. R.; Olds, S. E.

    2013-12-01

    UNAVCO is NSF's geodetic facility and operates as a university-governed consortium dedicated to facilitating geoscience research and education, including the support of EarthScope. The Education and Community Engagement program at UNAVCO provides support for broader impacts both externally to the broader University and EarthScope community as well as internally to the UNAVCO. During the first 10 years of EarthScope UNAVCO has engaged in outreach and education activities across the EarthScope footprint ranging from outreach to formal and informal educators and interpreters, to technical training for university faculty and researchers. UNAVCO works jointly with the EarthScope National Office and IRIS while simultaneously maintaining and developing an independent engagement and education program. UNAVCO provides training in the form of technical short courses to researchers including graduate students and early-career professionals, and conducts educational workshops for K-12 educators. A suite of educational materials focused on the integration of EarthScope data into curriculum materials is available from UNAVCO and will soon expand the undergraduate offerings to include a broader suite of geodesy applications activities for undergraduate students. UNAVCO provides outreach materials and in support of EarthScope including summaries of research project and campaign highlights, science snapshots featuring summaries of scientific advancements made possible by UNAVCO services and non-technical communications via social media. UNAVCO also provides undergraduate students exposure to EarthScope science research participation in a year-long research internship managed by UNAVCO (Research Experiences in Solid Earth Science for Students - RESESS).

  19. Geological constraints on detecting the earliest life on Earth: a perspective from the Early Archaean (older than 3.7 Gyr) of southwest Greenland

    OpenAIRE

    Fedo, Christopher M; Whitehouse, Martin J.; Kamber, Balz S.

    2006-01-01

    At greater than 3.7 Gyr, Earth's oldest known supracrustal rocks, comprised dominantly of mafic igneous with less common sedimentary units including banded iron formation (BIF), are exposed in southwest Greenland. Regionally, they were intruded by younger tonalites, and then both were intensely dynamothermally metamorphosed to granulite facies (the highest pressures and temperatures generally encountered in the Earth's crust during metamorphism) in the Archaean and subsequently at lower grade...

  20. Summary of the Workshop"Power and Belief in Early Civilizations"%"'早期文明中的权力与信仰'学术沙龙"纪要

    Institute of Scientific and Technical Information of China (English)

    北京大学考古文博学院

    2015-01-01

    The workshop of Power and Belief in Early Civilizations was held at the School of Archaeolo-gy and Museology, Peking University, on June 13, 2015. It was one of the academic activities of"Power in Things:New Perspectives on Liangzhu", the special exhibition of the Arthur M. Sackler Museum of Art and Archaeology, Peking University. More than 20 scholars from different academic and research institutions in China attended the workshop and conducted discussions on the following topics:new archaeological discov-eries of Liangzhu Archaeological Sites and Liangzhu Culture;the nature and operating mechanism of the Li-angzhu society; the relations between Liangzhu Culture and the other archaeological cultures; theories and methods adopted in studying the origins and early stages of Chinese civilization. Taking a social studies per-spective, the workshop tried to describe archaeological material heritage by borrowing concepts and ideas from historical and political studies. The exhibition itself also adopted a sociology and history perspective in exhibiting the material culture of archaeology with a reflection of the progress and development of the archae-ology discipline.%2015年6月13日,北京大学赛克勒考古与艺术博物馆"权力与信仰——良渚遗址群考古特展"系列学术活动之一的"'早期文明中的权力与信仰'学术沙龙"在北京大学考古文博学院举行,国内多家学术机构的20余位学者围绕良渚遗址及良渚文化的考古新发现、良渚社会的性质与运行机制、良渚文化与其他考古学文化的关系、中国文明起源和早期发展的理论与方法等议题展开讨论.本次沙龙尝试从研究社会的角度,用历史学、政治学语言描述考古学物质文化遗存;而展览亦尝试运用社会学和历史学的视角对考古学物质文化进行展示,体现了考古学学科的前进和发展.

  1. NASA Strategic Roadmap Summary Report

    Science.gov (United States)

    Wilson, Scott; Bauer, Frank; Stetson, Doug; Robey, Judee; Smith, Eric P.; Capps, Rich; Gould, Dana; Tanner, Mike; Guerra, Lisa; Johnston, Gordon

    2005-01-01

    In response to the Vision, NASA commissioned strategic and capability roadmap teams to develop the pathways for turning the Vision into a reality. The strategic roadmaps were derived from the Vision for Space Exploration and the Aldrich Commission Report dated June 2004. NASA identified 12 strategic areas for roadmapping. The Agency added a thirteenth area on nuclear systems because the topic affects the entire program portfolio. To ensure long-term public visibility and engagement, NASA established a committee for each of the 13 areas. These committees - made up of prominent members of the scientific and aerospace industry communities and senior government personnel - worked under the Federal Advisory Committee Act. A committee was formed for each of the following program areas: 1) Robotic and Human Lunar Exploration; 2) Robotic and Human Exploration of Mars; 3) Solar System Exploration; 4) Search for Earth-Like Planets; 5) Exploration Transportation System; 6) International Space Station; 7) Space Shuttle; 8) Universe Exploration; 9) Earth Science and Applications from Space; 10) Sun-Solar System Connection; 11) Aeronautical Technologies; 12) Education; 13) Nuclear Systems. This document contains roadmap summaries for 10 of these 13 program areas; The International Space Station, Space Shuttle, and Education are excluded. The completed roadmaps for the following committees: Robotic and Human Exploration of Mars; Solar System Exploration; Search for Earth-Like Planets; Universe Exploration; Earth Science and Applications from Space; Sun-Solar System Connection are collected in a separate Strategic Roadmaps volume. This document contains memebership rosters and charters for all 13 committees.

  2. Unique post-doctoral positions in Master of Arts in Teaching Earth Science program at the American Museum of Natural History: Involving early-career research scientists in Earth science education

    Science.gov (United States)

    Flores, K. E.; Nadeau, P. A.; Zirakparvar, N. A.; Grcevich, J.; Ustunisik, G. K.

    2012-12-01

    Post-doctoral positions in Earth science fields traditionally emphasize research within a university setting or research institute. Such positions may include a teaching component, but one which is often restricted to introductory undergraduate Earth science courses or upper-level courses within their own field of specialization. With such a specific focus, there may not be much inclination on the part of a post-doctoral fellow to involve themselves in broader education programs, such as public outreach or secondary schools. The American Museum of Natural History is now conducting a non-traditional post-doctoral position as part of its new Master of Arts in Teaching Earth Science (MAT). This pilot program involves forging a one-of-a-kind partnership between a world-class research museum and high-needs schools in New York City with the goal of addressing a critical shortage of qualified Earth Science teachers in New York State, particularly in high-needs schools with diverse populations. The program, which is part of the state's Race to the Top initiative, is approved by the NYS Board of Regents and will prepare a total of 50 candidates in two cohorts to earn a Board of Regents-awarded Masters of Arts in Teaching (MAT) degree with a specialization in Earth Science for grades 7-12. The post-doctoral fellows of the MAT program have unique 3-year positions, with more traditional research-based work comprising 65% of the tenure and non-traditional educational roles 35%. The MAT fellows are divided into two types: those with a teaching role, who are involved in the co-design and co-teaching of graduate-level Earth science courses; and those in a research/mentoring role, who design and teach a summer-long science research practicum while also providing informal support to MAT teaching candidates throughout the school year. Over the first year of the MAT program's implementation, fellows have been exposed to a range of activities outside the realm of a traditional post

  3. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  4. Summary the race to reinvent energy and stop global warming

    CERN Document Server

    2013-01-01

    Complete summary of Fred Krupp and Miriam Horn's book: ""Earth: The Sequel: The Race to Reinvent Energy and Stop Global Warming"". This summary of the ideas from Fred Krupp and Miriam Horn's book ""Earth: The Sequel"" explains how capitalism, as the most powerful economic force in the world, is the only engine of change that has the strength to stop global warming. In their book, the authors demonstrate how this can be achieved by installing a cap-and-trade initiative, providing genuine economic incentives for companies and reducing their carbon footprint. This summary explains their theory in

  5. Reactions between olivine and CO2-rich seawater at 300 °C: Implications for H2 generation and CO2 sequestration on the early Earth

    Directory of Open Access Journals (Sweden)

    Hisahiro Ueda

    2017-03-01

    Full Text Available To understand the influence of fluid CO2 on ultramafic rock-hosted seafloor hydrothermal systems on the early Earth, we monitored the reaction between San Carlos olivine and a CO2-rich NaCl fluid at 300 °C and 500 bars. During the experiments, the total carbonic acid concentration (ΣCO2 in the fluid decreased from approximately 65 to 9 mmol/kg. Carbonate minerals, magnesite, and subordinate amount of dolomite were formed via the water-rock interaction. The H2 concentration in the fluid reached approximately 39 mmol/kg within 2736 h, which is relatively lower than the concentration generated by the reaction between olivine and a CO2-free NaCl solution at the same temperature. As seen in previous hydrothermal experiments using komatiite, ferrous iron incorporation into Mg-bearing carbonate minerals likely limited iron oxidation in the fluids and the resulting H2 generation during the olivine alteration. Considering carbonate mineralogy over the temperature range of natural hydrothermal fields, H2 generation is likely suppressed at temperatures below approximately 300 °C due to the formation of the Mg-bearing carbonates. Nevertheless, H2 concentration in fluid at 300 °C could be still high due to the temperature dependency of magnetite stability in ultramafic systems. Moreover, the Mg-bearing carbonates may play a key role in the ocean-atmosphere system on the early Earth. Recent studies suggest that the subduction of carbonated ultramafic rocks may transport surface CO2 species into the deep mantle. This process may have reduced the huge initial amount of CO2 on the surface of the early Earth. Our approximate calculations demonstrate that the subduction of the Mg-bearing carbonates formed in komatiite likely played a crucial role as one of the CO2 carriers from the surface to the deep mantle, even in hot subduction zones.

  6. Summaries of FY 1994 geosciences research

    Energy Technology Data Exchange (ETDEWEB)

    1994-12-01

    The Geosciences Research Program is directed by the Department of Energy`s (DOE`s) Office of Energy Research (OER) through its Office of Basic Energy Sciences (OBES). Activities in the Geosciences Research Program are directed toward the long-term fundamental knowledge of the processes that transport, modify, concentrate, and emplace (1) the energy and mineral resources of the earth and (2) the energy byproducts of man. The Program is divided into five broad categories: Geophysics and earth dynamics; Geochemistry; Energy resource recognition, evaluation, and utilization; Hydrogeology and exogeochemistry; and Solar-terrestrial interactions. The summaries in this document, prepared by the investigators, describe the scope of the individual programs in these main areas and their subdivisions including earth dynamics, properties of earth materials, rock mechanics, underground imaging, rock-fluid interactions, continental scientific drilling, geochemical transport, solar/atmospheric physics, and modeling, with emphasis on the interdisciplinary areas.

  7. "The Only 13-Year-Old on Planet Earth without a Cell Phone": Meanings of Cell Phones in Early Adolescents' Everyday Lives

    Science.gov (United States)

    Blair, Bethany L.; Fletcher, Anne C.

    2011-01-01

    Cellular telephones have become an increasingly prevalent feature of contemporary American life, with usage often beginning during early adolescence. With this in mind, twenty 7th graders and their mothers participated in separate qualitative interviews regarding early adolescents' use of cell phones as well as perceived risks and benefits of such…

  8. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  9. Budget Summary of Changes

    Data.gov (United States)

    Pension Benefit Guaranty Corporation — The Summary of Changes dataset extracted from PBGC's congressional budget justification. It contains all administrative and program increases and decreases including...

  10. FEMA Disaster Declarations Summary

    Data.gov (United States)

    Department of Homeland Security — The FEMA Disaster Declarations Summary is a summarized dataset describing all federally declared disasters, starting with the first disaster declaration in 1953,...

  11. Molecular catalysis of rare-earth elements

    Energy Technology Data Exchange (ETDEWEB)

    Roesky, Peter W. (ed.) [Karlsruhe Institute of Technology (KIT) (Germany). Inst. of Inorganic Chemistry

    2010-07-01

    This volume reviews the recent developments in the use of molecular rare-earth metal compounds in catalysis. Most of the applications deal with homogenous catalysis but in some cases, heterogeneous systems are also mentioned. The rare-earth elements, which are the lanthanides and their close relatives - scandium and yttrium - have not been in the focus of molecular chemistry for a long time and therefore have also not been considered as homogenous catalysts. Although the first organometallic compounds of the lanthanides, which are tris(cyclopentadienyl) lanthanide complexes, were already prepared in the 1950s, it was only in the late 1970s and early 1980s when a number of research groups began to focus on this class of compounds. One reason for the development was the availability of single crystal X-ray diffraction techniques, which made it possible to characterize these compounds.Moreover, new laboratory techniques to handle highly air and moisture sensitive compounds were developed at the same time. Concomitant with the accessibility of this new class of compounds, the application in homogenous catalysis was investigated. One of the first applications in this field was the use of lanthanide metallocenes for the catalytic polymerization of ethylene in the early 1980s. In the last two or three decades, a huge number of inorganic and organometallic compounds of the rare-earth elements were synthesized and some of them were also used as catalysts. Although early work in homogenous catalysis basically focused only on the hydrogenation and polymerization of olefins, the scope for catalytic application today is much broader. Thus, a large number of catalytic {sigma}-bond metathesis reactions, e.g. hydroamination, have been reported in the recent years. This book contains four chapters in which part of the recent development of the use of molecular rare-earth metal compounds in catalysis is covered. To keep the book within the given page limit, not all aspects could be

  12. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  13. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  14. Earth Sciences Division annual report 1989

    Energy Technology Data Exchange (ETDEWEB)

    1990-06-01

    This Annual Report presents summaries of selected representative research activities from Lawrence Berkeley Laboratory grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrology, Geology and Geochemistry, and Geophysics and Geomechanics. We are proud to be able to bring you this report, which we hope will convey not only a description of the Division's scientific activities but also a sense of the enthusiasm and excitement present today in the Earth Sciences.

  15. Biofuels: Project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1994-07-01

    The US DOE, through the Biofuels Systems Division (BSD) is addressing the issues surrounding US vulnerability to petroleum supply. The BSD goal is to develop technologies that are competitive with fossil fuels, in both cost and environmental performance, by the end of the decade. This document contains summaries of ongoing research sponsored by the DOE BSD. A summary sheet is presented for each project funded or in existence during FY 1993. Each summary sheet contains and account of project funding, objectives, accomplishments and current status, and significant publications.

  16. Summary big data

    CERN Document Server

    2014-01-01

    This work offers a summary of Cukier the book: "Big Data: A Revolution That Will Transform How we Live, Work, and Think" by Viktor Mayer-Schonberg and Kenneth. Summary of the ideas in Viktor Mayer-Schonberg's and Kenneth Cukier's book: " Big Data " explains that big data is where we use huge quantities of data to make better predictions based on the fact we identify patters in the data rather than trying to understand the underlying causes in more detail. This summary highlights that big data will be a source of new economic value and innovation in the future. Moreover, it shows that it will

  17. Evolution of U fractionation processes through geologic time : consequences for the variation of U deposit types from Early Earth to Present

    Science.gov (United States)

    Cuney, M.

    2009-12-01

    U deposits are known at nearly all stages of the geological cycle, but are not known prior to 2.95 Ga. Also, U deposit types vary greatly from Mesoarchean to Present. Most of these changes through time can be attributed to major modifications in the geodynamic evolution of the Earth, in magmatic fractionation processes, in the composition of the Atmosphere and in the nature of life. The first U-rich granites able to crystallize uraninite, appeared at about 3.1 Ga. They correspond to the most fractionated terms of high-K calcalkaline suites, resulting from crystal fractionation of magmas possibly derived from melting of mantle wedges enriched in K, U, Th. Highly fractionated peraluminous leucogranites, able to crystallize uraninite, appeared at about 2.6 Ga. Erosion of these two granite types led to the detrital accumulation of uraninite that formed the first U deposits on Earth: the Quartz Pebble Conglomerates from 2.95 to 2.4 Ga. From 2.3 Ga onwards, uprise of oxygen level in the atmosphere led to the oxidation of U(IV) to U(VI), U transport in solution, and exuberant development of marine algae in epicontinental platform sediments. From 2.3 to 1.8 Ga large amounts of U, previously accumulated as U(IV) minerals, were dissolved and trapped preferentially in passive margin settings, in organic-rich sediments, and which led to the formation of the world’s largest Paleoproterozoic U provinces, e.g. : the Wollaston belt, Canada and the Cahill Formation, Australia. During and after the worldwide 2.1-1.75 Ga orogenic events, responsible for the formation of the Nuna supercontinent, U trapped in these formations was the source for several types of mineralization: (i) metamorphosed U-mineralized graphitic schists, calcsilicates and meta-arkoses, (ii) diagenetic-hydrothermal remobilization with the formation of the first deposits related to redox processes at 2.0 Ga (Oklo, Gabon), (iii) partial melting of U-rich metasediments forming the uraninite disseminations in

  18. Use of Molecular Fossils for the Interpretation of Paleoenvironments on Early Earth: The Synthesis of Lipid Biomarkers by Methane-Oxidizing Bacteria

    Science.gov (United States)

    Jahnke, Linda L.; Summons, Roger E.; Chang, Sherwood (Technical Monitor)

    1994-01-01

    Over the course of Earth's history, the most important biological influence has come from the evolution of oxygenic photosynthesis and the development of an oxygen-rich biosphere. Although the availability of free oxygen had profound effects on subsequent biological and planetary evolution, clear paleobiological evidence of the timing of this transition is lacking. Recent technical advances in the microanalysis of organic matter has made it possible to detect residual molecules (biomarkers) in proterozoic (2.5 to 0.6 billion years) sedimentary rock characteristic of specific groups of microorganisms. When coupled with the carbon isotopic fractionations characteristic of biological systems and the new field of compound specific isotope analysis, biomarkers could prove to be a powerful tool for decoding ancient biochemistry from the geological record. We have been studying the carbon isotope fractionations associated with the synthesis of organic biomarker molecules in several types of methane-oxidizing bacteria that should have been key to carbon cycling in paleoenvironments after the evolution of oxygenic photosynthesis.

  19. The HADES RV Programme with HARPS-N@TNG - GJ 3998: An early M-dwarf hosting a system of Super-Earths

    CERN Document Server

    Affer, L; Damasso, M; Perger, M; Ribas, I; Mascareño, A Suárez; Hernández, J I González; Rebolo, R; Poretti, E; Maldonado, J; Leto, G; Pagano, I; Scandariato, G; Sanchez, R Zanmar; Sozzetti, A; Bonomo, A S; Malavolta, L; Morales, J C; Rosich, A; Bignamini, A; Gratton, R; Velasco, S; Cenadelli, D; Claudi, R; Cosentino, R; Desidera, S; Giacobbe, P; Herrero, E; Lafarga, M; Lanza, A F; Molinari, E; Piotto, G

    2016-01-01

    Context. M dwarfs are considered ideal targets for Doppler radial velocity searches. Nonetheless, the statistics of frequency of low-mass planets hosted by low mass stars remains poorly constrained. Aims. Our M-dwarf radial velocity monitoring with HARPS-N can provide a major contribution to the widening of the current statistics through the in-depth analysis of accurate radial velocity observations in a narrow range of spectral sub-types (79 stars, between dM0 to dM3). Spectral accuracy will enable us to reach the precision needed to detect small planets with a few earth masses. Our survey will bring a contribute to the surveys devoted to the search for planets around M-dwarfs, mainly focused on the M-dwarf population of the northern emisphere, for which we will provide an estimate of the planet occurence. Methods. We present here a long duration radial velocity monitoring of the M1 dwarf star GJ 3998 with HARPS-N to identify periodic signals in the data. Almost simultaneous photometric observations were car...

  20. MSIS State Summary Datamarts

    Data.gov (United States)

    U.S. Department of Health & Human Services — This page provides background needed to take advantage of the capabilities of the MSIS State Summary Datamart. This mart allows the user to develop high-level...

  1. Annual Meteorological Summaries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Single-year summaries of observations at Weather Bureau and cooperative stations across the United States. Predominantly the single page Form 1066, which includes...

  2. Oceanographic Monthly Summary

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Oceanographic Monthly Summary contains sea surface temperature (SST) analyses on both regional and ocean basin scales for the Atlantic, Pacific, and Indian Oceans....

  3. Global Climate Summaries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Global Hourly Summaries are simple indicators of observational normals which include climatic data summarizations and frequency distributions. These typically...

  4. Heat-pipe Earth.

    Science.gov (United States)

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

  5. Summary of blog

    CERN Document Server

    Reader, Capitol

    2013-01-01

    This ebook consists of a summary of the ideas, viewpoints and facts presented by Hugh Hewitt in his book "Blog: Understanding the Information Reformation that's Changing Your World". This summary offers a concise overview of the entire book in less than 30 minutes reading time. However this work does not replace in any case Hugh Hewitt's book.Hewitt argues that blogs have an important potential and he believes that it would be a dreadful mistake to avoid their power.

  6. Preliminary reference Earth model

    Science.gov (United States)

    Dziewonski, Adam M.; Anderson, Don L.

    1981-06-01

    A large data set consisting of about 1000 normal mode periods, 500 summary travel time observations, 100 normal mode Q values, mass and moment of inertia have been inverted to obtain the radial distribution of elastic properties, Q values and density in the Earth's interior. The data set was supplemented with a special study of 12 years of ISC phase data which yielded an additional 1.75 × 10 6 travel time observations for P and S waves. In order to obtain satisfactory agreement with the entire data set we were required to take into account anelastic dispersion. The introduction of transverse isotropy into the outer 220 km of the mantle was required in order to satisfy the shorter period fundamental toroidal and spheroidal modes. This anisotropy also improved the fit of the larger data set. The horizontal and vertical velocities in the upper mantle differ by 2-4%, both for P and S waves. The mantle below 220 km is not required to be anisotropic. Mantle Rayleigh waves are surprisingly sensitive to compressional velocity in the upper mantle. High S n velocities, low P n velocities and a pronounced low-velocity zone are features of most global inversion models that are suppressed when anisotropy is allowed for in the inversion. The Preliminary Reference Earth Model, PREM, and auxiliary tables showing fits to the data are presented.

