WorldWideScience

Sample records for cosmochemistry

  1. Archaeology, Artifacts, and Cosmochemistry

    Science.gov (United States)

    Martel, L. M. V.

    2017-06-01

    PSRD covers research that ascertains the content, formation, and evolution of our Solar System and planetary systems in general. Our archives are full of sample-based studies of extraterrestrial materials that relate to the building of planets, moons, and minor bodies. Rarely do we cover the cosmochemistry of artifacts, but the importance of cosmochemistry is abundantly clear in this story of artisan iron beads of archaeological significance and the quest to find the source meteorite. Twenty-two meteoritic iron beads, recovered from mounds in Havana, Illinois of the Hopewell people and culture, have been identified as pieces of the Anoka iron meteorite, according to work by Timothy McCoy (National Museum of Natural History, Smithsonian Institution), Amy Marquardt (undergraduate intern at the NMNH/SI and now at the University of Colorado at Boulder), John Wasson (UCLA), Richard Ash (University of Maryland), and Edward Vicenzi (SI).

  2. Radial Breathing Modes in Cosmochemistry and Meteoritics

    Science.gov (United States)

    Wilson, T.L.; Wilson, K.B.

    2009-01-01

    One area of continuing interest in cosmochemistry and meteoritics (C&M) is the identification of the nature of Q-phase, although some researchers in C&M are not reporting relevant portions of Raman spectral data. Q is the unidentified carrier of noble gases in carbonaceous chondrites (CCs). Being carbonaceous, the focus has been on any number of Q-candidates arising from the sp2 hybridization of carbon (C). These all derive from various forms of graphene, a monolayer of C atoms packed into a two-dimensional (2D) hexagonal honeycomb lattice that is the basic building block for graphitic materials of all other dimensions for sp2 allotropes of C. As a basic lattice, 2D graphene can be curled into fullerenes (0D), wrapped into carbon nanotubes or CNTs (1D), and stacked into graphite (3D). These take such additional forms as scroll-like carbon whiskers, carbon fibers, carbon onions, GPCs (graphite polyhedral crystals) [6], and GICs (graphite intercalation compounds). Although all of these have been observed in meteoritics, the issue is which can explain the Q-abundances. In brief, one or more of the 0D-3D sp2 hybridization forms of C is Q. For some Q-candidates, the radial breathing modes (RBMs) are the most important Raman active vibrational modes that exist, and bear a direct relevance to solving this puzzle. Typically in C&M they are ignored when present. Their importance is addressed here as smoking-gun signatures for certain Q-candidates and are very relevant to the ultimate identification of Q.

  3. Cosmochemistry Illustrated: Recruiting and Training the Next Generation of Cosmochemists

    Science.gov (United States)

    Taylor, J.; Martel, L.

    2010-12-01

    Ongoing and planned sample-return missions by the U.S. and other nations require that a strong cadre of specialists in the mineralogy, petrology, chemistry, and isotope chemistry of extraterrestrial materials is available to analyze these valuable samples. These fields are captured by the term cosmochemistry. To lure undergraduate and graduate students already interested in terrestrial geochemistry into cosmochemistry, I am creating a set of PowerPoint slides and related materials for use by college faculty members teaching geoscience courses. This effort, known as Cosmochemistry Illustrated, is funded by the Opportunities in SMD Education and Public Outreach program and is already hosted online at the Hawaii Institute of Geophysics and Planetology. Its goals are: (1) Increase the number of students studying cosmochemistry and related planetary geoscience topics. (2) Enhance the cosmochemical expertise of students studying planetary geology and geophysics, and astronomy and astrophysics. (3) Improve the effectiveness of cosmochemists in giving public presentations and courses for non-science majors by providing readily-accessible, up-to-date resources. In spite of cosmochemistry being a vibrant field, there is a shortage of people to work on the large number of meteorites we now have in our collections, the still-valuable lunar sample collection, interplanetary dust particles collected in the stratosphere, and samples returned by robotic missions (e.g., Stardust). Cosmochemists also contribute their expertise to interpreting data obtained by remote sensing and in situ analysis. They have been especially prominent in interpreting data from the Clementine and Lunar Prospector missions to the Moon, Mars orbital missions (especially Mars Global Surveyor and Mars Odyssey), and the landed Pathfinder and Mars Exploration Rover missions. We need enough scientists trained in cosmochemistry to continue to make full use of remote sensing data. The foundation of Cosmochemistry