  7. Nd isotope composition and rare earth element distribution in early Paleozoic biogenic apatite from Baltoscandia: A signature of Iapetus ocean water

    Science.gov (United States)

    Felitsyn, Sergei; Sturesson, Ulf; Popov, Leonid; Holmer, Lars

    1998-12-01

    Analyses of the Nd isotopic composition and REE distribution in biogenic apatite (organophosphatic brachiopods and conodont elements) from the Cambrian and Ordovician sequences of the Baltic plate give new insights into the development of the southeastern segment of the continental margin bounding the Iapetus ocean. The Nd isotope analyses show ɛNd(t) of ˜-8.0 for the Cambrian, indicating that the main source of the sedimentary deposition came from weathered sedimentary rocks of Vendian and Cambrian age. The increase of ɛNd(t) to ˜-5.0 for the Early Ordovician indicates the appearance of a new source of radiogenic Nd in the surrounding area—most likely a volcanic arc along the western borderland of Baltic plate from Arenigian time. Samples of Cambrian biogenic apatite show significantly lower total amounts of REE than do the Ordovician samples, and this is probably due to a shorter exposure to seawater before burial during Ordovician sedimentary accumulation in Baltoscandia. These preliminary results suggest that biogenic apatite from the Baltoscandian basin preserves geochemical signatures of the water masses that will be important for understanding the evolution of the Iapetus ocean during the early Paleozoic.

  8. Deformation-aided segregation of Fe-S liquid from olivine under deep Earth conditions: Implications for core formation in the early solar system

    Science.gov (United States)

    Berg, Madeleine T. L.; Bromiley, Geoffrey D.; Butler, Ian B.; Frost, Mungo; Bradley, Robert; Carr, James; Le Godec, Yann; Montési, Laurent G. J.; Zhu, Wenlu; Miller, Kevin; Perrillat, Jean-Philippe; Mariani, Elisabetta; Tatham, Daniel; Redfern, Simon A. T.

    2017-02-01

    The planets and larger rocky bodies of the inner solar system are differentiated, and consist of metallic, iron-rich cores surrounded by thick shells of silicate. Core formation in these bodies, i.e. the segregation of metal from silicate, was a key process in the early solar system, and one which left a lasting geochemical signature. It is commonly assumed that extensive silicate melting and formation of deep magma oceans was required to initiate core formation, due to the inability of iron-rich melts to segregate from a solid silicate matrix. Here we assess the role of deformation in aiding segregation of core-forming melts from solid silicate under conditions of planetary deep interiors. Low-strain rate, high-pressure/temperature deformation experiments and high-resolution 2-D and 3-D textural analysis demonstrate that deformation fundamentally alters iron-rich melt geometry, promoting wetting of silicate grain boundaries and formation of extensive micron to sub-micron width Fe-rich melt bands. Deformation-aided Fe-S melt networks noted here contrast those observed in higher finite strain experiments conducted at lower pressure, and may reveal either an alternative mechanism for melt segregation at higher pressures, or an early stage process of melt segregation. Results suggest, however, that core-mantle chemical equilibration cannot be assumed in models of planetary formation, and that instead, the chemistry of rocky planets may record a complex, multi-stage process of core formation.

  9. The Hades RV Programme With Harps-N@TNG GJ 3998: An Early M-Dwarf Hosting a System of Super-Earths

    Science.gov (United States)

    Affer, Laura; Micela, Giuseppina; Damasso, Mario; Perger, Manuel; Ribas, Ignasi; Suárez Mascareño, Alejandro; González Hernández, Jonay Isai; Rebolo, Rafael; Poretti, Ennio; Maldonado, Jesus; Leto, Giuseppe; Pagano, Isabella; Scandariato, Gaetano; Zanmar Sanchez, Ricardo; Sozzetti, Alessandro; Bonomo, Aldo Stefano; Malavolta, Luca; Morales, Juan Carlos; Rosich, Albert; Bignamini, Andrea; Gratton, Raffaele; Velasco, Sergio; Cenadelli, Davide; Claudi, Riccardo; Cosentino, Rosario; Desidera, Silvano; Giacobbe, Paolo; Herrero, Enrique; Lafarga, Marina; Lanza, Antonino Francesco; Molinari, Emilio; Piotto, Giampaolo

    2016-07-01

    Many efforts to detect Earth-like planets around low-mass stars are presently devoted in almost every extra-solar planetsearch. M dwarfs are considered ideal targets for Doppler radial velocity searches because their low masses and luminosities makelow-mass planets orbiting in their habitable zones more easily detectable than those around higher mass stars. Nonetheless, thestatistics of frequency of low-mass planets hosted by low mass stars remains poorly constrained.Our M-dwarf radial velocity monitoring with HARPS-N within the GAPS (Global architectures of Planetary Systems) - ICE(Institut de Ciències de l'Espai CSIC-IEEC) - IAC (Instituto de Astrofísica de Canarias) projectcan provide a major contributionto the widening of the current statistics through the in-depth analysis of accurate radial velocity observations in a narrow range ofspectral sub-types (79 stars, between dM0 to dM3). Spectral accuracy will enable us to reach the precision needed to detect smallplanets with a few earth masses. Our survey will bring a contribute to the surveys devoted to the search for planets around M-dwarfs, mainly focused on the M-dwarf population of the northern emisphere, for which we will provide an estimate of the planet occurrence.We present here a long duration radial velocity monitoring of theM1 dwarf star GJ 3998 with HARPS-N to identify periodicsignals in the data. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programs tocharacterize the stellar activity and to distinguish from the periodic signals those due to activity and to the presence of planetarycompanions. We run an MCMC simulation and use Bayesian model selection to determine the number of planets in this system, toestimate their orbital parameters and minimum masses and for a proper treatment of the activity noise.The radial velocities have a dispersion in excess of their internal errors due to at least four superimposed signals, with periodsof 30.7, 13.7, 42

  10. HADES RV program with HARPS-N at the TNG GJ 3998: An early M-dwarf hosting a system of super-Earths

    Science.gov (United States)

    Affer, L.; Micela, G.; Damasso, M.; Perger, M.; Ribas, I.; Suárez Mascareño, A.; González Hernández, J. I.; Rebolo, R.; Poretti, E.; Maldonado, J.; Leto, G.; Pagano, I.; Scandariato, G.; Zanmar Sanchez, R.; Sozzetti, A.; Bonomo, A. S.; Malavolta, L.; Morales, J. C.; Rosich, A.; Bignamini, A.; Gratton, R.; Velasco, S.; Cenadelli, D.; Claudi, R.; Cosentino, R.; Desidera, S.; Giacobbe, P.; Herrero, E.; Lafarga, M.; Lanza, A. F.; Molinari, E.; Piotto, G.

    2016-10-01

    Context. Many efforts are currently made to detect Earth-like planets around low-mass stars in almost every extra-solar planet search. M dwarfs are considered ideal targets for Doppler radial velocity searches because their low masses and luminosities make low-mass planets orbiting in these stars' habitable zones more easily detectable than those around higher mass stars. Nonetheless, the frequency statistics of low-mass planets hosted by low-mass stars remains poorly constrained. Aims: Our M-dwarf radial velocity monitoring with HARPS-N within the collaboration between the Global architectures of Planetary Systems (GAPS) project, the Institut de Ciències de l'Espai/CSIC-IEEC (ICE) and the Instituto de Astrofísica de Canarias (IAC) can provide a major contribution to the widening of the current statistics through the in-depth analysis of accurate radial velocity observations in a narrow range of spectral sub-types (79 stars, between dM0 to dM3). Spectral accuracy will enable us to reach the precision needed to detect small planets with a few Earth masses. Our survey will contribute to the surveys devoted to the search for planets around M-dwarfs, mainly focused on the M-dwarf population of the northern emisphere, for which we will provide an estimate of the planet occurrence. Methods: We present here a long-duration radial velocity monitoring of the M1 dwarf star GJ 3998 with HARPS-N to identify periodic signals in the data. Almost simultaneous photometric observations were carried out within the APACHE and EXORAP programs to characterize the stellar activity and to distinguish those due to activity and to the presence of planetary companions from the periodic signals. We ran a Markov chain Monte Carlo simulation and used a Bayesian model selection to determine the number of planets in this system, to estimate their orbital parameters and minimum mass, and to properly treat the activity noise. Results: The radial velocities have a dispersion in excess of their

  11. Mega-Impacts on Mars: Implications for the Late Heavy Bombardment in the Inner Solar System, and the Early Evolution of the Earth and Mars

    Science.gov (United States)

    Frey, Herbert

    2012-01-01

    There are about 30 very large impact basins on Mars, > 1000 km in diameter, most of which are revealed by their topographic and/or crustal thickness signatures. Crater retention ages and model absolute ages suggest these all formed in a relatively short time (100-200 million years?), perhaps during a "Late Heavy Bombardment" (LHB) caused by the evolution of the orbits of the giant planets. This so-called "Nice Model" of planetary formation may explain the LHB on the Moon at about 3.9 billion years ago and would have produced a similar bombardment throughout the inner solar system. The formation of 30 very large impact basins would have had catastrophic environmental consequences for Mars, which were further complicated by the demise of the global magnetic field at about the same time. If there are no very large basins on Mars older than the 30 we see and the LHB really lasted everywhere only a short time, there may have been a relatively longer time (400 million years?) during which Mars and the Earth suffered no major impact trauma and during which conditions on both worlds may have been far more habitable than during the LHB. However, if the formation of the Mars crustal dichotomy was due to an even larger giant impact that predated the very large basins, all record of this earlier and possibly more clement time on Mars may have been erased. Ages of the smaller but still very large basins can be used to approximately date the giant impact (if it occurred). Even the very large basins appear to have reset the crater retention ages of the entire crust of Mars and may have by themselves erased any record of an earlier time.

  12. The EarthScope Plate Boundary Observatory and allied networks, the makings of nascent Earthquake and Tsunami Early Warning System in Western North America.

    Science.gov (United States)

    Mattioli, Glen; Mencin, David; Hodgkinson, Kathleen; Meertens, Charles; Phillips, David; Blume, Fredrick; Berglund, Henry; Fox, Otina; Feaux, Karl

    2016-04-01

    The NSF-funded GAGE Facility, managed by UNAVCO, operates approximately ~1300 GNSS stations distributed across North and Central America and in the circum-Caribbean. Following community input starting in 2011 from several workshops and associated reports,UNAVCO has been exploring ways to increase the capability and utility of the geodetic resources under its management to improve our understanding in diverse areas of geophysics including properties of seismic, volcanic, magmatic and tsunami deformation sources. Networks operated by UNAVCO for the NSF have the potential to profoundly transform our ability to rapidly characterize events, provide rapid characterization and warning, as well as improve hazard mitigation and response. Specific applications currently under development include earthquake early warning, tsunami early warning, and tropospheric modeling with university, commercial, non-profit and government partners on national and international scales. In the case of tsunami early warning, for example, an RT-GNSS network can provide multiple inputs in an operational system starting with rapid assessment of earthquake sources and associated deformation, which leads to the initial model of ocean forcing and tsunami generation. In addition, terrestrial GNSScan provide direct measurements of the tsunami through the associated traveling ionospheric disturbance from several 100's of km away as they approach the shoreline,which can be used to refine tsunami inundation models. Any operational system like this has multiple communities that rely on a pan-Pacific real-time open data set. Other scientific and operational applications for high-rate GPS include glacier and ice sheet motions, tropospheric modeling, and better constraints on the dynamics of space weather. Combining existing data sets and user communities, for example seismic data and tide gauge observations, with GNSS and Met data products has proven complicated because of issues related to metadata

  13. Japanese Rare Earth Market

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Since China cancelled export rebate in May this year,prices of magnetic materials related rare earth productscontinuously rose. Increasing production cost is largelyattributed to investment in environmental protectionequipments. Prices of Nd and Dy metals rose 20~30% over thebeginning of this year.Price of Nd was USD 11.5 - 12/Kg from USD 9/Kg at theend of 2004, up 30%. Price of Dy rose to USD 65- 70/Kg fromUSD 50/Kg early this year, up 20%. Price of Pr climbed to USD13.5 - 14/Kg from USD 11/Kg, up 30%. Pri...

  14. Recreation Centers in the Daily Leisure of the Population of Central Non-Black Earth Region Countryside, Mid 1950s – Early 1960s

    Directory of Open Access Journals (Sweden)

    Kometchikov Igor

    2014-12-01

    Full Text Available In the mid 1950s – early 1960s the authorities make the effort to overcome material and technological underdevelopment of rural clubs in Central Nechernozemye and to increase the effectiveness of organization of the daily leisure of population by these institutions. In opposition to the departmental structure of the cultural and educational resources, the emphasis is made on the formation of the net of typical public rural clubs, which was combined with the main links of the enlarged collective farm production; on the rise of outer budget financing and the development of public initiative in the process of club functioning. However, under the circumstances of economic weakness of the most part of collective farms in Central Nechernozemye, the reforms lead not to interdepartmental model of solving the problems of the village culture and the enlargement of the range of club leisure, but to the replacement of its complicated verbal forms by the uniformity of cinema, radio and television broadcasts, and as a result to the strengthening of the authorities control over rural clubs. Their potential as of versatile village leisure centres is vanishing day by day, and is replaced by both family leisure and social deviations.

  15. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  16. Implications of a 3.472-3.333 Gyr-old subaerial microbial mat from the Barberton greenstone belt, South Africa for the UV environmental conditions on the early Earth.

    Science.gov (United States)

    Westall, Frances; de Ronde, Cornel E J; Southam, Gordon; Grassineau, Nathalie; Colas, Maggy; Cockell, Charles; Lammer, Helmut

    2006-10-29

    Modelling suggests that the UV radiation environment of the early Earth, with DNA weighted irradiances of about three orders of magnitude greater than those at present, was hostile to life forms at the surface, unless they lived in specific protected habitats. However, we present empirical evidence that challenges this commonly held view. We describe a well-developed microbial mat that formed on the surface of volcanic littoral sediments in an evaporitic environment in a 3.5-3.3Ga-old formation from the Barberton greenstone belt. Using a multiscale, multidisciplinary approach designed to strongly test the biogenicity of potential microbial structures, we show that the mat was constructed under flowing water by 0.25 microm filaments that produced copious quantities of extracellular polymeric substances, representing probably anoxygenic photosynthesizers. Associated with the mat is a small colony of rods-vibroids that probably represent sulphur-reducing bacteria. An embedded suite of evaporite minerals and desiccation cracks in the surface of the mat demonstrates that it was periodically exposed to the air in an evaporitic environment. We conclude that DNA-damaging UV radiation fluxes at the surface of the Earth at this period must either have been low (absorbed by CO2, H2O, a thin organic haze from photo-dissociated CH4, or SO2 from volcanic outgassing; scattered by volcanic, and periodically, meteorite dust, as well as by the upper layers of the microbial mat) and/or that the micro-organisms exhibited efficient gene repair/survival strategies.

  17. National Land Imaging Requirements (NLIR) Pilot Project summary report: summary of moderate resolution imaging user requirements

    Science.gov (United States)

    Vadnais, Carolyn; Stensaas, Gregory

    2014-01-01

    Under the National Land Imaging Requirements (NLIR) Project, the U.S. Geological Survey (USGS) is developing a functional capability to obtain, characterize, manage, maintain and prioritize all Earth observing (EO) land remote sensing user requirements. The goal is a better understanding of community needs that can be supported with land remote sensing resources, and a means to match needs with appropriate solutions in an effective and efficient way. The NLIR Project is composed of two components. The first component is focused on the development of the Earth Observation Requirements Evaluation System (EORES) to capture, store and analyze user requirements, whereas, the second component is the mechanism and processes to elicit and document the user requirements that will populate the EORES. To develop the second component, the requirements elicitation methodology was exercised and refined through a pilot project conducted from June to September 2013. The pilot project focused specifically on applications and user requirements for moderate resolution imagery (5–120 meter resolution) as the test case for requirements development. The purpose of this summary report is to provide a high-level overview of the requirements elicitation process that was exercised through the pilot project and an early analysis of the moderate resolution imaging user requirements acquired to date to support ongoing USGS sustainable land imaging study needs. The pilot project engaged a limited set of Federal Government users from the operational and research communities and therefore the information captured represents only a subset of all land imaging user requirements. However, based on a comparison of results, trends, and analysis, the pilot captured a strong baseline of typical applications areas and user needs for moderate resolution imagery. Because these results are preliminary and represent only a sample of users and application areas, the information from this report should only

  18. MIV Project: Executive Summary

    DEFF Research Database (Denmark)

    Ravazzotti, Mariolina T.; Jørgensen, John Leif; Neefs, Marc

    1997-01-01

    Under the ESA contract #11453/95/NL/JG(SC), aiming at assessing the feasibility of Rendez-vous and docking of unmanned spacecrafts, a reference mission scenario was defined. This report gives an executive summary of the achievements and results from the project.......Under the ESA contract #11453/95/NL/JG(SC), aiming at assessing the feasibility of Rendez-vous and docking of unmanned spacecrafts, a reference mission scenario was defined. This report gives an executive summary of the achievements and results from the project....

  19. Summaries of physical research in the geosciences

    Energy Technology Data Exchange (ETDEWEB)

    1981-10-01

    The Department of Energy supports research in the geosciences in order to provide a sound foundation of fundamental knowledge in those areas of earth, atmospheric, and solar-terrestrial sciences that are germane to the Department of Energy's many missions. The summaries describe the scope of the individual programs and detail the research performed during 1980 to 1981. The Geosciences Research Program includes research in geology, petrology, geophysics, geochemistry, hydrology, solar-terrestrial relationships, aeronomy, seismology, and natural resource analysis, including the various subdivisions and interdisciplinary areas.

  20. Summaries of physical research in the geosciences

    Energy Technology Data Exchange (ETDEWEB)

    1983-09-01

    The Department of Energy supports research in the geosciences in order to provide a sound foundation of fundamental knowledge in those areas of earth, atmospheric, and solar-terrestrial sciences that are germane to the Department of Energy's many missions. The summaries in the document describe the scope of the individual programs and detail the research performed during 1982 to 1983. The Geoscience Research Program includes research in geology, petrology, geophysics, geochemistry, hydrology, solar-terrestrial relationships, aeronomy, seismology, and natural resource analysis, including the various subdivisions and interdisciplinary areas. All such research is related either directly or indirectly to the Department of Energy's technological needs.

  1. Summaries of FY 1993 geosciences research

    Energy Technology Data Exchange (ETDEWEB)

    1993-12-01

    The Department of Energy supports research in the geosciences in order to provide a sound foundation of fundamental knowledge in those areas of the geosciences that are germane to the DOE`s many missions. The Geosciences Research Program is supported by the Office of Energy Research. The participants in this program include DOE laboratories, academic institutions, and other governmental agencies. These activities are formalized by a contract or grant between the DOE and the organization performing the work, providing funds for salaries, equipment, research materials, and overhead. The summaries in this document, prepared by the investigators, describe the scope of the individual programs. The Geosciences Research Program includes research in geophysics, geochemistry, resource evaluation, solar-terrestrial interactions, and their subdivisions including earth dynamics, properties of earth materials, rock mechanics, underground imaging, rock-fluid interactions, continental scientific drilling, geochemical transport, solar-atmospheric physics, and modeling, with emphasis on the interdisciplinary areas.

  2. Geothermal energy. Program summary

    Energy Technology Data Exchange (ETDEWEB)

    1979-06-01

    Brief descriptions of geothermal projects funded through the Department of Energy during FY 1978 are presented. Each summary gives the project title, contractor name, contract number, funding level, dates, location, and name of the principal investigator, together with project highlights, which provide informaion such as objectives, strategies, and a brief project description. (MHR)

  3. Nucleon Spin: Summary

    OpenAIRE

    Close, Frank

    1995-01-01

    This talk summarises the discussions during the conference on the spin structure of the nucleon held at Erice; July 1995. The summary focuses on where we have come, where we are now, and the emerging questions that direct where we go next in the quest to understand the nucleon spin.

  4. Crisis Management: Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.; Dorman, Sally; Anderson, Luke; McNair, Daniel

    2013-01-01

    This article presents summaries of three studies relevant to school crisis response. The first report, "A Framework for International Crisis Intervention" (Sally Dorman), is a review of how existing crisis intervention models (including the NASP PREPaRE model) have been adapted for international use. The second article, "Responding…

  5. Summary of Research 2002

    Science.gov (United States)

    2005-01-01

    the quality and quantity of sleep in U.S. Navy recruits. An examination of the activity level ( actigraphy ) data will show how much sleep recruits...25 Research Summaries Generative Decision Support Architecture Project...35 Monterey Security Enhanced Architecture Project ................................................................................. 36 Project

  6. Crisis Management: Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.; Dorman, Sally; Anderson, Luke; McNair, Daniel

    2013-01-01

    This article presents summaries of three studies relevant to school crisis response. The first report, "A Framework for International Crisis Intervention" (Sally Dorman), is a review of how existing crisis intervention models (including the NASP PREPaRE model) have been adapted for international use. The second article, "Responding…

  7. Executive Summaries: CIL '90.

    Science.gov (United States)

    Elsweiler, John A., Jr.; And Others

    1990-01-01

    Presents summaries of 12 papers presented at the 1990 Computers in Libraries Conference. Topics discussed include online searching; microcomputer-based serials management; microcomputer-based workstations; online public access catalogs (OPACs); multitype library networking; CD-ROM searches; locally mounted online databases; collection evaluation;…

  8. Healthcare. Executive Summary

    Science.gov (United States)

    Carnevale, Anthony P.; Smith, Nicole; Gulish, Artem; Beach, Bennett H.

    2012-01-01

    This executive summary highlights several findings about healthcare. These are: (1) Healthcare is 18 percent of the U.S. economy, twice as high as in other countries; (2) There are two labor markets in healthcare: high-skill, high-wage professional and technical jobs and low-skill, low-wage support jobs; (3) Demand for postsecondary education in…

  9. Biogeochemistry: Early phosphorus redigested

    Science.gov (United States)

    Poulton, Simon W.

    2017-02-01

    Atmospheric oxygen was maintained at low levels throughout huge swathes of Earth's early history. Estimates of phosphorus availability through time suggest that scavenging from anoxic, iron-rich oceans stabilized this low-oxygen world.

  10. Reversals of the Earth's Magnetic Field

    Science.gov (United States)

    Champion, Duene E.

    J.A. Jacobs of Cambridge University has written a concise, authoritative, and up-todate text on reversals of the earth's magnetic field. Chapter 1 is a concise summary of the basic attributes of the geomagnetic field and its behavior in different time frames. It explains spherical harmonic analysis of the field and presents the history of acquisition of the data that best represent the recent field. Lastly, it includes a short summary of the origin and electrodynamics of the magnetic field, outlining the current theoretical basis for its generation.

  11. Palomares Summary Report

    Science.gov (United States)

    1975-01-15

    disarmament conference was in progress in Geneva. The Soviet representative took advantage of the accident stating that, "only a fortunate stroke of luck saved...is particu- larly fitting that this summary of the Palomares accident , one of many specific instances of Dr. Langham’s valuable assistance to the ooD...be dedicated to his memory. We do so in fond appreciati.on. 3 THIS PAGE IS INTENTIONALLY LEFf BLANK 4 FOREWORD The accident which occurred over

  12. Blois V: Experimental summary

    Energy Technology Data Exchange (ETDEWEB)

    Albrow, M.G.

    1993-09-01

    The author gives a summary talk of the best experimental data given at the Vth Blois Workshop on Elastic and Diffractive Scattering. He addresses the following eight areas in his talk: total and elastic cross sections; single diffractive excitation; electron-proton scattering; di-jets and rapidity gaps; areas of future study; spins and asymmetries; high-transverse momentum and masses at the Tevatron; and disoriented chiral condensates and cosmic radiation.

  13. Unit 5. Thermodynamics (Summary)

    OpenAIRE

    Beléndez Vázquez, Augusto

    2012-01-01

    Summary of the "Unit 5. Thermodynamics" of course "Physical Foundations of Engineering I". Degree in Sound and Image Engineering, in Telecommunications. Polytechnic School of the University of Alicante Resumen del "Tema 5. Termodinámica" de la asignatura "Fundamentos Físicos de la Ingeniería I". Grado en Ingeniería en Sonido e Imagen en Telecomunicaciones. Escuela Politécnica Superior. Universidad de Alicante.

  14. ULSGEN (Uplink Summary Generator)

    Science.gov (United States)

    Wang, Y.-F.; Schrock, M.; Reeve, T.; Nguyen, K.; Smith, B.

    2014-01-01

    Uplink is an important part of spacecraft operations. Ensuring the accuracy of uplink content is essential to mission success. Before commands are radiated to the spacecraft, the command and sequence must be reviewed and verified by various teams. In most cases, this process requires collecting the command data, reviewing the data during a command conference meeting, and providing physical signatures by designated members of various teams to signify approval of the data. If commands or sequences are disapproved for some reason, the whole process must be restarted. Recording data and decision history is important for traceability reasons. Given that many steps and people are involved in this process, an easily accessible software tool for managing the process is vital to reducing human error which could result in uplinking incorrect data to the spacecraft. An uplink summary generator called ULSGEN was developed to assist this uplink content approval process. ULSGEN generates a web-based summary of uplink file content and provides an online review process. Spacecraft operations personnel view this summary as a final check before actual radiation of the uplink data. .

  15. Summary and synthesis

    Science.gov (United States)

    V. Alaric Sample; Christopher Topik

    2014-01-01

    America’s forests are undergoing changes unlike any seen before in human history. The concept of the Anthropocene Era, a new geologic epoch characterized by anthropogenic dominance over the Earth’s systems, has become an important framework for thinking about the processes and consequences of worldwide environmental change, particularly global climate change,...

  16. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  17. Regression Verification Using Impact Summaries

    Science.gov (United States)

    Backes, John; Person, Suzette J.; Rungta, Neha; Thachuk, Oksana

    2013-01-01

    Regression verification techniques are used to prove equivalence of syntactically similar programs. Checking equivalence of large programs, however, can be computationally expensive. Existing regression verification techniques rely on abstraction and decomposition techniques to reduce the computational effort of checking equivalence of the entire program. These techniques are sound but not complete. In this work, we propose a novel approach to improve scalability of regression verification by classifying the program behaviors generated during symbolic execution as either impacted or unimpacted. Our technique uses a combination of static analysis and symbolic execution to generate summaries of impacted program behaviors. The impact summaries are then checked for equivalence using an o-the-shelf decision procedure. We prove that our approach is both sound and complete for sequential programs, with respect to the depth bound of symbolic execution. Our evaluation on a set of sequential C artifacts shows that reducing the size of the summaries can help reduce the cost of software equivalence checking. Various reduction, abstraction, and compositional techniques have been developed to help scale software verification techniques to industrial-sized systems. Although such techniques have greatly increased the size and complexity of systems that can be checked, analysis of large software systems remains costly. Regression analysis techniques, e.g., regression testing [16], regression model checking [22], and regression verification [19], restrict the scope of the analysis by leveraging the differences between program versions. These techniques are based on the idea that if code is checked early in development, then subsequent versions can be checked against a prior (checked) version, leveraging the results of the previous analysis to reduce analysis cost of the current version. Regression verification addresses the problem of proving equivalence of closely related program

  18. Active Near Earth Asteroids

    Science.gov (United States)

    Jenniskens, Peter

    2015-08-01

    Past activity from Near Earth Asteroids is recorded in the meteoroid streams that cause our meteor showers. Automated meteoroid orbit surveys by photographic, low-light video, specular radar, and head-echo radar reflections are providing the first maps of meteor shower activity at different particle sizes. There are distinct differences in particle size distributions among streams. The underlaying mechanisms that created these streams are illuminated: fragmentation from spin-up or thermal stresses, meteoroid ejection by water vapor drag, and ejection of icy particles by CO and CO2 sublimation. The distribution of the meteoroid orbital elements probe the subsequent evolution by planetary perturbations and sample the range of dynamical processes to which Near Earth Asteroids are exposed. The non-stream "sporadic" meteors probe early stages in the evolution from meteoroid streams into the zodiacal dust cloud. We see that the lifetime of large meteoroids is generally not limited by collisions. Results obtained by the CAMS video survey of meteoroid orbits are compared to those from other orbit surveys. Since October 2010, over 200,000 meteoroid orbits have been measured. First results from an expansion into the southern hemisphere are also presented, as are first results from the measurement of main element compositions. Among the many streams detected so far, the Geminid and Sextantid showers stand out by having a relatively high particle density and derive from parent bodies that appear to have originated in the main belt.

  19. Copernicus Earth observation programme

    Science.gov (United States)

    Žlebir, Silvo

    European Earth observation program Copernicus is an EU-wide programme that integrates satellite data, in-situ data and modeling to provide user-focused information services to support policymakers, researchers, businesses and citizens. Land monitoring service and Emergency service are fully operational already, Atmosphere monitoring service and Marine environment monitoring service are preoperational and will become fully operational in the following year, while Climate change service and Security service are in an earlier development phase. New series of a number of dedicated satellite missions will be launched in the following years, operated by the European Space Agency and EUMETSAT, starting with Sentinel 1A satellite early this year. Ground based, air-borne and sea-borne in-situ data are provided by different international networks and organizations, EU member states networks etc. European Union is devoting a particular attention to secure a sustainable long-term operational provision of the services. Copernicus is also stated as a European Union’s most important contribution to Global Earth Observation System of Systems (GEOSS). The status and the recent development of the Copernicus programme will be presented, together with its future perspective. As Copernicus services have already demonstrated their usability and effectiveness, some interesting cases of their deployment will be presented. Copernicus free and open data policy, supported by a recently adopted EU legislative act, will also be presented.

  20. Heuristic Algorithm for Dynamic Task Planning of Early Warning System of Low Earth Orbit%低轨预警系统动态任务规划启发式算法

    Institute of Scientific and Technical Information of China (English)

    简平; 邹鹏; 熊伟

    2013-01-01

    该文针对低轨预警系统任务动态规划需求,从预警传感器资源和导弹跟踪任务角度对低轨预警系统动态任务规划问题进行了形式化描述,建立了系统动态任务规划的动态约束满足问题模型。该模型包括两级优化目标跟踪精度、资源利用率、传感器切换率、松弛度综合优化指标和方案调整幅度(调整率)指标;提出了求解动态规划问题的变邻域启发式搜索算法,设计了算法的直接插入、重新分配、替换和删除邻域结构及算子。通过仿真实验验证了基于梯度优化目标的动态规划模型的合理性,并说明启发式算法能有效求解低轨预警系统动态任务规划问题。%The dynamic task planning issue of early warning system of Low Earth Orbit (LEO) is described by the system resource and missile tracking task aspects, and the Dynamic Constraint Satisfaction Problem (DCSP) model of system dynamic task planning is built which includes two level index the integrative optimizing indexes of tracking precision, task accomplishment, sensor switching and resource slack, the adjusting range of original task planning scheme. To solve the dynamic planning model, a variable neighborhood heuristic algorithm on the basis of original planning and schedule is put forward, and the directly insert, redistribute, replace and delete neighborhood structure and their operators are designed in the heuristic algorithm. The simulation results show the leveled dynamic planning model is rational and the heuristic algorithm can solve the dynamic task planning issue of early warning system of LEO effectively.

  1. Earth Sciences Division annual report 1980

    Energy Technology Data Exchange (ETDEWEB)

    1981-07-01

    Summaries of the highlights of programs in the Earth Sciences Division are presented under four headings; Geosciences, Geothermal Energy Development, Nuclear Waste Isolation, and Marine Sciences. Utilizing both basic and applied research in a wide spectrum of topics, these programs are providing results that will be of value in helping to secure the nation's energy future. Separate abstracts have been prepared for each project for inclusion in the Energy Data Base. (DMC)

  2. FY 1996 activity summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-04-01

    The US Department of Energy Office of Nuclear and Facility Safety provides nuclear safety policy, independent technical evaluation, and technical support. A summary of these activities is provided in this report. These include: (1) changing the mission of the former production facilities to storage and waste management; (2) stabilizing nuclear materials not recycled due to production cessation or interruptions; (3) reformulating the authorization basis for existing facilities to convert to a standards based approach for operations consistent with modern expectations; and (4) implementing a modern regulatory framework for nuclear facilities. Enforcement of the Price-Anderson Amendments Act is also reported.

  3. Earth from Above

    Science.gov (United States)

    Stahley, Tom

    2006-01-01

    Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

  4. Intern Summary Reports

    Science.gov (United States)

    2004-01-01

    Topics covered include: Probe Station Antenna Range; LERCIP 2004 Summary; L.E.R.C.I.P. Internship Summary; Hubble Space Telescope Bi-Stem Thermal Shield Analyses; GRABER - the Duct Tape of Space and JIMO Heat Conducting Foam; CDF and PDF Comparison Between Humacao, Puerto Rico and Florida; Development of the On-board Aircraft Network; Development of the Planar Inlet Design and Analysis Process (PINDAP); An Overview of My 2004 Summer Internship [Non-destructive Evaluation]; My Summer Experience as an Administrative Officer Assistant [in the Safety and Assurance Directorate Office]; Programming an Experiment Control System; Reducing the Cation Exchange Capacity of Lithium Clay to Form Better Dispersed; Polymer-Clay Nanocomposites; Feasibility of EB Welded Hastelloy X and Combination of Refractory Metals; My Work in the NASA Glenn History Office and Records Management Office; Education, Technology, and Media: A Peak into My Summer Internship at NASA Glenn Research Center in Cleveland, Ohio; [The Engineering and Technical Services Directorate at the Glenn Research Center]; Drinking Water Database; Design of an EXB Probe; and Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen.

  5. The origin of volatiles in the Earth's mantle

    Science.gov (United States)

    Hier-Majumder, Saswata; Hirschmann, Marc M.

    2017-08-01

    The Earth's deep interior contains significant reservoirs of volatiles such as H, C, and N. Due to the incompatible nature of these volatile species, it has been difficult to reconcile their storage in the residual mantle immediately following crystallization of the terrestrial magma ocean (MO). As the magma ocean freezes, it is commonly assumed that very small amounts of melt are retained in the residual mantle, limiting the trapped volatile concentration in the primordial mantle. In this article, we show that inefficient melt drainage out of the freezing front can retain large amounts of volatiles hosted in the trapped melt in the residual mantle while creating a thick early atmosphere. Using a two-phase flow model, we demonstrate that compaction within the moving freezing front is inefficient over time scales characteristic of magma ocean solidification. We employ a scaling relation between the trapped melt fraction, the rate of compaction, and the rate of freezing in our magma ocean evolution model. For cosmochemically plausible fractions of volatiles delivered during the later stages of accretion, our calculations suggest that up to 77% of total H2O and 12% of CO2 could have been trapped in the mantle during magma ocean crystallization. The assumption of a constant trapped melt fraction underestimates the mass of volatiles in the residual mantle by more than an order of magnitude.Plain Language SummaryThe Earth's deep interior contains substantial amounts of volatile elements like C, H, and N. How these elements got sequestered in the Earth's interior has long been a topic of debate. It is generally assumed that most of these elements escaped the interior of the Earth during the first few hundred thousand years to create a primitive atmosphere, leaving the mantle reservoir nearly empty. In this work, we show that the key to this paradox involves the very early stages of crystallization of the mantle from a global magma ocean. Using numerical models, we show

  6. 1976 annual summary report

    Energy Technology Data Exchange (ETDEWEB)

    1978-03-01

    Abstracts of papers published during the previous calendar year, arranged in accordance with the project titles used in the USDOE Schedule 189 Budget Proposals, are presented. The collection of abstracts supplements the listing of papers published in the Schedule 189. The following subject areas are represented: high-energy physics; nuclear physics; basic energy sciences (nuclear science, materials sciences, solid state physics, materials chemistry); molecular, mathematical, and earth sciences (fundamental interactions, processes and techniques, mathematical and computer sciences); environmental research and development; physical and technological studies (characterization, measurement and monitoring); and nuclear research and applications.

  7. Hydrous parental magmas of Early to Middle Permian gabbroic intrusions in western Inner Mongolia, North China: New constraints on deep-Earth fluid cycling in the Central Asian Orogenic Belt

    Science.gov (United States)

    Pang, Chong-Jin; Wang, Xuan-Ce; Xu, Bei; Luo, Zhi-Wen; Liu, Yi-Zhi

    2017-08-01

    The role of fluids in the formation of the Permian-aged Xigedan and Mandula gabbroic intrusions in western Inner Mongolia was significant to the evolution of the Xing'an Mongolia Orogenic Belt (XMOB), and the active northern margin of the North China Craton (NCC). Secondary Ion Mass Spectroscopy (SIMS) U-Pb zircon geochronology establishes that the Xigedan gabbroic intrusion in the northern NCC was emplaced at 266 Ma, and is therefore slightly younger than the ca 280 Ma Mandula gabbroic intrusion in the XMOB. Along with their felsic counterparts, the mafic igneous intrusions record extensive bimodal magmatism along the northern NCC and in the XMOB during the Early to Middle Permian. The Mandula gabbroic rocks have low initial 87Sr/86Sr ratios (0.7040-0.7043) and positive εNd(t) (+6.2 to +7.3) and εHf(t) values (+13.4 to +14.5), resembling to those of contemporaneous Mandula basalts. These features, together with the presence of amphibole and the enrichment of large ion lithophile elements (LILE, e.g., Rb, Ba, U and Sr) and depletion of Nb-Ta suggest that the parental magmas of the Mandula mafic igneous rocks were derived from a depleted mantle source metasomatized by water-rich fluids. In contrast, the Xigedan gabbroic rocks are characterised by high 87Sr/86Sr ratios (0.7078-0.7080) and zircon δ18O values (5.84-6.61‰), but low εNd(t) (-9.3 to -10.2) and εHf(t) values (-8.76 to -8.54), indicative of a long-term enriched subcontinental lithosphere mantle source that was metasomatized by recycled, high δ18O crustal materials prior to partial melting. The high water contents (4.6-6.9 wt%) and arc-like geochemical signature (enrichment of fluid-mobile elements and depletion of Nb-Ta) of the parental magmas of the Xigedan gabbroic rocks further establish the existence of a mantle hydration event caused by fluid/melts released from hydrated recycled oceanic crust. Incompatible element modelling shows that 5-10% partial melting of an enriched mantle source by

  8. 12 Ministries Control Rare Earth Exports

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>"It is very natural to reserve rare earth as a strategic resource.Many countries do this,including China."On April 8,Sun Lihui,Vice Director of Metal Section of Chemicals Import & Export Commerce Chamber of China Minmetals Corporation told a reporter that as early as 2006,China has launched a strategic plan for rare earth,"but it was interrupted by the subsequent financial crisis."

  9. Earth Sciences Requirements for the Information Sciences Experiment System

    Science.gov (United States)

    Bowker, David E. (Editor); Katzberg, Steve J. (Editor); Wilson, R. Gale (Editor)

    1990-01-01

    The purpose of the workshop was to further explore and define the earth sciences requirements for the Information Sciences Experiment System (ISES), a proposed onboard data processor with real-time communications capability intended to support the Earth Observing System (Eos). A review of representative Eos instrument types is given and a preliminary set of real-time data needs has been established. An executive summary is included.

  10. Geosciences program annual report 1978. [LBL Earth Sciences Division

    Energy Technology Data Exchange (ETDEWEB)

    Witherspoon, P.A.

    1978-01-01

    This report is a reprint of the Geosciences section of the LBL Earth Sciences Division Annual Report 1978 (LBL-8648). It contains summary papers that describe fundamental studies addressing a variety of earth science problems of interest to the DOE. They have applications in such diverse areas as geothermal energy, oil recovery, in situ coal gasification, uranium resource evaluation and recovery, and earthquake prediction. Completed work has been reported or likely will be in the usual channels. (RWR)

  11. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  12. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  13. Advanced energy projects; FY 1995 research summaries

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-09-01

    The AEP Division supports projects to explore novel energy-related concepts which are typically at an early stage of scientific development, and high-risk, exploratory concepts. Topical areas presently receiving support are: novel materials for energy technology, renewable and biodegradable materials, exploring uses of new scientific discoveries, alternate pathways to energy efficiency, alternative energy sources, and innovative approaches to waste treatment and reduction. There were 46 research projects during FY 1995; ten were initiated during that fiscal year. The summaries are separated into grant and laboratory programs, and small business innovation research programs.

  14. School, Earth and Imagination

    Science.gov (United States)

    Merlini, Anna; Grieco, Giovanni; Oneta, Cristina

    2015-04-01

    Geology needs to be explained and narrated to the people, focusing on the goal of making that big change of mindset that will allow individuals and the entire community to tune into the timing and the ways in which the Earth evolves. In order to achieve these important goals it is necessary to educate children from an early age so that they learn to live an environmentally friendly life. With the project "School, Earth and imagination" we introduce, with a fun and new way, notions and topics in geological and environmental sciences in schools at all levels with the final goal of improving both knowledge and sensibility for these topics into the community. Through this project we start from the children (kindergarten and primary school, ages between 3 and 8 years) because they are the foundation of our society, and without foundations nothing can be built. The "School, Earth and imagination" project wants to give the children a real opportunity to approach reality and in general the surrounding environment, for the first time even before the traditional scholastic experience, with a scientific point of view, experimenting some basic physical concepts like temperature, weight, hardness and so on directly through their body. The project is structured and developed in modules that provide a high flexibility in order to meet needs and requirements of different schools in different situations. Each module is part of the journey of Mariolino, a character that represents a very curious child who introduces basic concepts associating them to geological processes. The Journey of Mariolino, as each module, follows an insistent scheme that starts from the presentation of the problem, follows with its discussion through direct questions and ends with experimentation of the hypotheses that children have proposed to validate the solution of the problem. Each module is independent and never ends without giving children a solution and is always structured with a practical activity

  15. Summary PhD

    NARCIS (Netherlands)

    Mare, de H.

    2005-01-01

    Comparative analysis of early modern Dutch arts (architecture, literature, painting). Development of a historical formalist method, based on historical source criticism, history of science and archaeology on the one hand and Russian formalism, French semiology and structuralism on the other hand.

  16. Summary PhD

    NARCIS (Netherlands)

    Mare, de H.

    2005-01-01

    Comparative analysis of early modern Dutch arts (architecture, literature, painting). Development of a historical formalist method, based on historical source criticism, history of science and archaeology on the one hand and Russian formalism, French semiology and structuralism on the other hand.

  17. Summaries of physical research in the geosciences

    Energy Technology Data Exchange (ETDEWEB)

    1980-08-01

    The Department of Energy supports research in the geosciences in order to provide a sound underlay of fundamental knowledge in those areas of the earth, atmospheric, and solar/terrestrial sciences that relate to the Department of Energy's many missions. The Division of Engineering, Mathematical and Geosciences, which is a part of the Office of Basic Energy Sciences and comes under the Director of Energy Research, supports under its Geosciences program major Department of Energy laboratories, industry, universities and other governmental agencies. The summaries in this document, prepared by the investigators, describe the overall scope of the individual programs and details of the research performed during 1979-1980. The Geoscience program includes research in geology, petrology, geophysics, geochemistry, hydrology, solar-terrestrial relationships, aeronomy, seismology and natural resource analysis, including the various subdivisions and interdisciplinary areas. All such research is related to the Department's technological needs, either directly or indirectly.