  4. Invited review article: Recent developments in isotope-ratio mass spectrometry for geochemistry and cosmochemistry.

    Science.gov (United States)

    Ireland, Trevor R

    2013-01-01

    Mass spectrometry is fundamental to measurements of isotope ratios for applications in isotope geochemistry, geochronology, and cosmochemistry. Magnetic-sector mass spectrometers are most common because these provide the best precision in isotope ratio measurements. Where the highest precision is desired, chemical separation followed by mass spectrometric analysis is carried out with gas (noble gas and stable isotope mass spectrometry), liquid (inductively coupled plasma mass spectrometry), or solid (thermal ionization mass spectrometry) samples. Developments in in situ analysis, including ion microprobes and laser ablation inductively coupled plasma mass spectrometry, have opened up issues concerning homogeneity according to domain size, and allow ever smaller amounts of material to be analyzed. While mass spectrometry is built solidly on developments in the 20th century, there are new technologies that will push the limits in terms of precision, accuracy, and sample efficiency. Developments of new instruments based on time-of-flight mass spectrometers could open up the ultimate levels of sensitivity per sample atom.

  5. Extrasolar Cosmochemistry

    Science.gov (United States)

    Jura, M.; Young, E. D.

    2014-05-01

    Evidence is now compelling that elements heavier than helium in many white dwarf atmospheres have accumulated by accretion from orbiting rocky bodies, often larger than 100 km in diameter, such as asteroids. Consequently, we now possess a powerful tool to measure the elemental constituents of extrasolar minor planets. To zeroth order, the accreted extrasolar parent bodies resemble bulk Earth: They are at least 85% by mass composed of oxygen, magnesium, silicon, and iron; carbon and ice are only trace constituents. Assembled data for white dwarf pollutions suggest that differentiation of extrasolar planetesimals, leading to iron-rich cores and aluminum-rich crusts, is common. Except for instances of unexpectedly high calcium abundances, the compositions of extrasolar planetesimals can be understood as resulting from processes similar to those controlling the formation and evolution of objects in the inner Solar System.

  6. Research Progress in Meteoritics and Cosmochemistry(2001-2010)%陨石学与天体化学(2001~2010)研究进展

    Institute of Scientific and Technical Information of China (English)

    林杨挺; 缪秉魁; 徐琳; 胡森; 冯璐; 赵旭晁; 杨晶

    2013-01-01

    In the first 10 years of 21st century, meteoritics and cosmochemistry made significant progress in China. During 5 times of Chinese Antarctic Research Expeditions, more than 10 thousands of meteorites have been collected from Grove Mountain areas, supplying with precious extraterrestrial samples. The study of meteoritics and cosmochemistry has also been promoted by Chang'e mission and the great success in the first episode of Chinese lunar exploration, and is challenged by the demands of space exploration. Various high precision and high laterial resolution measurements of extraterrestrial samples are now available with a number of newly established facilities and e-quipments. Furthermore, many young researchers have been involved in cosmochemistry and trained via classifying the large number of Antarctic meteorites. By studying of various groups of meteorites, numerous discoveries have been made, inclusing presolar grains in primitive chondrites, short-lived radionuclides, condensation processes of the solar nebula under different redox conditions, petrogenesis and isotopic dating of lunar meteorites and martian meteorites, shock metamorphism and high pressure polymorphs in shocked meteorites, and confirmation of the first meteorite impact crater in China.%21世纪的第一个十年,陨石学与天体化学研究在中国迎来了一个前所未有的发展时期.在南极格罗夫山地区共开展了5次科学考察,收集到超过1万块陨石,提供了珍贵的研究样品;嫦娥工程的立项和一期工程的成功实施,是陨石学与天体化学发展的重大机遇,也是挑战;高精度原位微区分析平台建设的完成,则为地外物质样品的分析提供了关键的技术保证.更为重要的是,通过大量南极陨石的分类工作,培养和锻炼了陨石学研究的青年人才.在此基础上,通过对各化学群陨石的研究,取得了许多重要的成果,包括陨石中前太阳颗粒的发现和研究、陨石中的灭绝核

  7. 陨石学及天体化学研究某些新进展%Some Recent Advances in Meteoritics and Cosmochemistry

    Institute of Scientific and Technical Information of China (English)