  18. The Nitrogen Budget of Earth

    CERN Document Server

    Johnson, Ben

    2015-01-01

    We comprehensively compile and review N content in geologic materials to calculate a new N budget for Earth. Using analyses of rocks and minerals in conjunction with N-Ar geochemistry demonstrates that the Bulk Silicate Earth (BSE) contains \\sim7\\pm4 times present atmospheric N (4\\times10^18 kg N, PAN), with 27\\pm16\\times10^18 kg N. Comparison to chondritic composition, after subtracting N sequestered into the core, yields a consistent result, with BSE N between 17\\pm13\\times10^18 kg to 31\\pm24\\times10^18 kg N. In the chondritic comparison we calculate a N mass in Earth's core (180\\pm110 to 300\\pm180\\times10^18 kg) and discuss the Moon as a proxy for the early mantle. Significantly, we find the majority of the planetary budget of N is in the solid Earth. The N estimate herein precludes the need for a "missing N" reservoir. Nitrogen-Ar systematics in mantle rocks and basalts identify two mantle reservoirs: MORB-source like (MSL) and high-N. High-N mantle is composed of young, N-rich material subducted from the...

  19. Earth and Terrestrial Planet Formation

    CERN Document Server

    Jacobson, Seth A

    2015-01-01

    The growth and composition of Earth is a direct consequence of planet formation throughout the Solar System. We discuss the known history of the Solar System, the proposed stages of growth and how the early stages of planet formation may be dominated by pebble growth processes. Pebbles are small bodies whose strong interactions with the nebula gas lead to remarkable new accretion mechanisms for the formation of planetesimals and the growth of planetary embryos. Many of the popular models for the later stages of planet formation are presented. The classical models with the giant planets on fixed orbits are not consistent with the known history of the Solar System, fail to create a high Earth/Mars mass ratio, and, in many cases, are also internally inconsistent. The successful Grand Tack model creates a small Mars, a wet Earth, a realistic asteroid belt and the mass-orbit structure of the terrestrial planets. In the Grand Tack scenario, growth curves for Earth most closely match a Weibull model. The feeding zon...

  20. EarthKAM

    Data.gov (United States)

    National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...

  1. Earth on the Move.

    Science.gov (United States)

    Naturescope, 1987

    1987-01-01

    Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)

  2. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  3. Delinquency Prevention Works. Program Summary.

    Science.gov (United States)

    Bilchik, Shay

    The Office of Juvenile Justice and Delinquency Prevention (OJJDP) compiled this summary in order to assist states and jurisdictions in their delinquency prevention efforts. The summary provides a synthesis of current information on a broad range of programs and strategies which seek to prevent delinquency. The theory of risk-focused prevention is…

  4. Summary of KOMPSAT-5 Calibration and Validation

    Science.gov (United States)

    Yang, D.; Jeong, H.; Lee, S.; Kim, B.

    2013-12-01

    Korean Multi-Purpose Satellite 5 (KOMPSAT-5), equipped with high resolution X-band (9.66 GHz) Synthetic Aperture Radar (SAR), is planning to be launched on August 22, 2013. With the satellite's primary mission objective being providing Geographical Information System (GIS), Ocean monitoring and Land management, and Disaster and ENvironment monitoring (GOLDEN), it is expected that its applications for scientific research on geographical processes will be extensive. In order to meet its mission objective, the KOMPSAT-5 will provide three different kinds of SAR imaging modes; High Resolution Mode (1 m resolution, 5 km swath), Standard Mode (3 m resolution, 30 km swath), and Wide Swath Mode (20 m resolution, 100 km swath). The KOMPSAT-5 will be operated in a 550 km sun-synchronous, dawn- dusk orbit with a 28-day ground repeat cycle providing valuable image information on Earth surface day-or-night and even in bad weather condition. After successful launch of the satellite, it will go through Launch and Early Operation (LEOP) and In-Orbit Testing (IOT) period about for 6 months to carry out various tests on satellite bus and payload systems. The satellite bus system will be tested during the first 3 weeks after the launch focusing on the Attitude and Orbit Control Subsystem (AOCS) and Integrated GPS Occultation Receiver (IGOR) calibration. With the completion of bus system test, the SAR payload system will be calibrated during initial In-Flight check period (11 weeks) by the joint effort of Thales Alenia Space Italy (TAS-I) and Korea Aerospace Research Institute (KARI). The pointing and relative calibration will be carried out during this period by analyzing the doppler frequency and antenna beam pattern of reflected microwave signal from selected regions with uniform backscattering coefficients (e.g. Amazon rainforest). A dedicated SAR calibration, called primary calibration, will be allocated at the end of LEOP for 12 weeks to perform thorough calibration activities

  5. Astronautics summary and prospects

    CERN Document Server

    Kiselev, Anatoly Ivanovich; Menshikov, Valery Alexandrovich

    2003-01-01

    The monograph by A.I.Kiselev, A.A. Medvedev and Y.A.Menshikov, Astronautics: Summary and Prospects, aroused enthusiasm both among experts and the public at large. This is due to the felicitous choice of presentation that combines a simple description of complex space matters with scientificsubstantiation of the sub­ jectmatter described. The wealth of color photos makes the book still more attractive, and it was nominated for an award at the 14th International Moscow Book Fair, being singled out as the "best publication of the book fair". The book's popularity led to a second edition, substantially revised and enlarged. Since the first edition did not sufficiently cover the issues of space impact on ecology and the prospective development of space systems, the authors revised the entire volume, including in it the chapter "Space activity and ecology" and the section "Multi-function space systems". Using the federal monitoring system, now in the phase of system engi­ neering, as an example, the authors consi...

  6. From Neurons to Neighborhoods: An Update--Workshop Summary

    Science.gov (United States)

    Olson, Steve

    2012-01-01

    "From Neurons to Neighborhoods: An Update: Workshop Summary" is based on the original study "From Neurons to Neighborhoods: Early Childhood Development," which was released in October of 2000. From the time of the original publication's release, much has occurred to cause a fundamental reexamination of the nation's…

  7. From Neurons to Neighborhoods: An Update--Workshop Summary

    Science.gov (United States)

    Olson, Steve

    2012-01-01

    "From Neurons to Neighborhoods: An Update: Workshop Summary" is based on the original study "From Neurons to Neighborhoods: Early Childhood Development," which was released in October of 2000. From the time of the original publication's release, much has occurred to cause a fundamental reexamination of the nation's…

  8. A Spherical Earth Solution for TOA Lightning Location Retrieval

    Science.gov (United States)

    Koshak, W. J.; Solakiewicz, R. J.

    1999-01-01

    The problem of retrieving ligntning, ground-strike location on a spherical Earth surface using a network of 4 or more time-of-arrival (TOA) sensors is considered, It is shown that this problem has an analytic solution and therefore does not require the use of nonlinear estimation theory (e.g., minimization). The mathematical robustness of the analytic solution is tested using computer-generated lightning sources and simulated TOA measurement errors. A summary of a quasi-analytic extension of the spherical Earth solution to an oblate spheroid Earth geometry is also provided.

  9. Capturing Near Earth Objects

    OpenAIRE

    Baoyin, Hexi; CHEN Yang; Li, Junfeng

    2011-01-01

    Recently, Near Earth Objects (NEOs) have been attracting great attention, and thousands of NEOs have been found to date. This paper examines the NEOs' orbital dynamics using the framework of an accurate solar system model and a Sun-Earth-NEO three-body system when the NEOs are close to Earth to search for NEOs with low-energy orbits. It is possible for such an NEO to be temporarily captured by Earth; its orbit would thereby be changed and it would become an Earth-orbiting object after a small...

  10. Summaries of FY 92 geosciences research

    Energy Technology Data Exchange (ETDEWEB)

    1992-12-01

    The Department of Energy supports research in the geosciences in order to provide a sound foundation of fundamental knowledge in those areas of the geosciences that are germane to the Department of Energy's many missions. The Division of Engineering and Geosciences, part of the Office of Basic Energy Sciences of the Office of Energy Research, supports the Geosciences Research Program. The participants in this program include Department of Energy laboratories, academic institutions, and other governmental agencies. These activities are formalized by a contract or grant between the Department of Energy and the organization performing the work, providing funds for salaries, equipment, research materials, and overhead. The summaries in this document, prepared by the investigators, describe the scope of the individual programs. The Geosciences Research Program includes research in geophysics, geochemistry, resource evaluation, solar-terrestrial interactions and their subdivisions including Earth dynamics, properties of Earth materials, rock mechanics, underground imaging, rock-fluid interactions, continental scientific drilling, geochemical transport, solar/atmospheric physics, and modeling, with emphasis on the interdisciplinary areas. All such research is related either directly or indirectly to the Department of Energy's long-range technological needs.

  11. Earth Sciences Division annual report 1990

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1991-06-01

    This Annual Report presents summaries of selected representative research activities grouped according to the principal disciplines of the Earth Sciences Division: Reservoir Engineering and Hydrogeology, Geology and Geochemistry, and Geophysics and Geomechanics. Much of the Division`s research deals with the physical and chemical properties and processes in the earth`s crust, from the partially saturated, low-temperature near-surface environment to the high-temperature environments characteristic of regions where magmatic-hydrothermal processes are active. Strengths in laboratory and field instrumentation, numerical modeling, and in situ measurement allow study of the transport of mass and heat through geologic media -- studies that now include the appropriate chemical reactions and the hydraulic-mechanical complexities of fractured rock systems. Of particular note are three major Division efforts addressing problems in the discovery and recovery of petroleum, the application of isotope geochemistry to the study of geodynamic processes and earth history, and the development of borehole methods for high-resolution imaging of the subsurface using seismic and electromagnetic waves. In 1989 a major DOE-wide effort was launched in the areas of Environmental Restoration and Waste Management. Many of the methods previously developed for and applied to deeper regions of the earth will in the coming years be turned toward process definition and characterization of the very shallow subsurface, where man-induced contaminants now intrude and where remedial action is required.

  12. Earth's core and the geodynamo

    Science.gov (United States)

    Buffett

    2000-06-16

    Earth's magnetic field is generated by fluid motion in the liquid iron core. Details of how this occurs are now emerging from numerical simulations that achieve a self-sustaining magnetic field. Early results predict a dominant dipole field outside the core, and some models even reproduce magnetic reversals. The simulations also show how different patterns of flow can produce similar external fields. Efforts to distinguish between the various possibilities appeal to observations of the time-dependent behavior of the field. Important constraints will come from geological records of the magnetic field in the past.

  13. Mineral Commodity Summaries 2008

    Science.gov (United States)

    ,

    2008-01-01

    Each chapter of the 2008 edition of the U.S. Geological Survey (USGS) Mineral Commodity Summaries (MCS) includes information on events, trends, and issues for each mineral commodity as well as discussions and tabular presentations on domestic industry structure, Government programs, tariffs, 5-year salient statistics, and world production and resources. The MCS is the earliest comprehensive source of 2007 mineral production data for the world. More than 90 individual minerals and materials are covered by two-page synopses. National reserves and reserve base information for most mineral commodities found in this report, including those for the United States, are derived from a variety of sources. The ideal source of such information would be comprehensive evaluations that apply the same criteria to deposits in different geographic areas and report the results by country. In the absence of such evaluations, national reserves and reserve base estimates compiled by countries for selected mineral commodities are a primary source of national reserves and reserve base information. Lacking national assessment information by governments, sources such as academic articles, company reports, common business practice, presentations by company representatives, and trade journal articles, or a combination of these, serve as the basis for national reserves and reserve base information reported in the mineral commodity sections of this publication. A national estimate may be assembled from the following: historically reported reserves and reserve base information carried for years without alteration because no new information is available; historically reported reserves and reserve base reduced by the amount of historical production; and company reported reserves. International minerals availability studies conducted by the U.S. Bureau of Mines, before 1996, and estimates of identified resources by an international collaborative effort (the International Strategic Minerals

  14. Anadromous fish inventory: Summary volume

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Summary volume, with discussion, on anadromous fish inventories, species lists, histories of fisheries, habitat, key spawning and rearing areas, runs/escapements,...

  15. Summary 2010 Greenhouse Gas Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — This file contains a summary of the publicly available data from the GHG Reporting Program for 2010. This data includes non-confidential data reported by facilities...

  16. Summary of The History Manifesto.

    Science.gov (United States)

    Jacobs, Noortje

    2016-06-01

    This essay provides a brief, impartial summary of some main points of The History Manifesto, of the debate among historians that it has engendered, and of its connection to previous debates in and about the history of the sciences.

  17. Lunar Core Drive Tubes Summary

    Data.gov (United States)

    National Aeronautics and Space Administration — Contains a brief summary and high resolution imagery from various lunar rock and core drive tubes collected from the Apollo and Luna missions to the moon.

  18. Long term performance session summary

    Energy Technology Data Exchange (ETDEWEB)

    Hanauer, S.

    1996-05-01

    This paper presents brief summaries of reports given on plutonium disposal. Topics include: performance of waste forms; glass leaching; ceramic leaching; safeguards and security issues; safeguards of vitrification; and proliferation risks of geologic disposal.

  19. Origin of the earth's ocean basins

    Science.gov (United States)

    Frey, H.

    1977-01-01

    The earth's original ocean basins are proposed to be mare-type basins produced 4 billion y.a. by the flux of asteroid-sized objects responsible for the lunar mare basins. Scaling upward from the observed number of lunar basins for the greater capture cross-section and impact velocity of the earth indicates that at least 50% of an original global crust would have been converted to basin topography. These basins were flooded by basaltic liquids in times short compared to the isostatic adjustment time for the basin. The modern crustal dichotomy (60% oceanic, 40% continental crust) was established early in the history of the earth, making possible the later onset of plate tectonic processes. These later processes have subsequently reworked, in several cycles, principally the oceanic parts of the earth's crust, changing the configuration of the continents in the process. Ocean basins (and oceans themselves) may be rare occurrences on planets in other star systems.

  20. Slant Borehole Demonstration Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    GARDNER, M.G.

    2000-07-19

    This report provides a summary of the demonstration project for development of a slant borehole to retrieve soil samples from beneath the SX-108 single-shell tank. It provides a summary of the findings from the demonstration activities and recommendations for tool selection and methods to deploy into the SX Tank Farm. Daily work activities were recorded on Drilling and Sampling Daily Work Record Reports. The work described in this document was performed during March and April 2000.

  1. Station Climatic Summaries, Latin America.

    Science.gov (United States)

    1987-11-01

    265 MEXICO - Acapulco 768056 8403 ................................ 267 Campeche 766950 8403................271 Chetumal 767500...0 0 1 # # I I # or I OPERATIONAL CLIMATIC DATA SUMMARY STATION: CHETUMAL , MEXICO STATIONS #: 767500 1CAO ID: NILC LOCATION: 18030’N, 88*18’W...0 0 0 0 0 0 # ALL HOURS I # # 1 # # # # # # 1 1 ]% OPERATIONAL CLIMATIC DATA SUMMARY SUPPLEMENT STATION: CHETUMAL , MEXICO STATIONS #: 767500 ICAO ID

  2. SUMMARY OF ARTICLES

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Marx formulated the dual logic of his early critical philosophy by criticizing religion and achieved the historical turn of research paradigm: the unity of the critique of political economy and the critique of speculative philosophy. It meant that there was intrinsic relevance of philosophy to history rather than philosophy became history itself. Philosophy got rid of the purely speculative nature and turned to historically research on the human existence. History was built on the foundation of philosophical study and became an important part of it. Beyond all previous theories about human history, Marx constructed a new historical interpretation scheme which unified the historical facts, the logic of history and historic human existence: a generative mode of historical interpretation scheme.

  3. Section I Summary

    Science.gov (United States)

    2016-01-01

    Shuttle Flight 41-C, the Solar Max Repair mission, took off on April 6, 1984 from Kennedy Space Center in Florida. As with 41-B, the dress rehearsal for this flight, launch was early in the morning. It occurred at 7:58 CST. The landing also took place at KSC the following Friday, April 13, 1984. This was Challenger's fifth flight. There were two prime EMU's and one back-up short EMU stowed for this flight in the Airlock. The two MMU's were again mounted in their Flight Support Stations in the payload bay. Figure 1 shows the EMU functional schematic while Figure 2 shows the hardware which makes up the EMU. The payload bay configuration for the MMU's appears in Figure 3.

  4. Astrobiology: Life on Earth (and Elsewhere?)

    Science.gov (United States)

    Des Marais, David J.

    2016-01-01

    Astrobiology investigates the origins, evolution and distribution of life in the universe. Scientists study how stellar systems and their planets can create planetary environments that sustain biospheres. They search for biosignatures, which are objects, substances and or patterns that indicate the presence of life. Studies of Earth's early biosphere enhance these search strategies and also provide key insights about our own origins.

  5. The Earth's Magnetic Field

    OpenAIRE

    Edda Lína Gunnarsdóttir 1988

    2012-01-01

    The Earth's magnetic field is essential for life on Earth, as we know it, to exist. It forms a magnetic shield around the planet, protecting it from high energy particles and radiation from the Sun, which can cause damage to life, power systems, orbiting satellites, astronauts and spacecrafts. This report contains a general overview of the Earth's magnetic field. The different sources that contribute to the total magnetic field are presented and the diverse variations in the field are describ...

  6. Mass Extinctions in Earth's History

    Science.gov (United States)

    Ward, P. D.

    2002-12-01

    Mass extinctions are short intervals of elevated species death. Possible causes of Earth's mass extinctions are both external (astronomical) and internal (tectonic and biotic changes from planetary mechanisms). Paleontologists have identified five "major" mass extinctions (>50 die-off in less than a million years) and more than 20 other minor events over the past 550 million years. Earlier major extinction events undoubtedly also occurred, but we have no fossil record; these were probably associated with, for example, the early heavy bombardment that cleared out the solar system, the advent of oxygen in the atmosphere, and various "snowball Earth" events. Mass extinctions are viewed as both destructive (species death ) and constructive, in that they allow evolutionary innovation in the wake of species disappearances. From an astrobiological perspective, mass extinctions must be considered as able both to reduce biodiversity and even potentially end life on any planet. Of the five major mass extinctions identified on Earth, only one (the Cretaceous/Tertiary event 65 million years ago that famously killed off the dinosaurs ) is unambiguously related to the impact of an asteroid or comet ( 10-km diameter). The Permian/Triassic (250 Myr ago) and Triassic/Jurassic (202 Myr ago) events are now the center of debate between those favoring impact and those suggesting large volume flooding by basaltic lavas. The final two events, Ordovician (440 Myr ago) and Devonian (370 Myr ago) have no accepted causal mechanisms.

  7. Engineering Annual Summary 1998

    Energy Technology Data Exchange (ETDEWEB)

    Dimolitsas, S

    1999-05-01

    Unlike most research and development laboratories, Lawrence Livermore National Laboratory (LLNL) is responsible for delivering production-ready designs. Unlike most industry, LLNL is responsible for R and D that must significantly increase the nation's security. This rare combination of production engineering expertise and national R and D agenda identifies LLNL as one of the few organizations today that conducts cutting-edge engineering on grand-scale problems, while facing enormous technical risk and undergoing diligent scrutiny of its budget, schedule, and performance. On the grand scale, cutting-edge technologies are emerging from our recent ventures into ''Xtreme Engineering{trademark}.'' Basically, we must integrate and extend technologies concurrently and then push them to their extreme, such as building very large structures but aligning them with extreme precision. As we extend these technologies, we push the boundaries of engineering capabilities at both poles: microscale and ultrascale. Today, in the ultrascale realm, we are building NIF, the world's largest laser, which demands one of the world's most complex operating systems with 9000 motors integrated through over 500 computers to control 60,000 points for every laser shot. On the other pole, we have fabricated the world's smallest surgical tools and the smallest instruments for detecting biological and chemical agents used by antiterrorists. Later in this Annual Summary, we highlight some of our recent innovations in the area of Xtreme Engineering, including large-scale computer simulations of massive structures such as major bridges to prepare retrofitting designs to withstand earthquakes. Another feature is our conceptual breakthrough in developing the world's fastest airplane, HyperSoar, which can reach anywhere in the planet in two hours at speeds of 6700 mph. In the last few years, Engineering has significantly pushed the technology in structural

  8. Engineering Annual Summary 1999

    Energy Technology Data Exchange (ETDEWEB)

    Dimolitsas, S.; Gerich, C.

    2000-04-11

    a 100 percent data capture rate. came to an end. Within an intense three-month period, Engineering effectively transitioned its 150 employees working on this project to other Laboratory projects. We leveraged our competence in microsystems and biosciences to establish a robust technical presence in the field of biological and chemical weapons defense. This year, we saw successful operational tests of several hand-held versions of our analytical instruments. Concurrently, we saw our efforts in information technologies and medical devices pay off significantly, when both these areas grew robustly. In the operations area, Engineering underwent an important change in its technology investment strategy. In 1998, we consolidated our nine technical thrust areas into five Engineering Technology Centers and restructured these centers to form the Engineering Science and Technology Program, reporting directly to my office. In 1999, we completed the selection of four of the five Directors to lead each of these areas and moved from startup to true enterprise. This 1999 Summary highlights these five Centers.

  9. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    , Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...... of starlight by the Sun, and therefore directly observe the structure of space-time. This thesis explores several aspects of the observation of NEOs with Gaia, emphasising detection of NEOs and the quality of orbits computed from Gaia observations. The main contribution is the work on motion detection...

  10. Timing And Processes Of Earth's Core Differentiation.

    Science.gov (United States)

    Allegre, C. J.; Manhes, G.; Gopel, C.

    2004-12-01

    Small 182W abundance excess of terrestrial W relative to W in bulk chondrites has been recently established (Yin et al. 2002, Kleine et al. 2002, Schoenberg et al. 2002). Rapid terrestrial accretion and early core formation, with completion of the bulk metal-silicate separation within less than 30 Myr have been proposed on this basis. These studies underline how much this 182W/182Hf time scale agrees with dynamic accretion models (Wetherill, 1986) that predict a ˜10 Myr interval for the main growth stage of Earth's formation. This W model time scale for terrestrial accretion is shorter than current estimates based on Pb isotope systematics of mantle-derived basalts and terrestrial Xe isotope systematics. The end of metal-silicate differentiation and large scale mantle degassing has been defined ˜100 My after beginning of the accretion. These studies also indicate agreement of this time scale with dynamic accretion models that predict 100 My for the end of Earth's accretion. The Hf-W time scale for accretion and core formation assumes total equilibration of incoming metal and silicate of impactors with the bulk silicate Earth (BSE) during planet's growth. Recently, the assumption of incomplete equilibration of metal and silicate components with BSE has been investigated (Halliday, 2004). It is proposed that impacting core material has not always efficiently mixed with the silicate portions of the Earth before being added to the Earth's core Our approach also considers that equilibration between metal and silicate has not been complete in BSE during Earth's growth, and we argue that early part of the Earth's core has segregated through unmelted silicate material. When the baby Earth was large enough, the increase of the temperature induced Fe-FeS eutectic melting. The liquid metal segregated through the crystalline silicate matrix and formed the early part of the Earth's core. Experimental study (Yoshino et al. 2003) indicates the percolation threshold for molten

  11. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  12. Summary and interpretive synthesis

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-05-01

    This chapter summarizes the major advances made through our integrated geological studies of the Lisburne Group in northern Alaska. The depositional history of the Lisburne Group is discussed in a framework of depositional sequence stratigraphy. Although individual parasequences (small-scale carbonate cycles) of the Wahoo Limestone cannot be correlated with certainty, parasequence sets can be interpreted as different systems tracts within the large-scale depositional sequences, providing insights on the paleoenvironments, paleogeography and platform geometry. Conodont biostratigraphy precisely established the position of the Mississippian-Pennsylvanian boundary within an important reference section, where established foraminiferal biostratigraphy is inconsistent with respect to conodont-based time-rock boundaries. However, existing Carboniferous conodont zonations are not readily applicable because most zonal indicators are absent, so a local zonation scheme was developed. Diagenetic studies of the Lisburne Group recognized nineteen subaerial exposure surfaces and developed a cement stratigraphy that includes: early cements associated with subaerial exposure surfaces in the Lisburne Group; cements associated with the sub-Permian unconformity; and later burial cements. Subaerial exposure surfaces in the Alapah Limestone are easily explained, being associated with peritidal environments at the boundaries of Sequence A. The Lisburne exposed in ANWR is generally tightly cemented and supermature, but could still be a good reservoir target in the adjacent subsurface of ANWR given the appropriate diagenetic, deformational and thermal history. Our ongoing research on the Lisburne Group will hopefully provide additional insights in future publications.

  13. Early Astronomy

    Science.gov (United States)

    Thurston, Hugh

    The earliest investigations that can be called scientific are concerned with the sky: they are the beginnings of astronomy. Many early civilizations produced astronomical texts, and several cultures that left no written records left monuments and artifacts-ranging from rock paintings to Stonehenge-that show a clear interest in astronomy. Civilizations in China, Mesopotamia, India and Greece had highly developed astronomies, and the astronomy of the Mayas was by no means negligible. Greek astronomy, as developed by the medieval Arab philosophers, evolved into the astronomy of Copernicus. This displaced the earth from the central stationary position that almost all earlier astronomies had assumed. Soon thereafter, in the first decades of the seventeenth century, Kepler found the true shape of the planetary orbits and Galileo introduced the telescope for astronomical observations.

  14. Contributions to global earth sciences integration. A special issue on the 3rd Young Earth Scientists Congress

    Science.gov (United States)

    Cónsole-Gonella, Carlos; Yidana, Sandow Mark

    2016-10-01

    The Young Earth Scientists (YES) Network is an association of early-career geoscientists who are primarily under the age of 35 years from universities, geoscience organizations and companies from across the world (http://www.networkyes.org)

  15. Jupyter meets Earth: Creating Comprehensible and Reproducible Scientific Workflows with Jupyter Notebooks and Google Earth Engine

    Science.gov (United States)

    Erickson, T.

    2016-12-01

    Deriving actionable information from Earth observation data obtained from sensors or models can be quite complicated, and sharing those insights with others in a form that they can understand, reproduce, and improve upon is equally difficult. Journal articles, even if digital, commonly present just a summary of an analysis that cannot be understood in depth or reproduced without major effort on the part of the reader. Here we show a method of improving scientific literacy by pairing a recently developed scientific presentation technology (Jupyter Notebooks) with a petabyte-scale platform for accessing and analyzing Earth observation and model data (Google Earth Engine). Jupyter Notebooks are interactive web documents that mix live code with annotations such as rich-text markup, equations, images, videos, hyperlinks and dynamic output. Notebooks were first introduced as part of the IPython project in 2011, and have since gained wide acceptance in the scientific programming community, initially among Python programmers but later by a wide range of scientific programming languages. While Jupyter Notebooks have been widely adopted for general data analysis, data visualization, and machine learning, to date there have been relatively few examples of using Jupyter Notebooks to analyze geospatial datasets. Google Earth Engine is cloud-based platform for analyzing geospatial data, such as satellite remote sensing imagery and/or Earth system model output. Through its Python API, Earth Engine makes petabytes of Earth observation data accessible, and provides hundreds of algorithmic building blocks that can be chained together to produce high-level algorithms and outputs in real-time. We anticipate that this technology pairing will facilitate a better way of creating, documenting, and sharing complex analyses that derive information on our Earth that can be used to promote broader understanding of the complex issues that it faces. http://jupyter.orghttps://earthengine.google.com

  16. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  17. The Earth's Core.

    Science.gov (United States)

    Jeanloz, Raymond

    1983-01-01

    The nature of the earth's core is described. Indirect evidence (such as that determined from seismological data) indicates that it is an iron alloy, solid toward its center but otherwise liquid. Evidence also suggests that it is the turbulent flow of the liquid that generates the earth's magnetic field. (JN)

  18. Solid Earth: Introduction

    Science.gov (United States)

    Rummel, R.

    1991-10-01

    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  19. Wind energy systems: program summary

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-05-01

    The Federal Wind Energy Program (FWEP) was initiated to provide focus, direction and funds for the development of wind power. Each year a summary is prepared to provide the American public with an overview of government sponsored activities in the FWEP. This program summary describes each of the Department of Energy's (DOE) current wind energy projects initiated or renewed during FY 1979 (October 1, 1978 through September 30, 1979) and reflects their status as of April 30, 1980. The summary highlights on-going research, development and demonstration efforts and serves as a record of progress towards the program objectives. It also provides: the program's general management structure; review of last year's achievements; forecast of expected future trends; documentation of the projects conducted during FY 1979; and list of key wind energy publications.

  20. Wind energy systems: program summary

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-05-01

    The Federal Wind Energy Program (FWEP) was initiated to provide focus, direction and funds for the development of wind power. Each year a summary is prepared to provide the American public with an overview of government sponsored activities in the FWEP. This program summary describes each of the Department of Energy's (DOE) current wind energy projects initiated or renewed during FY 1979 (October 1, 1978 through September 30, 1979) and reflects their status as of April 30, 1980. The summary highlights on-going research, development and demonstration efforts and serves as a record of progress towards the program objectives. It also provides: the program's general management structure; review of last year's achievements; forecast of expected future trends; documentation of the projects conducted during FY 1979; and list of key wind energy publications.

  1. Housing Summaries (2005-2009)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The American Community Survey (ACS) is a nationwide survey conducted by the U.S. Census Bureau that is designed to provide communities a fresh look at how they are...

  2. Economic Summaries (2005-2009)

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The American Community Survey (ACS) is a nationwide survey conducted by the U.S. Census Bureau that is designed to provide communities a fresh look at how they are...

  3. Advanced Energy Projects FY 1996 research summaries

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    The mission of the Advanced Energy Projects Division (AEP) is to explore the scientific feasibility of novel energy-related concepts. These concepts are typically at an early stage of scientific development and, therefore, are premature for consideration by applied research or technology development programs. The portfolio of projects is dynamic, but reflects the broad role of the Department in supporting research and development for improving the Nation`s energy posture. Topical areas presently receiving support include: alternative energy sources; innovative concepts for energy conversion and storage; alternate pathways to energy efficiency; exploring uses of new scientific discoveries; biologically-based energy concepts; renewable and biodegradable materials; novel materials for energy technology; and innovative approaches to waste treatment and reduction. Summaries of the 70 projects currently being supported are presented. Appendices contain budget information and investigator and institutional indices.

  4. Final summary report. [Summaries of research activities at Cornell University

    Energy Technology Data Exchange (ETDEWEB)

    Krumhansl, J A

    1978-01-01

    A summary is presented of the topics covered during the period, from 1960 to 1978, of the contract. The general area of the research has been theoretical solid state physics. A list of publications produced during the contract is given. (GHT)

  5. Earth System Oxygenation: Toward an Integrated Theory of Earth Evolution

    Science.gov (United States)

    Anbar, A. D.

    2015-12-01

    The cause of the progressive oxygenation of Earth's biosphere remains poorly understood. The problem is bounded by the interplay of three irreversible, secular changes: the escape of H to space, which makes the planet more oxidized; the evolution of photoautotrophy - which converts solar energy into redox disequilbrium - and related metabolisms; and the cooling of the planet, which affects the exchange of material between Earth's reduced interior and relatively oxidized surface through a variety of processes. The first of these changes is quantitatively considered elsewhere, and is connected to the other two because H escape depends on atmospheric H2 and CH4 contents. The second of these changes is an area of vigorous research, particularly over the past decade. Important work included efforts to constrain the timing of key evolutionary events using organic geochemical and genomic records, and to understand the timing and tempo of environmental oxidation, particularly preceding the "Great Oxidation Event" (GOE) at ~2.4 Ga. As the community sorts through various debates, evidence is accumulating that the pre-GOE period was a dynamic era of transient "whiffs" of oxidation, most likely due to small amounts of biogenic O2 that appeared as early as ~3.0 Ga. The implication is that O2 sinks generally overwhelmed substantial O2 sources through the first half of Earth history, and that a decrease in sink strength and/or increase in source strength could have resulted in increasing instability of trace pO2 in the runup to the GOE. The most likely sinks are coupled to reductants in Earth's interior, which leads us to the third major change—secular cooling of the planet. It is almost certain that this cooling led to changes in mantle dynamics, rates of plate motion, and melting behaviors, which in turn affected volcanism, crust composition, hydrothermal and metamorphic alteration, ocean nutrient budgets, and recycling at subduction zones. These factors have all been

  6. Experimental plasma research project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-01

    This report contans descriptions of the activities supported by the Experimental Plasma Research Branch of APP. The individual project summaries were prepared by the principal investigators and include objectives and milestones for each project. The projects are arranged in six research categories: Plasma Properties; Plasma Heating; Plasma Measurements and Instrumentation; Atomic, Molecular and Nuclear Physics; Advanced Superconducting Materials; and the Fusion Plasma Research Facility (FPRF). Each category is introduced with a statement of objectives and recent progress and followed by descriptions of individual projects. An overall budget summary is provided at the beginning of the report.

  7. Experimental Plasma Research project summaries

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    This report contains descriptions of the activities supported by the Experimental Plasma Research Branch of APP. The individual project summaries were prepared by the principal investigators and include objectives and milestones for each project. The projects are arranged in six research categories: Plasma Properties; Plasma Heating; Plasma Diagnostics; Atomic, Molecular and Nuclear Physics; Advanced Superconducting Materials; and the Fusion Plasma Research Facility (FPRF). Each category is introduced with a statement of objectives and recent progress and followed by descriptions of individual projects. An overall budget summary is provided at the beginning of the report.

  8. Earth from Space: The Power of Perspective

    Science.gov (United States)

    Abdalati, W.

    2016-12-01

    Throughout history, humans have always valued the view from above, seeking high ground to survey the land, find food, assess threats, and understand their immediate environment. The advent of aircraft early in the 20th century took this capability literally to new levels, as aerial photos of farm lands, hazards, military threats, etc. provided new opportunities for security and prosperity. And in 1960, with the launch of the first weather satellite, TIROS, we came to know our world in ways that were not possible before, as we saw the Earth as a system of interacting components. In the decades since, our ability to understand the Earth System and its dynamic components has been transformed profoundly and repeatedly by satellite observations. From examining changes in sea level, to deformation of the Earth surface, to ozone depletion, to the Earth's energy balance, satellites have helped us understand our changing planet in ways that would not have otherwise been possible. The challenge moving forward is to continue to evolve beyond watching Earth processes unfold and understanding the underlying mechanisms of change, to anticipating future conditions, more comprehensively than we do today, for the benefit of society. The capabilities to do so are well within our reach, and with appropriate investments in observing systems, research, and activities that support translating observations into societal value, we can realize the full potential of this tremendous space-based perspective. Doing so will not just change our views of the Earth, but will improve our relationship with it.

  9. Earth as art three

    Science.gov (United States)

    ,

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  10. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  11. Accretion of the Earth.

    Science.gov (United States)

    Canup, Robin M

    2008-11-28

    The origin of the Earth and its Moon has been the focus of an enormous body of research. In this paper I review some of the current models of terrestrial planet accretion, and discuss assumptions common to most works that may require re-examination. Density-wave interactions between growing planets and the gas nebula may help to explain the current near-circular orbits of the Earth and Venus, and may result in large-scale radial migration of proto-planetary embryos. Migration would weaken the link between the present locations of the planets and the original provenance of the material that formed them. Fragmentation can potentially lead to faster accretion and could also damp final planet orbital eccentricities. The Moon-forming impact is believed to be the final major event in the Earth's accretion. Successful simulations of lunar-forming impacts involve a differentiated impactor containing between 0.1 and 0.2 Earth masses, an impact angle near 45 degrees and an impact speed within 10 per cent of the Earth's escape velocity. All successful impacts-with or without pre-impact rotation-imply that the Moon formed primarily from material originating from the impactor rather than from the proto-Earth. This must ultimately be reconciled with compositional similarities between the Earth and the Moon.

  12. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.

  13. Earth Science Informatics - Overview

    Science.gov (United States)

    Ramapriyan, H. K.

    2017-01-01

    Over the last 10-15 years, significant advances have been made in information management, there are an increasing number of individuals entering the field of information management as it applies to Geoscience and Remote Sensing data, and the field of informatics has come to its own. Informatics is the science and technology of applying computers and computational methods to the systematic analysis, management, interchange, and representation of science data, information, and knowledge. Informatics also includes the use of computers and computational methods to support decision making and applications. Earth Science Informatics (ESI, a.k.a. geoinformatics) is the application of informatics in the Earth science domain. ESI is a rapidly developing discipline integrating computer science, information science, and Earth science. Major national and international research and infrastructure projects in ESI have been carried out or are on-going. Notable among these are: the Global Earth Observation System of Systems (GEOSS), the European Commissions INSPIRE, the U.S. NSDI and Geospatial One-Stop, the NASA EOSDIS, and the NSF DataONE, EarthCube and Cyberinfrastructure for Geoinformatics. More than 18 departments and agencies in the U.S. federal government have been active in Earth science informatics. All major space agencies in the world, have been involved in ESI research and application activities. In the United States, the Federation of Earth Science Information Partners (ESIP), whose membership includes over 180 organizations (government, academic and commercial) dedicated to managing, delivering and applying Earth science data, has been working on many ESI topics since 1998. The Committee on Earth Observation Satellites (CEOS)s Working Group on Information Systems and Services (WGISS) has been actively coordinating the ESI activities among the space agencies.The talk will present an overview of current efforts in ESI, the role members of IEEE GRSS play, and discuss

  14. Fourteen Times the Earth

    Science.gov (United States)

    2004-08-01

    ESO HARPS Instrument Discovers Smallest Ever Extra-Solar Planet Summary A European team of astronomers [1] has discovered the lightest known planet orbiting a star other than the sun (an "exoplanet"). The new exoplanet orbits the bright star mu Arae located in the southern constellation of the Altar. It is the second planet discovered around this star and completes a full revolution in 9.5 days. With a mass of only 14 times the mass of the Earth, the new planet lies at the threshold of the largest possible rocky planets, making it a possible super Earth-like object. Uranus, the smallest of the giant planets of the Solar System has a similar mass. However Uranus and the new exoplanet differ so much by their distance from the host star that their formation and structure are likely to be very different. This discovery was made possible by the unprecedented accuracy of the HARPS spectrograph on ESO's 3.6-m telescope at La Silla, which allows radial velocities to be measured with a precision better than 1 m/s. It is another clear demonstration of the European leadership in the field of exoplanet research. PR Photo 25a/04: The HARPS Spectrograph and the 3.6m Telescope PR Photo 25b/04: Observed Velocity Variation of mu Arae (3.6m/HARPS, 1.2m Swiss/CORALIE, AAT/UCLES) PR Photo 25c/04: Velocity Variation of mu Arae Observed by HARPS (3.6m/HARPS) PR Photo 25d/04: "Velocity Curve" of mu Arae A unique planet hunting machine ESO PR Photo 25a/04 ESO PR Photo 25a/04 The HARPS Spectrograph and the 3.6m Telescope [Preview - JPEG: 602 x 400 pix - 211k] [Normal - JPEG: 1202 x 800 pix - 645k] Caption: ESO PR Photo 25a/04 represents a montage of the HARPS spectrograph and the 3.6m telescope at La Silla. The upper left shows the dome of the telescope, while the upper right illustrates the telescope itself. The HARPS spectrograph is shown in the lower image during laboratory tests. The vacuum tank is open so that some of the high-precision components inside can be seen. Since the first

  15. Earth before life.

    Science.gov (United States)

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-09

    A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome includes the age of the Earth are consistent with observed data. The appearance of life after the formation of the Earth is consistent with the data set under examination.

  16. Philadelphia's Renaissance Schools: Start up and Early Implementation. Executive Summary

    Science.gov (United States)

    Research for Action, 2011

    2011-01-01

    In April 2009, Superintendent Arlene Ackerman announced her reform plan for the School District of Philadelphia (the District)--"Imagine 2014". Among other major initiatives, "Imagine 2014" laid the groundwork for Philadelphia's Renaissance Schools Initiative. The Renaissance Initiative, set to enter its second year in 2011-12, is an effort to…

  17. Biomass energy systems program summary

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-07-01

    Research programs in biomass which were funded by the US DOE during fiscal year 1978 are listed in this program summary. The conversion technologies and their applications have been grouped into program elements according to the time frame in which they are expected to enter the commercial market. (DMC)

  18. Whole-Earth Decompression Dynamics

    OpenAIRE

    Herndon, J. Marvin

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The i...

  19. Computer software summaries. Numbers 325 through 423

    Energy Technology Data Exchange (ETDEWEB)

    1978-08-01

    The National Energy Software Center (NESC) serves as the software exchange and information center for the U.S. Department of Energy and the Nuclear Regulatory Commission. These summaries describe agency-sponsored software which is at the specification stage, under development, being checked out, in use, or available at agency offices, laboratories, and contractor installations. They describe software which is not included in the NESC library due to its preliminary status or because it is believed to be of limited interest. Codes dealing with the following subjects are included: cross section and resonance integral calculations; spectrum calculations, generation of group constants, lattice and cell problems; static design studies; depletion, fuel management, cost analysis, and power plant economics; space-independent kinetics; space--time kinetics, coupled neutronics--hydrodynamics--thermodynamics; and excursion simulations; radiological safety, hazard and accident analysis; heat transfer and fluid flow; deformation and stress distribution computations, structural analysis, and engineering design studies; gamma heating and shield design; reactor systems analysis; data preparation; data management; subsidiary calculations; experimental data processing; general mathematical and computing system routines; materials; environmental and earth sciences; space sciences; electronics and engineering equipment; chemistry; particle accelerators and high-voltage machines; physics; magnetic fusion research; biology and medicine; and data. (RWR)

  20. Gambling with the earth

    CERN Multimedia

    Muir, H

    2000-01-01

    The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).

  1. Astronomy: Earth's seven sisters

    Science.gov (United States)

    Snellen, Ignas A. G.

    2017-02-01

    Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets. See Letter p.456

  2. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ July 20~31 Rare earth market still went downward, which was mainly led by sluggish demand for didymium products. Weak demand by domestic NdFeB market was attributed to continuous price falling of didymium mischmetal.

  3. Analyzing earth's surface data

    Science.gov (United States)

    Barr, D. J.; Elifrits, C. D.

    1979-01-01

    Manual discusses simple inexpensive image analysis technique used to interpret photographs and scanner of data of Earth's surface. Manual is designed for those who have no need for sophisticated computer-automated analysis procedures.

  4. Managing Planet Earth.

    Science.gov (United States)

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  5. Earliest life on earth

    CERN Document Server

    Golding, Suzanne D

    2010-01-01

    This volume integrates the latest findings on earliest life forms, identified and characterized in some of the oldest rocks on Earth. It places emphasis on the integration of analytical methods with observational techniques and experimental simulations.

  6. Earth/Lands

    OpenAIRE

    2011-01-01

    Earth is an essentially original and misunderstood raw material with great potential, from the positive environmental and energy ratio, to its admirable capacity to integrate other materials such as stone, wood, brick, lime, vegetable fibres, etc., capable also of constituting the sole material for whole buildings in climactical and geographically extreme situations. Earth offers a great capacity to respond to the housing needs of millions of human beings, not only quantitative needs compa...