    王道德; 王桂琴

    2012-01-01

    Meteorites usually derive from primitive materials that condensed and accreted from the gas-and dust-containing presolar disk.Most of them were altered by postaccretionary processes(as in lunar,terrestrial,and martian samples),but some survived essentially integrity(as chondrites or inclusions in chondrites).These primitive chondrites are recognizable usually from isotopic abundance characteristics.Based on mineral-petrologic characteristics and their origin we can classify known meteorites into a much smaller number of types.Recent advance in miteoritic and cosmochemistry include the newly recognized meteorite groups;discoveries about the presolar and nebular components of chondrites and interplanetary;improvements in early solar system chronology using short-radionuclides;new insights into cosmochemical abundances;fractionation,and nebular reservoirs;and advance explanation for nebular and prenebular records of secondary parent body processes.We summarized evolved process from nebula to meteorite in early solar system.Some new insights based on these data are that the early solar system experienced a variety of nucleosynthetic input,the dynamic entity with transient heating events,and the system of plantesimals and planets evolved more rapidly than previously expected.%陨石是来自含气体-尘粒的太阳早期星云盘凝聚和吸积的原始物质,大多数原始物质因吸积后的作用过程而改变(如月球、地球及火星样品),但有一些却完整的保存下来(如球粒陨石或球粒陨石中的难熔包体)。这些原始的物质通常依据同位素丰度特征来识别,依据其矿物-岩石学特征和成因可将已知的陨石划分许多更小的类型。陨石学及天体化学的新近进展包括:新近识别的陨石群;发现新类型球粒陨石及行星际尘粒中发现前太阳和星云组分;利用短寿命放射性核素完善了早期太阳系年代学;洞察宇宙化学丰度、分馏作用及星云源

  8. 激光剥蚀-等离子体质谱技术及其在地球化学宇宙化学和环境研究中的应用%Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry and Its Application in Geochemistry, Cosmochemistry and Environmental Research

    Institute of Scientific and Technical Information of China (English)

    JOCHUM Klaus Peter; KUZMIN Dmitry; MERTZ-KRAUS Regina; MüLLER Werner E G; REGNERY Julia; SOBOLEV Alexander; 王晓红; 詹秀春; STOLL Brigitte; FRIEDRICH Jon M; AMINI Marghaleray; BECKER Stefan; DüCKING Marc; EBEL Denton S; ENZWEILER Jacinta; HU Ming-yue

    2009-01-01

    激光剥蚀-等离子体质谱(LA-ICPMS)已成为地球化学、宇宙化学和环境研究领域元素和同位素原位分析最重要的技术之一.文章介绍了多种类型的质谱仪及其使用的激光器.用途最广的LA-ICPMS仪器之一是单接收器扇形磁场质谱仪,配有Nd:YAG激光剥蚀系统(激光波长分为193 nm和213 nm两种),MPI Mainz实验室使用的就是这套系统,文章对此作一详细介绍.文中阐述了数据优化技术及其多种校正过程;介绍LA-ICPMS在痕量元素和同位素分析领域的一些应用,包括参考物质的研制,Hawaiian玄武岩、Martian陨石、生物骨针和珊瑚虫中痕量元素分析及熔融包裹体和富钙-铝碳质球粒陨石中的铅和锶同位素测量.%Laser ablation (LA)-inductively coupled plasma-mass spectrometry (ICP-MS) has become one of the most important methods for in situ trace elemental and isotopic analysis in geochemistry, cosmochemistry and environmental research. For these purposes, different kinds of mass spectrometers and lasers are used, which are presented in this paper. One of the most useful LA-ICPMS instruments is the combination of a single-collector sector field mass spectrometer with Nd:YAG laser ablation systems (193 nm and 213 nm wavelengths, respectively). This design used in the MPI Mainz laboratory is described in detail in this paper. Data optimization techniques including diverse correction procedures are also discussed. To demonstrate the power of LA-ICPMS, several applications of trace elemental and isotopic analysis are presented, such as investigations of reference materials, trace element analysis in Hawaiian basalts, Martian meteorites, biological spicules and corals, as well as Pb and Sr isotope measurements of melt inclusions and Ca-Al rich inclusions of carbonaceous chondrites.

  9. Petrology and Cosmochemistry of a Suite of R Chondrites

    Science.gov (United States)

    Torrano, Z. A.; Mittlefehldt, D. W.; Peng, Z. X.

    2015-01-01

    Chondrites are among the most primitive surviving materials from the early solar system. They are divided into groups based on chemical types defined by mineralogy, bulk composition, and oxygen isotope compositions. Chondrites range in petrographic grade from type 1 to type 7. Type 3 chondrites are the most primitive and are little changed from the nebular solids accreted to form asteroids. They are composed of chondrules, fine-grained matrix, metal and sulfide, plus or minus Ca-Al-rich inclusions. With increasing aqueous alteration at low temperatures, members of some chondrite classes transformed from type 3 towards type 1. With increasing thermal metamorphism and low fluid content, members of other classes changed from type 3 towards type 7. Rumuruti (R) chondrites are a rare group (0.1% of falls) similar to ordinary chondrites in some properties but different in others. They are characterized by low chondrule/matrix modal abundance ratios, high oxidation state, small mean chondrule size, abundant sulfides and low metal contents. R chondrites vary in petrologic type from 3 to 6. They are important objects to study because some of them have undergone metamorphism at high temperatures in the presence of aqueous fluids. In contrast, CM and CI chondrites were heated to low temperatures in the presence of aqueous fluids leading to alteration; they contain low-T hydrous phases (phyllosilicates) and little or no remaining metal. Ordinary chondrites were heated to high temperatures in a low-fluid environment resulting in anhydrous metamorphic rocks. R6 chondrites are highly metamorphosed and some contain the high-T hydrous phases mica and amphibole. R chondrites are thus unique and give us an opportunity to examine whether there are compositional effects caused by high-T, highfluid metamorphism of nebular materials.

  10. Synthesis of Ti Oxides at Reducing Conditions: Implications for Beamline Standards and Cosmochemistry

    Science.gov (United States)

    Righter, K.; Pando, K. A.; Butterworth, A. L.; Gainsforth, Z.; Jilly-Rehak, C. E.; Westphal, A. J.

    2017-01-01

    These initial experiments demonstrate the great potential for synthesizing customized compounds for use as standards, or in buffering experiments at reducing conditions. We are also investigating Cr and V oxides, as well as compounds containing these elements such as FeV2O4 and FeCr2O4. Oxygen fugacity exerts a major control on mineral major element chemistry and elemental valence of minerals in any plane-tary compositional system [1]. For Earth, Fe is multivalent ranging from nearly Fe0 at low fO2 in the deep mantle to Fe2+ to Fe3+ at high low fO2. For solar nebular and meteoritic materials fO2 ranges from near IW to 10 log fO2 units below the IW buffer [1]. Phases in CAIs, for example, contain no Fe2+, but may contain Ti4+, Ti3+, or Ti2+, and Cr3+ or Cr2+, and V3+ or V2+ [1,2,3]. De-tailed study of inclusions may reveal important differences in fO2 thus reflecting different environments in the solar nebula [4]. XANES, FEG-SEM, and TEM can reveal such variations in micro and nano samples such as Stardust and cosmic dust particles [5], but successful application to reduced conditions depends upon the availability of well characterized standards. Acquiring appropriate standards for reduced phases that contain Ti3+ or Ti2+, Cr3+ or Cr2+, and V3+ or V2+ can be a challenge. Here we report our preliminary results at synthesizing reduced Ti bearing standards, and focus on the preliminary characterization.

  11. News and Views: Meetings of minds; Budgeting for the budget; Cosmochemistry at home in the UK

    Science.gov (United States)

    2009-06-01

    In a time of tight belts and political uncertainty in the UK, a budget settlement that does not decrease money awarded to science has to be a good step, but it is clear that the maintenance of funding announced last month has a price for the research councils. Extraterrestrial chemistry, a UK research strength, is now reinforcing community links through the Cosmochemical Analysis Network (CAN), which allows members access to world-class analytical facilities, enabling UK scientists to study extraterrestrial materials in all its forms and prepare for samples returned by future missions.

  12. Cosmochemistry, cosmology and fundamental constants: High-resolution spectroscopy of damped Lyman-alpha systems

    CERN Document Server

    Quast, R; Smette, A; Garcet, O; Ledoux, C; López, S; Wisotzki, L

    2004-01-01

    Spectroscopy of QSO absorption lines provides essential observational input for the study of nucleosynthesis and chemical evolution of galaxies at high redshift. But new observations may indicate that present chemical abundance data are biased due to deficient spectral resolution and unknown selection effects: Recent high-resolution spectra reveal the hitherto unperceived chemical nonuniformity of molecular hydrogen-bearing damped Lyman-alpha (DLA) systems, and the novel H/ESO DLA survey produces compelling evidence for faint QSOs being attenuated by dust. We present a revised analysis of the molecular hydrogen-bearing DLA complex toward HE 0515-4414 showing nonuniform differential depletion of chemical elements onto dust grains, and introduce to the H/ESO DLA survey and its implications. Conclusively, we aim at starting an unbiased chemical abundance database established on high-resolution spectroscopic observations. New data to probe the temperature-redshift relation predicted by standard cosmology and to t...