  7. Toward other Earths

    Science.gov (United States)

    Hatzes, Artie P.

    2016-04-01

    How common are habitable Earth-like planets? This is a key question that drives much of current research in exoplanets. To date, we have discovered over one thousand exoplanets, mostly through the transit method. Among these are Earth-size planets, but these orbit very close to the star (semi-major axis approximately 0.01 Astronomical Units). Potentially rocky planets have also been discovered in a star's habitable zone, but these have approximately twice the radius of the Earth. These certainly do not qualify as Earth "twins". Several hundreds of multi-planet systems have also been discovered, but these are mostly ultra-compact systems with up to seven planets all with orbital distances less than that of Mercury in our solar system. The detection of a planetary system that is the direct analog of our solar system still eludes us. After an overview of the current status of exoplanet discoveries I will discuss the prospects and challenges of finding such Earth analogs from the ground and from future space missions like PLATO. After over two decades of searching, we may well be on the brink of finding other Earths.

  8. A nucleosynthetic origin for the Earth's anomalous (142)Nd composition.

    Science.gov (United States)

    Burkhardt, C; Borg, L E; Brennecka, G A; Shollenberger, Q R; Dauphas, N; Kleine, T

    2016-09-15

    A long-standing paradigm assumes that the chemical and isotopic compositions of many elements in the bulk silicate Earth are the same as in chondrites. However, the accessible Earth has a greater (142)Nd/(144)Nd ratio than do chondrites. Because (142)Nd is the decay product of the now-extinct (146)Sm (which has a half-life of 103 million years), this (142)Nd difference seems to require a higher-than-chondritic Sm/Nd ratio for the accessible Earth. This must have been acquired during global silicate differentiation within the first 30 million years of Solar System formation and implies the formation of a complementary (142)Nd-depleted reservoir that either is hidden in the deep Earth, or lost to space by impact erosion. Whether this complementary reservoir existed, and whether or not it has been lost from Earth, is a matter of debate, and has implications for determining the bulk composition of Earth, its heat content and structure, as well as for constraining the modes and timescales of its geodynamical evolution. Here we show that, compared with chondrites, Earth's precursor bodies were enriched in neodymium that was produced by the slow neutron capture process (s-process) of nucleosynthesis. This s-process excess leads to higher (142)Nd/(144)Nd ratios; after correction for this effect, the (142)Nd/(144)Nd ratios of chondrites and the accessible Earth are indistinguishable within five parts per million. The (142)Nd offset between the accessible silicate Earth and chondrites therefore reflects a higher proportion of s-process neodymium in the Earth, and not early differentiation processes. As such, our results obviate the need for hidden-reservoir or super-chondritic Earth models and imply a chondritic Sm/Nd ratio for the bulk Earth. Although chondrites formed at greater heliocentric distances and contain a different mix of presolar components than Earth, they nevertheless are suitable proxies for Earth's bulk chemical composition.

  9. Early menarche, nulliparity and the risk for premature and early natural menopause

    DEFF Research Database (Denmark)

    Mishra, Gita D; Pandeya, Nirmala; Dobson, Annette J

    2017-01-01

    STUDY QUESTION: Are parity and the timing of menarche associated with premature and early natural menopause? SUMMARY ANSWER: Early menarche (≤11 years) is a risk factor for both premature menopause (final menstrual period, FMP <40 years) and early menopause (FMP 40-44 years), a risk that is ampli...

  10. U.S. Annual Climatological Summaries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Annual Climatological Summary contains historical monthly and annual summaries for over 8000 U.S. locations. Observing stations are located in the United States of...

  11. Visualizing Summary Statistics and Uncertainty

    KAUST Repository

    Potter, K.

    2010-08-12

    The graphical depiction of uncertainty information is emerging as a problem of great importance. Scientific data sets are not considered complete without indications of error, accuracy, or levels of confidence. The visual portrayal of this information is a challenging task. This work takes inspiration from graphical data analysis to create visual representations that show not only the data value, but also important characteristics of the data including uncertainty. The canonical box plot is reexamined and a new hybrid summary plot is presented that incorporates a collection of descriptive statistics to highlight salient features of the data. Additionally, we present an extension of the summary plot to two dimensional distributions. Finally, a use-case of these new plots is presented, demonstrating their ability to present high-level overviews as well as detailed insight into the salient features of the underlying data distribution. © 2010 The Eurographics Association and Blackwell Publishing Ltd.

  12. ENDF/B summary documentation

    Energy Technology Data Exchange (ETDEWEB)

    Kinsey, R. (comp.)

    1979-07-01

    This publication provides a localized source of descriptions for the evaluations contained in the ENDF/B Library. The summary documentation presented is intended to be a more detailed description than the (File 1) comments contained in the computer readable data files, but not so detailed as the formal reports describing each ENDF/B evaluation. The summary documentations were written by the CSEWB (Cross Section Evaluation Working Group) evaluators and compiled by NNDC (National Nuclear Data Center). This edition includes documentation for materials found on ENDF/B Version V tapes 501 to 516 (General Purpose File) excluding tape 504. ENDF/B-V also includes tapes containing partial evaluations for the Special Purpose Actinide (521, 522), Dosimetry (531), Activation (532), Gas Production (533), and Fission Product (541-546) files. The materials found on these tapes are documented elsewhere. Some of the evaluation descriptions in this report contain cross sections or energy level information. (RWR)

  13. Summary

    OpenAIRE

    2017-01-01

    Ecuador is a mountainous, volcanic country typical of the tropical part of the Andes range. The situation in the mountains—the Sierra—is special. Following an agrarian reform process with questionable results, many small farmers were shifted to slopes and highland areas, where many small cropped fields form a checkerboard pattern with low productivity, the «minifundio». This highland agrosystem enhances the acceleration of soil erosion in a mountain environment where this type of risk is natu...

  14. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Zhao Chuanjun The chaos from the unending Arab spring to Indian Hazare hunger strike is directly or indirectly closely connected with corruption, which has evolved into a general social phenomenon in Russia. As China and Russia are both transitional countries confronted with a stern anti -corruption situation. A deep seated probe on Russia' s corruption and harms as well as its anti - corruption means would be highly revealing to us.

  15. SUMMARY

    African Journals Online (AJOL)

    economic hardships and cost recovery programs associated with structural adjustment programs ... services, decline in the coverage of child immunisations, inability of the public health ..... 31), complaints of frequent and often prolonged.

  16. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Liu qingcai and Qiao Rui During the Yehsin' s time, president' s republic was established according to federalism and separation of the three powers. Putin made efforts to consolidate federal power system and to improve Duma and party system during his first presidency. Medvedev carried out reforms to stabilize state' s power and to promote political democratization during his time in Kremlin. During his third term, Putin pur- sues the balance between powerful state and people' s democracy and builds a unitary, stable, democratic and impartial system.

  17. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Zhang Shengfa Grave divergence exists between Putin and Medededev on historical and realistic problems. The essence of their divergence is the difference and antagonism on different values, world outlook and state governance rooted from their different wo

  18. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Feng Yujun, Wang Cong & Shang Yue 2011 was the 20th year of Central Asian states gaining sovereignty and independence and lenges, and making efforts to pushing social transition, and also a year of key importance in meeting all chalsafeguard stability and promote development.

  19. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Department of Commerce: Pork Prices Continue to Fall, While Egg Prices Start to Rise The data of Commerce Department shows that pork prices, one of agricultural products monitored the Ministry of Commerce on July 25 to 31, are 0.5% lower than the prices in last week (the same below), which was pork prices' continuous price fall for two weeks since the pork prices continued to increase since May. Meanwhile, egg prices continued to rise about 0.8% in last week, which have been rising for 6 weeks.

  20. SUMMARY

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Liu Siangwen & Zhao Xiaoyi On December 12, 1993 the Russian Federation adopted The Constitu- tion of the Russian Federation in the form of public referendum. As the fruition of its bourgeois revolution, Constitution has laid down the constitutional foundation of capitalist constitutional development. This is mainly manifested in : (a) Pointing out the orientation of its advance as a capitalist constitutional country, (b) Guar- anteeing the firm orientation of advance with strict constitutional procedural amendmen the semi - president system, conferring on the president great powers so as to speed up constitutional system development. ts, th and (c) Confirming e process of capitalist

  1. Station Climatic Summaries, Latin America

    Science.gov (United States)

    1990-06-01

    1 ARUBA Reina Beatrix 789820 Dec 86 (OCDS) --....................................... 5 ARGENTINA Buenos Alres/Ezeiza 875760 Apr 89 (CB...74 Oruro/Mendoza 852420 Feb 87 (OCDS) ...................................... 78 Potosi/ Rojas 852930 Feb 87 (OCDS...F 0 0 0 f 21-23 LST 0 0 0 0 # 0 F 1 0 0 0 F ALL HOURS # f F 0 0 # 0 F F 0 0 0 F 004 OPERATIONAL CLIMATIC DATA SUMMARY STATION: REINA BEATRIX INTL

  2. Experimental Summary Moriond QCD 2008

    CERN Document Server

    de Roeck, Albert

    2008-01-01

    2008 was a vintage year for the QCD Moriond meeting. Plenty of new data from Tevatron, HERA, B-Factories and other experiments have been reported. Some brand new results became public just before or even during the conference. A few new hints for New Physics came up in Winter 2008, but these await further scrutiny. This paper is the write-up of the experimental summary talk given at the Moriond QCD March meeting.

  3. Separations innovative concepts: Project summary

    Energy Technology Data Exchange (ETDEWEB)

    Lee, V.E. (ed.)

    1988-05-01

    This project summary includes the results of 10 innovations that were funded under the US Department's Innovative Concept Programs. The concepts address innovations that can substantially reduce the energy used in industrial separations. Each paper describes the proposed concept, and discusses the concept's potential energy savings, market applications, technical feasibility, prior work and state of the art, and future development needs.

  4. Compact Visualisation of Video Summaries

    Directory of Open Access Journals (Sweden)

    Ćalić Janko

    2007-01-01

    Full Text Available This paper presents a system for compact and intuitive video summarisation aimed at both high-end professional production environments and small-screen portable devices. To represent large amounts of information in the form of a video key-frame summary, this paper studies the narrative grammar of comics, and using its universal and intuitive rules, lays out visual summaries in an efficient and user-centered way. In addition, the system exploits visual attention modelling and rapid serial visual presentation to generate highly compact summaries on mobile devices. A robust real-time algorithm for key-frame extraction is presented. The system ranks importance of key-frame sizes in the final layout by balancing the dominant visual representability and discovery of unanticipated content utilising a specific cost function and an unsupervised robust spectral clustering technique. A final layout is created using an optimisation algorithm based on dynamic programming. Algorithm efficiency and robustness are demonstrated by comparing the results with a manually labelled ground truth and with optimal panelling solutions.

  5. Moriond QCD 2013 Experimental Summary

    CERN Document Server

    Denisov, Dmitri

    2013-01-01

    The article presents experimental highlights of Moriond 2013 QCD conference. This was fantastic conference and the first Moriond QCD since the discovery of the Higgs boson. Many new results about its properties have been presented at the conference with Higgs-like particle becoming a Higgs as it properties match expected for the Higgs boson pretty well. There were many new results presented in all experimental areas including QCD, elecroweak, studies of the top, bottom and charm quarks, searches for physics beyond Standard Model as well as studies of the heavy ion collisions. 56 experimental talks have been presented at the conference and it is impossible to cover each result in the summary, so highlights are limited to what I was able to present in my summary talk presented on March 16 2013. The proceedings of the conference cover in depth all talks presented and I urge you to get familiar with all of them. Theoretical Summary of the conference was given by Michelangelo Mangano, so theory talks are not cover...

  6. Moriond QCD 2013 Experimental Summary

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, Dmitri [Fermilab

    2013-06-28

    The article presents experimental highlights of Moriond 2013 QCD conference. This was fantastic conference and the first Moriond QCD since the discovery of the Higgs boson. Many new results about its properties have been presented at the conference with Higgs-like particle becoming a Higgs as it properties match expected for the Higgs boson pretty well. There were many new results presented in all experimental areas including QCD, elecroweak, studies of the top, bottom and charm quarks, searches for physics beyond Standard Model as well as studies of the heavy ion collisions. 56 experimental talks have been presented at the conference and it is impossible to cover each result in the summary, so highlights are limited to what I was able to present in my summary talk presented on March 16 2013. The proceedings of the conference cover in depth all talks presented and I urge you to get familiar with all of them. Theoretical Summary of the conference was given by Michelangelo Mangano, so theory talks are not covered in the article.

  7. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  8. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  9. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  10. 40 CFR 25.8 - Responsiveness summaries.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 1 2010-07-01 2010-07-01 false Responsiveness summaries. 25.8 Section... ACT § 25.8 Responsiveness summaries. Each agency which conducts any activities required under this part shall prepare a Responsiveness Summary at specific decision points as specified in program...

  11. NASA's Earth science flight program status

    Science.gov (United States)

    Neeck, Steven P.; Volz, Stephen M.

    2010-10-01

    NASA's strategic goal to "advance scientific understanding of the changing Earth system to meet societal needs" continues the agency's legacy of expanding human knowledge of the Earth through space activities, as mandated by the National Aeronautics and Space Act of 1958. Over the past 50 years, NASA has been the world leader in developing space-based Earth observing systems and capabilities that have fundamentally changed our view of our planet and have defined Earth system science. The U.S. National Research Council report "Earth Observations from Space: The First 50 Years of Scientific Achievements" published in 2008 by the National Academy of Sciences articulates those key achievements and the evolution of the space observing capabilities, looking forward to growing potential to address Earth science questions and enable an abundance of practical applications. NASA's Earth science program is an end-to-end one that encompasses the development of observational techniques and the instrument technology needed to implement them. This includes laboratory testing and demonstration from surface, airborne, or space-based platforms; research to increase basic process knowledge; incorporation of results into complex computational models to more fully characterize the present state and future evolution of the Earth system; and development of partnerships with national and international organizations that can use the generated information in environmental forecasting and in policy, business, and management decisions. Currently, NASA's Earth Science Division (ESD) has 14 operating Earth science space missions with 6 in development and 18 under study or in technology risk reduction. Two Tier 2 Decadal Survey climate-focused missions, Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) and Surface Water and Ocean Topography (SWOT), have been identified in conjunction with the U.S. Global Change Research Program and initiated for launch in the 2019

  12. Better Than Earth

    CERN Document Server

    Heller, René

    2015-01-01

    Do We Inhabit The Best O All Possible Worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  13. Better Than Earth

    Science.gov (United States)

    Heller, René

    2015-01-01

    Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  14. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  15. How Big is Earth?

    Science.gov (United States)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  16. Sulfur in Earth's Mantle and Its Behavior During Core Formation

    Science.gov (United States)

    Chabot, Nancy L.; Righter,Kevin

    2006-01-01

    The density of Earth's outer core requires that about 5-10% of the outer core be composed of elements lighter than Fe-Ni; proposed choices for the "light element" component of Earth's core include H, C, O, Si, S, and combinations of these elements [e.g. 1]. Though samples of Earth's core are not available, mantle samples contain elemental signatures left behind from the formation of Earth's core. The abundances of siderophile (metal-loving) elements in Earth's mantle have been used to gain insight into the early accretion and differentiation history of Earth, the process by which the core and mantle formed, and the composition of the core [e.g. 2-4]. Similarly, the abundance of potential light elements in Earth's mantle could also provide constraints on Earth's evolution and core composition. The S abundance in Earth's mantle is 250 ( 50) ppm [5]. It has been suggested that 250 ppm S is too high to be due to equilibrium core formation in a high pressure, high temperature magma ocean on early Earth and that the addition of S to the mantle from the subsequent accretion of a late veneer is consequently required [6]. However, this earlier work of Li and Agee [6] did not parameterize the metalsilicate partitioning behavior of S as a function of thermodynamic variables, limiting the different pressure and temperature conditions during core formation that could be explored. Here, the question of explaining the mantle abundance of S is revisited, through parameterizing existing metal-silicate partitioning data for S and applying the parameterization to core formation in Earth.

  17. 31 CFR 26.3 - Availability of Environmental Impact Assessment Summaries (EIA Summaries) and Environmental...

    Science.gov (United States)

    2010-07-01

    ... 31 Money and Finance: Treasury 1 2010-07-01 2010-07-01 false Availability of Environmental Impact Assessment Summaries (EIA Summaries) and Environmental Impact Assessments (EIAs). 26.3 Section 26.3 Money and... DEVELOPMENT BANDS (MDBs) § 26.3 Availability of Environmental Impact Assessment Summaries (EIA Summaries) and...

  18. Alkaline earth metal thioindates

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov-Ehmin, B.N.; Ivlieva, V.I.; Filatenko, L.A.; Zajtsev, B.E.; Kaziev, G.Z.; Sarabiya, M.G.

    1984-08-01

    Alkaline earth metal thioindates of MIn/sub 2/S/sub 4/ composition were synthesized by interaction of alkaline earth metal oxoindates with hydrogen sulfide during heating. Investigation into the compounds by X-ray analysis showed that calcium compound crystallizes in cubic crystal system and strontium and barium compounds in rhombic crystal system. Lattice parameters and the number of formula units were determined. Thioindates of M/sub 3/In/sub 2/S/sub 6/ composition were synthesized, their individuality was shown.

  19. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  20. Teaching earth science

    Science.gov (United States)

    Alpha, Tau Rho; Diggles, M.F.

    1998-01-01

    This CD-ROM contains 17 teaching tools: 16 interactive HyperCard 'stacks' and a printable model. They are separated into the following categories: Geologic Processes, Earthquakes and Faulting, and Map Projections and Globes. A 'navigation' stack, Earth Science, is provided as a 'launching' place from which to access all of the other stacks. You can also open the HyperCard Stacks folder and launch any of the 16 stacks yourself. In addition, a 17th tool, Earth and Tectonic Globes, is provided as a printable document. Each of the tools can be copied onto a 1.4-MB floppy disk and distributed freely.

  1. Quantizing Earth surface deformations

    Directory of Open Access Journals (Sweden)

    C. O. Bowin

    2015-03-01

    Full Text Available The global analysis of Bowin (2010 used the global 14 absolute Euler pole set (62 Myr history from Gripp and Gordon (1990 and demonstrated that plate tectonics conserves angular momentum. We herein extend that analysis using the more detailed Bird (2003 52 present-day Euler pole set (relative to a fixed Pacific plate for the Earth's surface, after conversion to absolute Euler poles. Additionally, new analytical results now provide new details on upper mantle mass anomalies in the outer 200 km of the Earth, as well as an initial quantizing of surface deformations.

  2. IR and the Earth

    DEFF Research Database (Denmark)

    Corry, Olaf; Stevenson, Hayley

    2017-01-01

    , in the end, one finite interconnected space. Together these two starting points make for the basic conundrum of Inter- national Relations and the Earth: how does a divided world live on a single globe? This introduction first provides an overview of the recent rise of ‘the environment’ in international......, ‘what has the environment ever done for IR?’, before the plan for the rest of the book sketches the content and direction of the ensuing chapters that explore the problematique of International Relations and the Earth....

  3. Indexing, screening, coding and cataloging of earth resources aircraft mission data

    Science.gov (United States)

    1977-01-01

    Tasks completed are as follows: (1) preparation of large Area Crop Inventory experiment for data base entry;(2) preparation of Earth Observations Aircraft Flight summary reports for publication; (3) updating of the aircraft mission index coverage map and Ames aircraft flight map; (4) Prepared of Earth Observation Helicopter Flight reports for publication; and (5) indexing of LANDSAT imagery. (6) formulation of phase 3 biowindows 1, 2, 3, and 4 listings by country, footprint, and acqusition dates; (7) preparation of flight summary reports; and (8) preparation of an Alaska state index coverage map.

  4. Crew Earth Observations: Twelve Years of Documenting Earth from the International Space Station

    Science.gov (United States)

    Evans, Cynthia A.; Stefanov, William L.; Willis, Kimberley; Runco, Susan; Wilkinson, M. Justin; Dawson, Melissa; Trenchard, Michael

    2012-01-01

    The Crew Earth Observations (CEO) payload was one of the initial experiments aboard the International Space Station, and has been continuously collecting data about the Earth since Expedition 1. The design of the experiment is simple: using state-of-the-art camera equipment, astronauts collect imagery of the Earth's surface over defined regions of scientific interest and also document dynamic events such as storms systems, floods, wild fires and volcanic eruptions. To date, CEO has provided roughly 600,000 images of Earth, capturing views of features and processes on land, the oceans, and the atmosphere. CEO data are less rigorously constrained than other remote sensing data, but the volume of data, and the unique attributes of the imagery provide a rich and understandable view of the Earth that is difficult to achieve from the classic remote sensing platforms. In addition, the length-of-record of the imagery dataset, especially when combined with astronaut photography from other NASA and Russian missions starting in the early 1960s, provides a valuable record of changes on the surface of the Earth over 50 years. This time period coincides with the rapid growth of human settlements and human infrastructure.

  5. Policy Document on Earth Observation for Urban Planning and Management: State of the Art and Recommendations for Application of Earth Observation in Urban Planning

    Science.gov (United States)

    Nichol, Janet; King, Bruce; Xiaoli, Ding; Dowman, Ian; Quattrochi, Dale; Ehlers, Manfred

    2007-01-01

    A policy document on earth observation for urban planning and management resulting from a workshop held in Hong Kong in November 2006 is presented. The aim of the workshop was to provide a forum for researchers and scientists specializing in earth observation to interact with practitioners working in different aspects of city planning, in a complex and dynamic city, Hong Kong. A summary of the current state of the art, limitations, and recommendations for the use of earth observation in urban areas is presented here as a policy document.