  13. Potassium isotope cosmochemistry, volatile depletion and the origin of the Earth

    Science.gov (United States)

    Humayun, M.; Clayton, R. N.

    1993-01-01

    We report the first results obtained by our techniques for the precise and accurate determination of the isotopic composition of potassium to constrain the mechanism of volatile element depletion in the formation of the Earth, Moon, and meteorites. Our measurements of delta(K-41) for six chondrites and ten terrestrial rocks attained an average precision of the individual measurement of plus or minus 0.4 percent (2 sigma; plus or minus 0.2 percent/a.m.u. and yield a net chondrite-Earth difference unresolved at the 99 percent confidence limit, delta(K-41) = 0.32 plus or minus 0.35 percent (3 delta). This sets a firm upper limit of 1.3 plus or minus 1.4 percent Rayleigh evaporation of terrestrial potassium (using alpha = square root of 41/39), compared with an observed approximately equals 85 percent chemical depletion of K relative to C1 chondrites. Similar conclusions are reached for the SNC meteorites, Shergotty and Zagami, for 15495 (lunar mare gabbro), and for the eucrite Juvinas. Our conclusion is that direct evaporation of volatile elements from planets (e.g. from silicate vapor atmospheres following giant impact) can be ruled out, and the cause of volatile loss must be sought elsewhere, e.g. nebular processes. Our present findings do not support the conclusions of Hinton et al., the discrepancy to be resolved at a later date. We also find lunar soil 64801, delta(K-41) = +4.99 plus or minus 0.53 percent, to be distinctly heavy in accord with Garner et al.

  14. Kodai School on ‘Synthesis of Elements in Stars’

    CERN Document Server

    Goswami, Aruna; Principles and Perspectives in Cosmochemistry

    2010-01-01

    A fundamental question in contemporary astrophysics is the origin of the elements. Cosmochemistry seeks to answer when, how and where the chemical elements arose. Quantitative answers to these fundamental questions require a multi-disciplinary approach involving stellar evolution, explosive nucleosynthesis and nuclear reactions in different astrophysical environments. There remain, however, many outstanding problems and cosmochemistry remains a fertile area of research. This book is among the first in recent times to put together the essentials of cosmochemistry, combining contributions from leading astrophysicists in the field. The chapters have been organized to provide a clear description of the fundamentals, an introduction to modern techniques such as computational modelling, and glimpses of outstanding issues.

  15. Nuclear chemistry and geochemistry research. Carnegie Institute of Technology and Carnegie--Mellon University. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Kohman, T.P.

    1976-05-28

    A summary is presented of the activities and results of research in nuclear chemistry, nuclear geochemistry, nuclear cosmochemistry, and other minor areas from 1950 to 1976. A complete listing is given of publications, doctoral dissertations, and reports resulting from the research. A chronological list provides an overview of the activities at any particular time. (JSR)

  16. Organic chemistry in space

    Science.gov (United States)

    Johnson, R. D.

    1977-01-01

    Organic cosmochemistry, organic materials in space exploration, and biochemistry of man in space are briefly surveyed. A model of Jupiter's atmosphere is considered, and the search for organic molecules in the solar system and in interstellar space is discussed. Materials and analytical techniques relevant to space exploration are indicated, and the blood and urine analyses performed on Skylab are described.

  17. Experimental and Analytical Studies of Solar System Chemistry

    Science.gov (United States)

    Burnett, Donald S.

    2003-01-01

    The cosmochemistry research funded by this grant resulted in the publications given in the attached Publication List. The research focused in three areas: (1) Experimental studies of trace element partitioning. (2) Studies of the minor element chemistry and O isotopic compositions of MgAlO4 spinels from Ca-Al-Rich Inclusions in carbonaceous chondrite meteorites, and (3) The abundances and chemical fractionations of Th and U in chondritic meteorites.

  18. Isotopic studies of planetary and nuclear materials: A scientific tribute to Ian Douglass Hutcheon (1947-2015)

    Science.gov (United States)

    Huss, Gary R.

    2017-03-01

    This issue of Geochimica et Cosmochimica Acta is a scientific tribute to Dr. Ian D. Hutcheon (Fig. 1), who passed away on March 26th, 2015. Ian was a pioneer in the fields of isotope cosmochemistry and nuclear forensics, a friend and colleague to many of us, and an effective and dedicated mentor to young scientists. His scientific interests were wide-ranging and are reflected in the papers in this issue. Many of the authors worked closely with him over the years.

  19. Chemistry-nuclear chemistry division. Progress report, October 1979-September 1980

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R.R. (comp.)

    1981-05-01

    This report presents the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, element migration and fixation, inorganic chemistry, isotope separation and analysis, atomic and molecular collisions, molecular spectroscopy, muonic x rays, nuclear cosmochemistry, nuclear structure and reactions, radiochemical separations, theoretical chemistry, and unclassified weapons research.

  20. Modern Meteor Science An Interdisciplinary View

    CERN Document Server

    Hawkes, Robert; Brown, Peter

    2005-01-01

    This volume represents a blend of leading edge research and authoritative reviews in meteor science. It provides a comprehensive view of meteoroid research including the dynamics, sources and distribution of these bodies, and their chemistry and physical processes in the interplanetary medium and the Earth’s atmosphere. Techniques for investigation of meteor phenomena in the book include conventional and large aperture radar systems, spacecraft detection, optical systems, spectral measurements, and laboratory based interplanetary dust particle studies. The book will be of interest to researchers and students in astronomy, astrophysics, cosmochemistry, space engineering and space science. Cover photograph was taken by Masayuki Toda.

  1. Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R.R. (comp.)

    1982-05-01

    This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research.

  2. Experiments in Planetary and Related Sciences and the Space Station

    Science.gov (United States)

    Greeley, Ronald (Editor); Williams, Richard J. (Editor)

    1987-01-01

    Numerous workshops were held to provide a forum for discussing the full range of possible experiments, their science rationale, and the requirements on the Space Station, should such experiments eventually be flown. During the workshops, subgroups met to discuss areas of common interest. Summaries of each group and abstracts of contributed papers as they developed from a workshop on September 15 to 16, 1986, are included. Topics addressed include: planetary impact experimentation; physics of windblown particles; particle formation and interaction; experimental cosmochemistry in the space station; and an overview of the program to place advanced automation and robotics on the space station.

  3. Oral Histories in Meteoritics and Planetary Science—XXI: Donald Burnett

    Science.gov (United States)

    Sears, Derek W. G.

    2013-09-01

    In this interview, Donald Burnett (Fig. 1) describes how he applied to the University of Chicago, with considerable support from his father, where he took classes from Harold Urey and was inspired by Ed Anders to pursue a career in nuclear chemistry and, later, cosmochemistry. As a graduate student at the University of California at Berkeley, Don learned to use charged-particle tracks as a detector for radioactive nuclei, a technique that he applied to a wide variety of problems over the next 20 years, including the neutron profile probe that was deployed on the Moon. After a one-year postdoc with William Fowler at the California Institute of Technology, he became involved with Jerry Wasserburg, who ultimately obtained a faculty position for him in the Geology Division. Since then, Don has worked on a number of fundamental problems in cosmochemistry, chronology of the solar system, the initial Pu/U abundance, fractionation of U and Pu in igneous processes, and elemental abundances. This last interest led him to advocate, propose, and lead the Genesis space mission to collect and return samples of the solar wind. The crash of the return capsule caused alarm, but some aspects of the mission were unaffected and others have been successfully handled, so that several major new results have been published: the lack of an SEP component in lunar samples, the Ne and Ar composition of the solar wind, and, most importantly, the oxygen and nitrogen isotopic composition of the Sun. Don received the Leonard Medal in 2012.

  4. Planetary Science Research Discoveries (PSRD) www.psrd.hawaii.edu

    Science.gov (United States)

    Martel, L.; Taylor, J.