  6. Bones of the Earth

    Science.gov (United States)

    Correa, Jose Miguel

    2014-01-01

    The film "Bones of the Earth" (Riglin, Cunninham & Correa, 2014) is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective…

  7. Earth as art 4

    Science.gov (United States)

    ,

    2016-03-29

    Landsat 8 is the latest addition to the long-running series of Earth-observing satellites in the Landsat program that began in 1972. The images featured in this fourth installment of the Earth As Art collection were all acquired by Landsat 8. They show our planet’s diverse landscapes with remarkable clarity.Landsat satellites see the Earth as no human can. Not only do they acquire images from the vantage point of space, but their sensors record infrared as well as visible wavelengths of light. The resulting images often reveal “hidden” details of the Earth’s land surface, making them invaluable for scientific research.As with previous Earth As Art exhibits, these Landsat images were selected solely for their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation—only for your viewing pleasure. What do you see in these unique glimpses of the Earth’s continents, islands, and coastlines?

  8. DIORAMA Earth Terrain Model

    Energy Technology Data Exchange (ETDEWEB)

    Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-10

    When simulating near-surface nuclear detonations, the terrain of the Earth can have an effect on the observed outputs. The critical parameter is called the “height of burst”. In order to model the effect of terrain on the simulations we have incorporated data from multiple sources to give 9 km resolution data with global coverage.

  9. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.;

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  10. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  11. Understanding Earth's Albedo Effect

    Science.gov (United States)

    Fidler, Chuck

    2012-01-01

    Earth and space science in the middle school classroom are composed of intricately intertwined sets of conceptual systems (AAAS 1993; NRC 1996). Some systems of study, such as the water and rock cycles, are quite explicit and often found as stand-alone middle school science units. Other phenomena are not so apparent, yet they play an extremely…

  12. Olympus and Earth Day

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Let your gaze rest upon the poster for Earth Day on April 22. A small polar bear clings tightly to the stem of an aero-vane. Staring at the vanishing floating ice on the wild sea, his eyes are full of panic and fear.

  13. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  14. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Rare earth market continued drop tendency.There was not much transaction of didymium oxide and the alloy. Affected by reduced order of NdFeB magnetic materials and inactive dealings of didymium mischmetal,price of didymium mischmetal had dropped from RMB ¥95,000~98,000/ton to RMBY 93,000~95,000/ton currently.

  15. Cosmic rays on earth

    Energy Technology Data Exchange (ETDEWEB)

    Allkofer, O.C.; Grieder, P.K.F.

    1984-01-01

    A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted.

  16. "Galileo Calling Earth..."

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)

  17. Earth flyby anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LAB.

    2009-01-01

    In the planet-centric system, a spacecraft should have the same initial and final energies, even though its energy and angular momentum will change in the barycenter of the solar system. However, without explanation, a number of earth flybys have yielded small energy changes.

  18. Protect the Earth

    Institute of Scientific and Technical Information of China (English)

    张永兴

    2011-01-01

    The earth, a blue globe, is very beautiful. It is the home to all the living things. But the environment around us is becoming worse and worse. People cut down trees to build houses and throw about litter. The air pollution is almost everywhere in the world!

  19. Citizens of Planet Earth

    DEFF Research Database (Denmark)

    Frisk, Kristian

    2015-01-01

    The inability of the nation-state system to handle contemporary environmental issues comprehensively has spurred greater cooperation between religious and secular civil society actors. An empirical analysis of the Alliance of Religions and Conservation (ARC) contributes to knowledge about this pr...... (2010a) have termed Terrapolitan Earth Religion....

  20. Fusion Plasma Theory project summaries

    Energy Technology Data Exchange (ETDEWEB)

    1993-10-01

    This Project Summary book is a published compilation consisting of short descriptions of each project supported by the Fusion Plasma Theory and Computing Group of the Advanced Physics and Technology Division of the Department of Energy, Office of Fusion Energy. The summaries contained in this volume were written by the individual contractors with minimal editing by the Office of Fusion Energy. Previous summaries were published in February of 1982 and December of 1987. The Plasma Theory program is responsible for the development of concepts and models that describe and predict the behavior of a magnetically confined plasma. Emphasis is given to the modelling and understanding of the processes controlling transport of energy and particles in a toroidal plasma and supporting the design of the International Thermonuclear Experimental Reactor (ITER). A tokamak transport initiative was begun in 1989 to improve understanding of how energy and particles are lost from the plasma by mechanisms that transport them across field lines. The Plasma Theory program has actively-participated in this initiative. Recently, increased attention has been given to issues of importance to the proposed Tokamak Physics Experiment (TPX). Particular attention has been paid to containment and thermalization of fast alpha particles produced in a burning fusion plasma as well as control of sawteeth, current drive, impurity control, and design of improved auxiliary heating. In addition, general models of plasma behavior are developed from physics features common to different confinement geometries. This work uses both analytical and numerical techniques. The Fusion Theory program supports research projects at US government laboratories, universities and industrial contractors. Its support of theoretical work at universities contributes to the office of Fusion Energy mission of training scientific manpower for the US Fusion Energy Program.

  1. Plutonium focus area: Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-03-01

    To ensure research and development programs focus on the most pressing environmental restoration and waste management problems at the U.S. Department of Energy (DOE), the Assistant Secretary for the Office of Environmental Management (EM) established a working group in August 1993 to implement a new approach to research and technology development. As part of this approach, EM developed a management structure and principles that led to creation of specific focus areas. These organizations were designed to focus scientific and technical talent throughout DOE and the national scientific community on major environmental restoration and waste management problems facing DOE. The focus area approach provides the framework for inter-site cooperation and leveraging of resources on common problems. After the original establishment of five major focus areas within the Office of Technology Development (EM-50), the Nuclear Materials Stabilization Task Group (NMSTG, EM-66) followed EM-50`s structure and chartered the Plutonium Focus Area (PFA). NMSTG`s charter to the PFA, described in detail later in this book, plays a major role in meeting the EM-66 commitments to the Defense Nuclear Facilities Safety Board (DNFSB). The PFA is a new program for FY96 and as such, the primary focus of revision 0 of this Technology Summary is an introduction to the Focus Area; its history, development, and management structure, including summaries of selected technologies being developed. Revision 1 to the Plutonium Focus Area Technology Summary is slated to include details on all technologies being developed, and is currently planned for release in August 1996. The following report outlines the scope and mission of the Office of Environmental Management, EM-60, and EM-66 organizations as related to the PFA organizational structure.

  2. Whole-Earth Decompression Dynamics

    CERN Document Server

    Herndon, J M

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The initial whole-Earth decompression is expected to result in a global system of major primary decompression cracks appearing in the rigid crust which persist as the basalt feeders for the global, mid-oceanic ridge system. As the Earth subsequently decompresses, the area of the Earth's surface increases by the formation of secondary decompression cracks, often located near the continental margins, presently identified as oceanic trenches. These secondary decompression cracks are subsequently in-filled with basalt, extruded fr...

  3. Advanced fusion concepts: project summaries

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-12-01

    This report contains descriptions of the activities of all the projects supported by the Advanced Fusion Concepts Branch of the Office of Fusion Energy, US Department of Energy. These descriptions are project summaries of each of the individual projects, and contain the following: title, principle investigators, funding levels, purpose, approach, progress, plans, milestones, graduate students, graduates, other professional staff, and recent publications. Information is given for each of the following programs: (1) reverse-field pinch, (2) compact toroid, (3) alternate fuel/multipoles, (4) stellarator/torsatron, (5) linear magnetic fusion, (6) liners, and (7) Tormac. (MOW)

  4. Theory Summary {\\large (a Perspective}

    CERN Document Server

    Hou, George W -S

    2012-01-01

    This is the Theory Summary of the "Flavor Physics and CP Violation 2012" conference, with emphasis on New Physics. Besides covering the theory part of the conference, we pay attention also to the physics highlights of experimental talks. I then give my perspective on the false "Godot sightings" of the past decade, with some firsthand accounts. With all coming to naught (well, SM) at the moment, I look ahead to the near future, and to 2015 and beyond. An Epilogue is added with the advent of "the Higgs" at the LHC.

  5. Summary inside IBM's historic turnaround

    CERN Document Server

    2014-01-01

    This work offers a summary of the book "WHO SAYS ELEPHANTS CAN'T DANCE? Inside IBM's Historic Turnaround" by Louis Gerstner.In nine years as the chairman and CEO of International Business Machine Corporation (IBM), Louis Gerstner brought about a dramatic change in the company's fortunes. When he took charge, IBM was on the verge of extinction as the victim of rapid changes in the computer industry. However, instead of breaking up IBM as most analysts were suggesting, Gerstner and his management team turned the company around and restored it to a position of power and influence within the indu

  6. National stakeholder workshop summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-06-01

    This is a summary of the plenary sessions and small group discussion sessions from the fourth National Stakeholder Workshop sponsored by the DOE Office of Worker and Community Transition held in Atlanta, Georgia on March 13--15, 1996. Topics of the sessions included work force planning and restructuring, worker participation in health and safety, review of actions and commitments, lessons learned in collective bargaining agreements, work force restructuring guidance, work force planning, update on community transition activities. Also included are appendices listing the participants and DOE contacts.

  7. Summary of the Accelerator Meeting

    Energy Technology Data Exchange (ETDEWEB)

    Lia Merminga

    2006-07-17

    The summary of the paper is: (1) A compelling scientific case is developing for a high luminosity, polarized electron-ion collider, to address fundamental questions in hadron Physics. (2) Much progress over the past years: Design concepts are maturing through innovation and design optimization. (3) Electron cooling is prerequisite for all EIC design scenarios. A rigorous electron cooling R&D program established at BNL. (4) Important to continue collaboration and cross-fertilization of ideas among different design options. (5) Thank you to all the speakers for outstanding and thought-provoking presentations.

  8. Komatiites: From Earth's Geological Settings to Planetary and Astrobiological Contexts

    OpenAIRE

    Nna-Mvondo, Delphine; Martinez-Frias, Jesus

    2005-01-01

    Komatiites are fascinating volcanic rocks. They are among the most ancient lavas of the Earth following the 3.8 Ga pillow basalts at Isua and they represent some of the oldest ultramafic magmatic rocks preserved in the Earth's crust at 3.5 Ga. This fact, linked to their particular features (high magnesium content, high melting temperatures, low dynamic viscosities, etc.), has attracted the community of geoscientists since their discovery in the early sixties, who have tried to determine their...

  9. Geochemical Constraints on Core Formation in the Earth

    Science.gov (United States)

    Jones, John H.; Drake, Michael J.

    1986-01-01

    New experimental data on the partitioning of siderophile and chalcophile elements among metallic and silicate phases may be used to constrain hypotheses of core formation in the Earth. Three current hypotheses can explain gross features of mantle geochemistry, but none predicts siderophile and chalcophile element abundances to within a factor of two of observed values. Either our understanding of metal-silicate interactions and/or our understanding of the early Earth requires revision.

  10. The Earth's Biosphere

    Science.gov (United States)

    2002-01-01

    In the last five years, scientists have been able to monitor our changing planet in ways never before possible. The Sea-viewing Wide Field-of-View Sensor (SeaWiFS), aboard the OrbView-2 satellite, has given researchers an unprecedented view of the biological engine that drives life on Earth-the countless forms of plants that cover the land and fill the oceans. 'There is no question the Earth is changing. SeaWiFS has enabled us, for the first time, to monitor the biological consequences of that change-to see how the things we do, as well as natural variability, affect the Earth's ability to support life,' said Gene Carl Feldman, SeaWiFS project manager at NASA's Goddard Space Flight Center, Greenbelt, Md. SeaWiFS data, based on continuous daily global observations, have helped scientists make a more accurate assessment of the oceans' role in the global carbon cycle. The data provide a key parameter in a number of ecological and environmental studies as well as global climate-change modeling. The images of the Earth's changing land, ocean and atmosphere from SeaWiFS have documented many previously unrecognized phenomena. The image above shows the global biosphere from June 2002 measured by SeaWiFS. Data in the oceans is chlorophyll concentration, a measure of the amount of phytoplankton (microscopic plants) living in the ocean. On land SeaWiFS measures Normalized Difference Vegetation Index, an indication of the density of plant growth. For more information and images, read: SeaWiFS Sensor Marks Five Years Documenting Earth'S Dynamic Biosphere Image courtesy SeaWiFS project and copyright Orbimage.

  11. Isotopic evidence of Cr partitioning into Earth's core.

    Science.gov (United States)

    Moynier, Frederic; Yin, Qing-Zhu; Schauble, Edwin

    2011-03-18

    The distribution of chemical elements in primitive meteorites (chondrites), as building blocks of terrestrial planets, provides insight into the formation and early differentiation of Earth. The processes that resulted in the depletion of some elements [such as chromium (Cr)] in the bulk silicate Earth relative to chondrites, however, remain debated between leading candidate causes: volatility versus core partitioning. We show through high-precision measurements of Cr stable isotopes in a range of meteorites, which deviate by up to ~0.4 per mil from those of the bulk silicate Earth, that Cr depletion resulted from its partitioning into Earth's core, with a preferential enrichment in light isotopes. Ab initio calculations suggest that the isotopic signature was established at mid-mantle magma ocean depth as Earth accreted planetary embryos and progressively became more oxidized.

  12. Deriving Earth Science Data Analytics Requirements

    Science.gov (United States)

    Kempler, Steven J.

    2015-01-01

    Data Analytics applications have made successful strides in the business world where co-analyzing extremely large sets of independent variables have proven profitable. Today, most data analytics tools and techniques, sometimes applicable to Earth science, have targeted the business industry. In fact, the literature is nearly absent of discussion about Earth science data analytics. Earth science data analytics (ESDA) is the process of examining large amounts of data from a variety of sources to uncover hidden patterns, unknown correlations, and other useful information. ESDA is most often applied to data preparation, data reduction, and data analysis. Co-analysis of increasing number and volume of Earth science data has become more prevalent ushered by the plethora of Earth science data sources generated by US programs, international programs, field experiments, ground stations, and citizen scientists.Through work associated with the Earth Science Information Partners (ESIP) Federation, ESDA types have been defined in terms of data analytics end goals. Goals of which are very different than those in business, requiring different tools and techniques. A sampling of use cases have been collected and analyzed in terms of data analytics end goal types, volume, specialized processing, and other attributes. The goal of collecting these use cases is to be able to better understand and specify requirements for data analytics tools and techniques yet to be implemented. This presentation will describe the attributes and preliminary findings of ESDA use cases, as well as provide early analysis of data analytics toolstechniques requirements that would support specific ESDA type goals. Representative existing data analytics toolstechniques relevant to ESDA will also be addressed.

  13. Plutonium focus area. Technology summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    The Assistant Secretary for the Office of Environmental Management (EM) at the U.S. Department of Energy (DOE) chartered the Plutonium Focus Area (PFA) in October 1995. The PFA {open_quotes}...provides for peer and technical reviews of research and development in plutonium stabilization activities...{close_quotes} In addition, the PFA identifies and develops relevant research and technology. The purpose of this document is to focus attention on the requirements used to develop research and technology for stabilization, storage, and preparation for disposition of nuclear materials. The PFA Technology Summary presents the approach the PFA uses to identify, recommend, and review research. It lists research requirements, research being conducted, and gaps where research is needed. It also summarizes research performed by the PFA in the traditional research summary format. This document encourages researchers and commercial enterprises to do business with PFA by submitting research proposals or {open_quotes}white papers.{close_quotes} In addition, it suggests ways to increase the likelihood that PFA will recommend proposed research to the Nuclear Materials Stabilization Task Group (NMSTG) of DOE.

  14. Summary of LOGDEX data base

    Energy Technology Data Exchange (ETDEWEB)

    Hill, T.; Sepehrnoori, K.

    1981-08-01

    A summary of LOGDEX, the digitized well log data base maintained by the Center for Energy Studies at The University of Texas at Austin is presented. These well logs were obtained from various oil companies and then converted from paper well logs to numeric information on magnetic computer tapes for input into the well log data base. This data base serves as a resource for application programs in the study of geopressured geothermal energy resources, for well logging research, and for geological research. Currently the location and scope of well log data that may be found within the LOGDEX data base are limited to wells along the Texas-Louisiana Gulf Coast that are known to have a potential as a geopressured geothermal energy resource. Additionally the location of these wells in that area is highly localized into areas that have been defined by Department of Energy researchers as having a high potential for geopressured geothermal energy. The LOGDEX data base currently contains data from more than 350 wells, representing more than 1600 logs and 16,600,000 curve feet of data. For quick reference to a given log, the summary listing has been indexed into seven divisions: well classification, location by county or parish, curve type, log type, operators, location by state, and well names. These indexes are arranged alphabetically and cross-referenced by page number.

  15. DECOVALEX II PROJECT Executive Summary

    Energy Technology Data Exchange (ETDEWEB)

    Jing, L.; Stephansson, O. [Royal Inst. of Tech., Stockholm (Sweden). Dept. of Civil and Environmental Engineering; Tsang, C.F. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States). Earth Science Div.; Knight, L.J. [United Kingdom Nirex Ltd., Harwell (United Kingdom); Kautsky, F. [Swedish Nuclear Power Inspectorate (SKI), Stockholm (Sweden)

    1999-11-01

    DECOVALEX II project started in November 1995 as a continuation of the DECOVALEX I project, which was completed at the end of 1994. The project was initiated by recognising the fact that a proper evaluation of the current capacities of numerical modelling of the coupled T-H-M processes in fractured media is needed not only for small scale, well controlled laboratory test cases such as those studied in DECOVALEX I, but also for less characterised, more complex and realistic in-situ experiments. This executive summary presents the motivation, structure, objectives, approaches, and highlights of the main tasks and main achievements of the DECOVALEX II project from 1995-1999. The main source of the materials came from four technical reports the project prepared by the project Secretariat, which, in turn, were based on numerous progress reports produced by a large number of international research teams over the three and half year period. The editors of this summary, together with the Steering Committee of the DECOVALEX II project, feel very encouraged by the progresses which have been made during the project time and very positive about the usefulness of the achievements reached by the project to the larger international community of scientific research and management of radioactive wastes in different countries. We sincerely hope that continued efforts be made to forward the research carried out in both DECOVALEX I and DECOVALEX II projects so that the disposal of radioactive waste could be managed on a more reliable scientific basis.

  16. EarthScope Education and Outreach: Accomplishments and Emerging Opportunities

    Science.gov (United States)

    Robinson, S.; Ellins, K. K.; Semken, S. C.; Arrowsmith, R.

    2014-12-01

    EarthScope's Education and Outreach (E&O) program aims to increase public awareness of Earth science and enhance geoscience education at the K-12 and college level. The program is distinctive among major geoscience programs in two ways. First, planning for education and public engagement occurred in tandem with planning for the science mission. Second, the NSF EarthScope program includes funding support for education and outreach. In this presentation, we highlight key examples of the program's accomplishments and identify emerging E&O opportunities. E&O efforts have been collaboratively led by the EarthScope National Office (ESNO), IRIS, UNAVCO, the EarthScope Education and Outreach Subcommittee (EEOSC) and PI-driven EarthScope projects. Efforts by the EEOSC, guided by an EarthScope Education and Outreach Implementation Plan that is periodically updated, focus EarthScope E&O. EarthScope demonstrated early success in engaging undergraduate students (and teachers) in its mission through their involvement in siting USArray across the contiguous U.S. Funded E&O programs such as TOTLE, Illinois EarthScope, CEETEP (for K-12), InTeGrate and GETSI (for undergraduates) foster use of freely available EarthScope data and research findings. The Next Generation Science Standards, which stress science and engineering practices, offer an opportunity for alignment with existing EarthScope K-12 educational resources, and the EEOSC recommends focusing efforts on this task. The EEOSC recognizes the rapidly growing use of mobile smart devices by the public and in formal classrooms, which bring new opportunities to connect with the public and students. This will capitalize on EarthScope's already prominent social media presence, an effort that developed to accomplish one of the primary goals of the EarthScope E&O Implementation Plan to "Create a high-profile public identity for EarthScope" and to "Promote science literacy and understanding of EarthScope among all audiences through

  17. Earth: A Ringed Planet?

    Science.gov (United States)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  18. Rotation and magnetism of Earth`s inner core

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, G.A. [Los Alamos National Lab., NM (United States); Roberts, P.H. [Univ. of California, Los Angeles, CA (United States)

    1996-12-13

    Three-dimensional numerical simulations of the geodynamo suggest that a super-rotation of Earth`s solid inner core relative to the mantle is maintained by magnetic coupling between the inner core and an eastward thermal wind in the fluid outer core. This mechanism, which is analogous to a synchronous motor, also plays a fundamental role in the generation of Earth`s magnetic field. 18 refs., 6 figs.

  19. Earth Science Multimedia Theater

    Science.gov (United States)

    Hasler, A. F.

    1998-01-01

    The presentation will begin with the latest 1998 NASA Earth Science Vision for the next 25 years. A compilation of the 10 days of animations of Hurricane Georges which were supplied daily on NASA to Network television will be shown. NASA's visualizations of Hurricane Bonnie which appeared in the Sept 7 1998 issue of TIME magazine. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1 -min GOES images that will appear in the October BAMS. The visualizations are produced by the Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the "Digital-HyperRes-Panorama" Earth Science ETheater'98 recently presented in Tokyo, Paris and Phoenix. The presentation in Paris used a SGI/CRAY Onyx Infinite Reality Super Graphics Workstation at 2560 X 1024 resolution with dual synchronized video Epson 71 00 projectors on a 20ft wide screen. Earth Science Electronic Theater '999 is being prepared for a December 1 st showing at NASA HQ in Washington and January presentation at the AMS meetings in Dallas. The 1999 version of the Etheater will be triple wide with at resolution of 3840 X 1024 on a 60 ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense Hyperimage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites

  20. Visualizing Earth Materials

    Science.gov (United States)

    Cashman, K. V.; Rust, A.; Stibbon, E.; Harris, R.

    2016-12-01

    Earth materials are fundamental to art. They are pigments, they are clay, they provide form and color. Earth scientists, however, rarely attempt to make the physical properties of Earth materials visible through art, and similarly many artists use Earth materials without fully understanding their physical and chemical properties. Here we explore the intersection between art and science through study of the physical properties of Earth materials as characterized in the laboratory, and as transferred to paper using different techniques and suspending media. One focus of this collaboration is volcanic ash. Ash is interesting scientifically because its form provides information on the fundamental processes that drive volcanic eruptions, and determines its transport properties, and thus its potential to affect populations far downwind of the volcano. Ash properties also affect its behavior as an art material. From an aesthetic point of view, ash lends a granular surface to the image; it is also uncontrollable, and thus requires engagement between artist and medium. More fundamentally, using ash in art creates an exchange between the medium and the subject matter, and imparts something of the physical, visceral experience of volcanic landscapes to the viewer. Another component of this work uses powdered rock as a printing medium for geologic maps. Because different types of rock create powders with different properties (grain size distributions and shapes), the geology is communicated not only as color, but also by the physical characteristics of the material as it interacts with the paper. More importantly, the use of actual rocks samples as printing material for geologic maps not only makes a direct connection between the map and the material it represents, but also provides an emotional connection between the map, the viewer and the landscape, its colors, textures and geological juxtapositions. Both case studies provide examples not only of ways in which artists can

  1. Towards earth AntineutRino TomograpHy (EARTH)

    NARCIS (Netherlands)

    De Meijer, R. J.; Smit, F. D.; Brooks, F. D.; Fearick, R. W.; Wortche, H. J.; Mantovani, F.

    2006-01-01

    The programme Earth AntineutRino TomograpHy (EARTH) proposes to build ten underground facilities each hosting a telescope. Each telescope consists of many detector modules, to map the radiogenic heat sources deep in the interior of the Earth by utilising direction sensitive geoneutrino detection.

  2. Advanced energy projects FY 1997 research summaries

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-09-01

    The mission of the Advanced Energy Projects (AEP) program is to explore the scientific feasibility of novel energy-related concepts that are high risk, in terms of scientific feasibility, yet have a realistic potential for a high technological payoff. The concepts supported by the AEP are typically at an early stage of scientific development. They often arise from advances in basic research and are premature for consideration by applied research or technology development programs. Some are based on discoveries of new scientific phenomena or involve exploratory ideas that span multiple scientific and technical disciplines which do not fit into an existing DOE program area. In all cases, the objective is to support evaluation of the scientific or technical feasibility of the novel concepts involved. Following AEP support, it is expected that each concept will be sufficiently developed to attract further funding from other sources to realize its full potential. Projects that involve evolutionary research or technology development and demonstration are not supported by AEP. Furthermore, research projects more appropriate for another existing DOE research program are not encouraged. There were 65 projects in the AEP research portfolio during Fiscal Year 1997. Eigheen projects were initiated during that fiscal year. This document consists of short summaries of projects active in FY 1997. Further information of a specific project may be obtained by contacting the principal investigator.

  3. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ February, 2010 Rare earth separation plants and downstream producers like NdFeB magnetic materials and phosphor materials successively ceased production due to Spring Festival, Chinese New Year. Transactions in rare earth market were few affected by public holidays.

  4. Mirador - Earth Surface and Interior

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. The goal of the Earth Surface and Interior focus area is to assess, mitigate and forecast the natural hazards that affect...

  5. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Active demands from downstream industry drove the price rise of rare earth products in Chinese domestic marketrecently, particularly didymium and dysprosium products. Prices of other rare earth products remained stable.

  6. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market fluctuated slightly recently and the transactions remained sluggish. Environment control was strengthened in southern China and many rare earth plants had gone out of production. Some traders were considering selling commodities at low p

  7. NASA Benefits Earth

    Science.gov (United States)

    Robinson, Julie A.

    2009-01-01

    This slide presentation reviews several ways in which NASA research has benefited Earth and made life on Earth better. These innovations include: solar panels, recycled pavement, thermometer pill, invisible braces for straightening teeth, LASIK, aerodynamic helmets and tires for bicycles, cataract detection, technology that was used to remove Anthrax spores from mail handling facilities, study of atomic oxygen erosion of materials has informed the restoration of artwork, macroencapsulation (a potential mechanism to deliver anti cancer drugs to specific sites), and research on a salmonella vaccine. With research on the International Space Station just beginning, there will be opportunities for entrepreneurs and other government agencies to access space for their research and development. As well as NASA continuing its own research on human health and technology development.

  8. Life Before Earth

    CERN Document Server

    Sharov, Alexei A

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes. Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago. This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no...

  9. Testing MOND on Earth

    CERN Document Server

    Ignatiev, A Yu

    2014-01-01

    MOND is one of the most popular alternatives to Dark Matter (DM). While efforts to directly detect DM in laboratories have been steadily pursued over the years, the proposed Earth-based tests of MOND are still in their infancy. Some proposals recently appeared in the literature are briefly reviewed, and it is argued that collaborative efforts of theorists and experimenters are needed to move forward in this exciting new area. Possible future directions are outlined.

  10. Superhydrophobic diatomaceous earth

    Science.gov (United States)

    Simpson, John T [Clinton, TN; D& #x27; Urso, Brian R [Clinton, TN

    2012-07-10

    A superhydrophobic powder is prepared by coating diatomaceous earth (DE) with a hydrophobic coating on the particle surface such that the coating conforms to the topography of the DE particles. The hydrophobic coating can be a self assembly monolayer of a perfluorinated silane coupling agent. The DE is preferably natural-grade DE where organic impurities have been removed. The superhydrophobic powder can be applied as a suspension in a binder solution to a substrate to produce a superhydrophobic surface on the substrate.

  11. Why Earth aurorae shine?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ By using the data obtained from three satellites of the Cluster mission launched by the European Space Agency (ESA), CAO Jinbin from the CAS Center for Space Science and Applied Research (CSSAR) and his US and European co-workers have clarified why Earth's aurorae shine.Their work entitled Joint Observations by Cluster Satellites of Bursty Bulk Flows in the Magnetotail was published in a recent issue of Journal of Geophysical Research.

  12. Life Before Earth

    OpenAIRE

    Sharov, Alexei A; Gordon, Richard

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization,...

  13. Mission to Planet Earth

    Science.gov (United States)

    Tilford, Shelby G.; Wilson, Gregory S.; Backlund, Peter W.

    1991-01-01

    The NASA program described is an international study to predict changes in the earth's environment by means of multidisciplinary remote sensing from satellites. An international consortium dedicates satellites with advanced sensors to data collection, and a data processing system is described to collect and analyze a large amount of terrestrial data. The program requires international multidisciplinary involvement to collect and interpret the data and thereby manage and preserve the global environment.

  14. Earth Abides Arsenic Biotransformations

    OpenAIRE

    Zhu, Yong-Guan; Yoshinaga, Masafumi; Zhao, Fang-Jie; Rosen, Barry P.

    2014-01-01

    Arsenic is the most prevalent environmental toxic element and causes health problems throughout the world. The toxicity, mobility, and fate of arsenic in the environment are largely determined by its speciation, and arsenic speciation changes are driven, at least to some extent, by biological processes. In this article, biotransformation of arsenic is reviewed from the perspective of the formation of Earth and the evolution of life, and the connection between arsenic geochemistry and biology ...

  15. Earth before life

    OpenAIRE

    Marzban, Caren; Viswanathan, Raju; Yurtsever, Ulvi

    2014-01-01

    Background A recent study argued, based on data on functional genome size of major phyla, that there is evidence life may have originated significantly prior to the formation of the Earth. Results Here a more refined regression analysis is performed in which 1) measurement error is systematically taken into account, and 2) interval estimates (e.g., confidence or prediction intervals) are produced. It is shown that such models for which the interval estimate for the time origin of the genome i...

  16. Hunan Rare Earth Group Approved

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Following Guangdong,Guangxi,Fujian and Jiangxi,Hunan announced that it would consolidate its rare earth resources-the consolidation plan of Hunan Rare Earth Group has been approved. Consolidation of the rare earth industry of south China is in full swing.According to "Several Opinions of the State Council on Promoting the Sustainable and Healthy Development of Rare Earth Industry"(hereinafter referred to as "Several Opinions")released in 2011,

  17. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    September 20-30, 2011 Rare earth market remained steady recently. Quoted prices of didymium products by separation and smelting plants kept stable. Some rare earth industrial zones in Baotou, Sichuan and Ganzhou had suspended production with the intensified environmental protection control and consolidation of rare earth industry. Persons in the industry hold a positive attitude toward the rare earth market after the National Day' s holiday in China. The market will develop healthily and orderly in the future.

  18. Characterising Super-Earths

    Directory of Open Access Journals (Sweden)

    Valencia D.

    2011-02-01

    Full Text Available The era of Super-Earths has formally begun with the detection of transiting low-mass exoplanets CoRoT-7b and GJ 1214b. In the path of characterising super-Earths, the first step is to infer their composition. While the discovery data for CoRoT-7b, in combination with the high atmospheric mass loss rate inferred from the high insolation, suggested that it was a rocky planet, the new proposed mass values have widened the possibilities. The combined mass range 1−10 M⊕ allows for a volatile-rich (and requires it if the mass is less than 4 M⊕ , an Earth-like or a super-Mercury-like composition. In contrast, the radius of GJ 1214b is too large to admit a solid composition, thus it necessarily to have a substantial gas layer. Some evidence suggests that within this gas layer H/He is a small but non-negligible component. These two planets are the first of many transiting low-mass exoplanets expected to be detected and they exemplify the limitations faced when inferring composition, which come from the degenerate character of the problem and the large error bars in the data.

  19. EARTH ROADS ARE EASY

    Directory of Open Access Journals (Sweden)

    David O. Whitten

    2000-01-01

    Full Text Available The earliest European immigrants in America traveled on waterways and on pathways worn into the earth by animals and Native Americans. Once their communities began to thrive, settlers widened paths and cleared new roads and streets then began experimenting with inexpensive surfacing to reduce dust in dry weather and mud in wet. “Earth Roads Are Easy” investigates materials and techniques used to maintain primitive thoroughfares with a minimum of effort and expense. The options range from the mundane—clay, sand, gravel, calcium chloride, oil, and tar—to the extraordinary—water glass, adobe clay, beet juice, and carpeting.There is no more dfficult problem confronting highway engineers than that of properly constructing and maintaining an earth road. The work may be less spectacular than the construction and maintenance of hard-surfaced roads, but there is greater latitude in location, methods of construction and choice of materials, consequently there is more scope for the exercise of sound judgment on the part of the engineer.1

  20. The Active Solid Earth

    Science.gov (United States)

    Ebinger, Cynthia

    2016-04-01

    Dynamic processes in Earth's crust, mantle and core shape Earth's surface and magnetic field over time scales of seconds to millennia, and even longer time scales as recorded in the ca. 4 Ga rock record. Our focus is the earthquake-volcano deformation cycles that occur over human time scales, and their comparison with time-averaged deformation studies, with emphasis on mantle plume provinces where magma and volatile release and vertical tectonics are readily detectable. Active deformation processes at continental and oceanic rift and back arc zones provide critical constraints on mantle dynamics, the role of fluids (volatiles, magma, water), and plate rheology. For example, recent studies of the East African rift zone, which formed above one of Earth's largest mantle upwellings reveal that magma production and volatile release rates are comparable to those of magmatic arcs, the archetypal zones of continental crustal creation. Finite-length faults achieve some plate deformation, but magma intrusion in the form of dikes accommodates extension in continental, back-arc, and oceanic rifts, and intrusion as sills causes permanent uplift that modulates the local time-space scales of earthquakes and volcanoes. Volatile release from magma intrusion may reduce fault friction and permeability, facilitating aseismic slip and creating magma pathways. We explore the implications of active deformation studies to models of the time-averaged structure of plume and extensional provinces in continental and oceanic plate settings.

  1. Earth System Monitoring, Introduction

    Science.gov (United States)

    Orcutt, John

    This section provides sensing and data collection methodologies, as well as an understanding of Earth's climate parameters and natural and man-made phenomena, to support a scientific assessment of the Earth system as a whole, and its response to natural and human-induced changes. The coverage ranges from climate change factors and extreme weather and fires to oil spill tracking and volcanic eruptions. This serves as a basis to enable improved prediction and response to climate change, weather, and natural hazards as well as dissemination of the data and conclusions. The data collection systems include satellite remote sensing, aerial surveys, and land- and ocean-based monitoring stations. Our objective in this treatise is to provide a significant portion of the scientific and engineering basis of Earth system monitoring and to provide this in 17 detailed articles or chapters written at a level for use by university students through practicing professionals. The reader is also directed to the closely related sections on Ecological Systems, Introduction and also Climate Change Modeling Methodology, Introduction as well as Climate Change Remediation, Introduction to. For ease of use by students, each article begins with a glossary of terms, while at an average length of 25 print pages each, sufficient detail is presented for use by professionals in government, universities, and industries. The chapters are individually summarized below.

  2. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  3. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  4. USACE AIS Transmit Technical Support Summary Report

    Science.gov (United States)

    2014-09-01

    USACE AIS Transmit Technical Support Summary Report Distribution Statement A: Approved for public release; distribution is unlimited...September 2014 Report No. CD-D-09-15 USACE AIS Transmit Technical Support Summary Report ii UNCLAS//Public | CG-926 RDC | I. Gonin et al. Public...States Coast Guard Research & Development Center 1 Chelsea Street New London, CT 06320 USACE AIS Transmit Technical Support Summary Report

  5. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Supply of rare earth concentrate remained tight recently. Rare earth market exhibited rising tendency holistically Affected by tight supply of rare earth concentrate, many plants were operated under the capacity. Supply of didymium oxide got tighter and the price was on rising.

  6. Summary of ISNP2K

    Indian Academy of Sciences (India)

    H Ejiri

    2001-08-01

    This is a brief summary of the ISNP2K (International Symposium on Nuclear Physics, 2000). Many interesting works were presented on new developments and perspectives of nuclear physics in the plenary and poster sessions. Subjects discussed are 1) high temperature and high density nuclei, new QGP phases and relativistic HI collisions, 2) new degrees of freedoms studied by medium energy reactions, 3) exotic nuclei with large isospin, large , high and high , 4) new dynamical properties of many body nucleon systems, 5) neutrino nuclear physics and neutrons for astroparticle physics, and 6) new accelerators and new applications. ISNP2K with extensive discussions on nuclear physics frontiers at the turning point from 2000 to 2001 provides a good bridge to the new century.

  7. AFIP-6 Characterization Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Dennis D. Keiser

    2011-12-01

    The AFIP-6 (ATR Full-size-plate In center flux trap Position) Characterization Summary Report outlines the fresh fuel characterization efforts performed during the AFIP-6 experiment. The AFIP-6 experiment was designed to evaluate the performance of monolithic uranium-molybdenum (U-Mo) fuels at a scale prototypic of Advanced Test Reactor (ATR) fuel plates (45-inches long). The AFIP-6 test was the first test with plates that were swaged into the rails of the assembly. This test served to examine the effects of a plate in a swaged condition with longer fuel zones (22.5-inches long), that were centered in the plate. AFIP-6 test plates employed a zirconium interlayer that was co-rolled with the fuel foil. Previous mini-plate and AFIP irradiation experiments performed in ATR have demonstrated the stable behavior of the interface between the U-Mo fuel and the zirconium interlayer.

  8. Strategy for earth explorers in global earth sciences

    Science.gov (United States)

    1988-01-01

    The goal of the current NASA Earth System Science initiative is to obtain a comprehensive scientific understanding of the Earth as an integrated, dynamic system. The centerpiece of the Earth System Science initiative will be a set of instruments carried on polar orbiting platforms under the Earth Observing System program. An Earth Explorer program can open new vistas in the earth sciences, encourage innovation, and solve critical scientific problems. Specific missions must be rigorously shaped by the demands and opportunities of high quality science and must complement the Earth Observing System and the Mission to Planet Earth. The committee believes that the proposed Earth Explorer program provides a substantial opportunity for progress in the earth sciences, both through independent missions and through missions designed to complement the large scale platforms and international research programs that represent important national commitments. The strategy presented is intended to help ensure the success of the Earth Explorer program as a vital stimulant to the study of the planet.

  9. Digital Earth - Young generation's comprehension and ideas

    Science.gov (United States)

    Bandrova, T.; Konecny, M.

    2014-02-01

    The authors are experienced in working with children and students in the field of early warning and crises management and cartography. All these topics are closely connected to Digital Earth (DE) ideas. On the basis of a questionnaire, the young generation's comprehension of DE concept is clarified. Students from different age groups (from 19 to 36) from different countries and with different social, cultural, economical and political backgrounds are asked to provide definition of DE and describe their basic ideas about meaning, methodology and applications of the concept. The questions aim to discover the young generation's comprehension of DE ideas. They partially cover the newest trends of DE development like social, cultural and environmental issues as well as the styles of new communications (Google Earth, Facebook, LinkedIn, etc.). In order to assure the future development of the DE science, it is important to take into account the young generation's expectations. Some aspects of DE development are considered in the Conclusions.

  10. Life and the evolution of Earth's atmosphere.

    Science.gov (United States)

    Kasting, James F; Siefert, Janet L

    2002-05-10

    Harvesting light to produce energy and oxygen (photosynthesis) is the signature of all land plants. This ability was co-opted from a precocious and ancient form of life known as cyanobacteria. Today these bacteria, as well as microscopic algae, supply oxygen to the atmosphere and churn out fixed nitrogen in Earth's vast oceans. Microorganisms may also have played a major role in atmosphere evolution before the rise of oxygen. Under the more dim light of a young sun cooler than today's, certain groups of anaerobic bacteria may have been pumping out large amounts of methane, thereby keeping the early climate warm and inviting. The evolution of Earth's atmosphere is linked tightly to the evolution of its biota.

  11. Charles M. Russell National Wildlife Range Wilderness proposal public hearing summary analysis and wilderness study summary

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document contains both a public hearing summary analysis and a wilderness study summary for the Charles M. Russell National Wildlife Range. The public hearing...

  12. Progress Developing the Kansas Early Childhood Special Education Accountability System: Initial Findings Using ECO and COSF

    Science.gov (United States)

    Greenwood, Charles R.; Walker, Dale; Hornbeck, Marguerite; Hebbeler, Kathleen; Spiker, Donna

    2007-01-01

    Policy decision makers, early educators, and early interventionists face numerous challenges as they develop and implement statewide accountability systems to evaluate and improve children's early intervention and early childhood special education outcomes. Kansas was an early adopter of the Child Outcomes Summary Form (COSF) developed by the…

  13. Primary Education Project. Program Summary.

    Science.gov (United States)

    Far West Lab. for Educational Research and Development, Berkeley, CA.

    This document is the last in a series of 12 early childhood program descriptions compiled by the Far West Laboratory for Educational Research and Development. The program described here is the Primary Education Project (PEP) developed at the Learning Research and Development Center of the University of Pittsburgh. The PEP project is concerned with…

  14. Summary of Green Building Programs

    Energy Technology Data Exchange (ETDEWEB)

    2002-08-01

    In early 2002, the National Association of Home Builders completed a census of residential green building programs across the United States to assess differences and similarities among programs. This report catalogs different ways that builders participate in residential green building programs.

  15. Sustainable early-career networks

    Science.gov (United States)

    Rauser, Florian; Schemann, Vera; Sonntag, Sebastian

    2015-10-01

    A truly global science community for the next generation of researchers will be essential if we are to tackle Earth system sustainability. Top-down support from funders should meet bottom-up initiatives -- at a pace fast enough to meet that of early-career progress.

  16. Bones of the Earth

    Directory of Open Access Journals (Sweden)

    Jose Miguel Correa

    2014-06-01

    Full Text Available The film Bones of the Earth (Riglin, Cunninham & Correa, 2014 is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective creation is built. A sense of community, on-going inquiry, connections and social commitment inform the creative process. As a result, the video’s nearly five intense minutes are a metaphor for the search for personal meaning, connection with nature and intersubjective positioning in a world that undergoes constant change.

  17. The earth's gravitational field

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    of the tides) have a very small effect on the apparent strength of Earth's gravity, depending on their relative positions; typical variations are 2 µm/s² (0.2 mGal) over the course of a day. Gravity measurements at sea The gravity measurements at sea... quoted as an acceleration, which in SI units is measured in m/s 2 (metres per second per second, equivalently written as m·s −2 ). It has an approximate value of 9.8 m/s 2 , which means that, ignoring air resistance, the speed of an object falling...

  18. Solid Earth: The priorities

    Science.gov (United States)

    Paquet, P.

    1991-10-01

    The European Space Agency's strategy concerning the solid Earth program is reviewed. Improvement of current knowledge of the global geopotential fields, both gravity and magnetic, was stressed as the highest priority. It was agreed that the objectives and goals of the planned Aristoteles mission correspond to this priority, and the need to realize this part of the program was stated. The interdisciplinary links of the program were identified, and it was decided that this program could make substantial contributions to research of oceans, climate and global change, atmosphere, ice and land surfaces.

  19. Detecting Terrorism Incidence Type from News Summary

    DEFF Research Database (Denmark)

    Nizamani, Sarwat; Memon, Nasrullah

    2012-01-01

    The paper presents the experiments to detect terrorism incidence type from news summary data. We have applied classification techniques on news summary data to analyze the incidence and detect the type of incidence. A number of experiments are conducted using various classification algorithms...

  20. Improving text recall with multiple summaries

    NARCIS (Netherlands)

    Meij, van der Hans; Meij, van der Jan

    2012-01-01

    Background. QuikScan (QS) is an innovative design that aims to improve accessibility, comprehensibility, and subsequent recall of expository text by means of frequent within-document summaries that are formatted as numbered list items. The numbers in the QS summaries correspond to numbers placed in