    2010-12-01

    NASA's Year of the Solar System is celebrating not only Solar System mission milestones but also the collective data reduction and analysis that happens here on Earth. The Cosmochemistry Program of NASA's Science Mission Directorate takes a direct approach to enhance student learning and engage the public in the latest research on meteorites, asteroids, planets, moons, and other materials in our Solar System with the website known as PSRD. The Planetary Science Research Discoveries (PSRD) website at www.psrd.hawaii.edu explores the science questions that researchers are actively pursuing about our Solar System and explains how the answers are discovered and what they mean. The site helps to convey the scientific basis for sample study to the broader scientific community and the excitement of new results in cosmochemistry to the general public. We share with our broad audience the fascinating discoveries made by cosmochemists, increasing public awareness of the value of sample-focused research in particular and of fundamental scientific research and space exploration in general. The scope of the website covers the full range of cosmochemical research and highlights the investigations of extraterrestrial materials that are used to better understand the origin of the Solar System and the processes by which planets, moons, and small bodies evolve. We relate the research to broader planetary science themes and mission results. Articles are categorized into: asteroids, comets, Earth, instruments of cosmochemistry, Jupiter system, Mars, Mars life issues, Mercury, meteorites, Moon, origins, and space weathering. PSRD articles are based on peer-reviewed, journal publications. Some PSRD articles are based on more than one published paper in order to present multiple views and outcomes of research on a topic of interest. To date, 150 PSRD articles have been based on 184 journal articles (and counting) written by some of the most active cosmochemists and planetary scientists

  5. Chelyabinsk airburst, damage assessment, meteorite recovery, and characterization.

    Science.gov (United States)

    Popova, Olga P; Jenniskens, Peter; Emel'yanenko, Vacheslav; Kartashova, Anna; Biryukov, Eugeny; Khaibrakhmanov, Sergey; Shuvalov, Valery; Rybnov, Yurij; Dudorov, Alexandr; Grokhovsky, Victor I; Badyukov, Dmitry D; Yin, Qing-Zhu; Gural, Peter S; Albers, Jim; Granvik, Mikael; Evers, Läslo G; Kuiper, Jacob; Kharlamov, Vladimir; Solovyov, Andrey; Rusakov, Yuri S; Korotkiy, Stanislav; Serdyuk, Ilya; Korochantsev, Alexander V; Larionov, Michail Yu; Glazachev, Dmitry; Mayer, Alexander E; Gisler, Galen; Gladkovsky, Sergei V; Wimpenny, Josh; Sanborn, Matthew E; Yamakawa, Akane; Verosub, Kenneth L; Rowland, Douglas J; Roeske, Sarah; Botto, Nicholas W; Friedrich, Jon M; Zolensky, Michael E; Le, Loan; Ross, Daniel; Ziegler, Karen; Nakamura, Tomoki; Ahn, Insu; Lee, Jong Ik; Zhou, Qin; Li, Xian-Hua; Li, Qiu-Li; Liu, Yu; Tang, Guo-Qiang; Hiroi, Takahiro; Sears, Derek; Weinstein, Ilya A; Vokhmintsev, Alexander S; Ishchenko, Alexei V; Schmitt-Kopplin, Phillipe; Hertkorn, Norbert; Nagao, Keisuke; Haba, Makiko K; Komatsu, Mutsumi; Mikouchi, Takashi

    2013-11-29

    The asteroid impact near the Russian city of Chelyabinsk on 15 February 2013 was the largest airburst on Earth since the 1908 Tunguska event, causing a natural disaster in an area with a population exceeding one million. Because it occurred in an era with modern consumer electronics, field sensors, and laboratory techniques, unprecedented measurements were made of the impact event and the meteoroid that caused it. Here, we document the account of what happened, as understood now, using comprehensive data obtained from astronomy, planetary science, geophysics, meteorology, meteoritics, and cosmochemistry and from social science surveys. A good understanding of the Chelyabinsk incident provides an opportunity to calibrate the event, with implications for the study of near-Earth objects and developing hazard mitigation strategies for planetary protection.

  6. Irradiation history of meteoritic inclusions

    DEFF Research Database (Denmark)

    Wielandt, Daniel Kim Peel

    -sun. To the scientists that study them, they represent a rich archive of the dynamic processes that lead to the formation of our sol r system and eventually the planetary system that we observe today. Although meteorites and their components have been studied for several hundred years, the recent decades of mass......Understanding the formation and earliest evolution of our solar system is a longstanding goal shared by cosmochemistry, astronomy and astrophysics. Meteorites play a key role in this pursuit, providing a ground truth against which all theories must be weighed. Chondritic meteorites are in essence...... extraterrestrial sediments that contain Calcium-Aluminium-rich Inclusions (CAIs) and chondrules that formed as individual objects during the earliest stages of solar system evolution. They later accreted together to form large bodies, after spending up to several million years in individual orbit around the proto...

  7. Volatiles in protoplanetary disks

    CERN Document Server

    Pontoppidan, Klaus M; Bergin, Edwin A; Brittain, Sean; Marty, Bernard; Mousis, Olvier; Oberg, Karin L

    2014-01-01

    Volatiles are compounds with low sublimation temperatures, and they make up most of the condensible mass in typical planet-forming environments. They consist of relatively small, often hydrogenated, molecules based on the abundant elements carbon, nitrogen and oxygen. Volatiles are central to the process of planet formation, forming the backbone of a rich chemistry that sets the initial conditions for the formation of planetary atmospheres, and act as a solid mass reservoir catalyzing the formation of planets and planetesimals. This growth has been driven by rapid advances in observations and models of protoplanetary disks, and by a deepening understanding of the cosmochemistry of the solar system. Indeed, it is only in the past few years that representative samples of molecules have been discovered in great abundance throughout protoplanetary disks - enough to begin building a complete budget for the most abundant elements after hydrogen and helium. The spatial distributions of key volatiles are being mapped...

  8. The Urey instrument: an advanced in situ organic and oxidant detector for Mars exploration.

    Science.gov (United States)

    Aubrey, Andrew D; Chalmers, John H; Bada, Jeffrey L; Grunthaner, Frank J; Amashukeli, Xenia; Willis, Peter; Skelley, Alison M; Mathies, Richard A; Quinn, Richard C; Zent, Aaron P; Ehrenfreund, Pascale; Amundson, Ron; Glavin, Daniel P; Botta, Oliver; Barron, Laurence; Blaney, Diana L; Clark, Benton C; Coleman, Max; Hofmann, Beda A; Josset, Jean-Luc; Rettberg, Petra; Ride, Sally; Robert, François; Sephton, Mark A; Yen, Albert

    2008-06-01

    The Urey organic and oxidant detector consists of a suite of instruments designed to search for several classes of organic molecules in the martian regolith and ascertain whether these compounds were produced by biotic or abiotic processes using chirality measurements. These experiments will also determine the chemical stability of organic molecules within the host regolith based on the presence and chemical reactivity of surface and atmospheric oxidants. Urey has been selected for the Pasteur payload on the European Space Agency's (ESA's) upcoming 2013 ExoMars rover mission. The diverse and effective capabilities of Urey make it an integral part of the payload and will help to achieve a large portion of the mission's primary scientific objective: "to search for signs of past and present life on Mars." This instrument is named in honor of Harold Urey for his seminal contributions to the fields of cosmochemistry and the origin of life.

  9. Quantum chemical study of relative reactivities of a series of amines and nitriles - Relevance to prebiotic chemistry

    Science.gov (United States)

    Loew, G. H.; Berkowitz, D.; Chang, S.

    1975-01-01

    Using the Iterative Extended Huckel Theory (IEHT) calculations of the electron distribution and orbital energies of a series of thirteen amines, nitriles and amino-nitriles relevant to prebiotic and cosmo-chemistry have been carried out. Ground state properties such as the energy and nature of the highest occupied (HOMO) and lowest empty (LEMO) molecular orbitals, net atomic charges and number of nonbonding electrons have been identified as criteria for correlating the relative nucleophilicity of amine and nitrile nitrogens and the electrophilicity of nitrile and other unsaturated carbon atoms. The results of such correlations can be partially verified by known chemical behavior of these compounds and are used to predict and understand their role in prebiotic organic synthesis.

  10. Topics in nuclear and radiochemistry for college curricula and high school science programs

    Energy Technology Data Exchange (ETDEWEB)

    1990-01-01

    The concern with the current status and trends of nuclear chemistry and radiochemistry education in academic institutions was addressed in a recent workshop. The 1988 workshop considered the important contributions that scientist with nuclear and radiochemistry backgrounds have made and are continuing to make to other sciences and to various applied fields. Among the areas discussed were environmental studies, life sciences, materials science, separation technology, hot atom chemistry, cosmochemistry, and the rapidly growing field of nuclear medicine. It is intent of the organizer and participants of this symposium entitled Topics in Nuclear and Radiochemistry for College Curricula and High School Science Program'' to provide lecture material on topics related to nuclear and radiochemistry to educators. It is our hope that teachers, who may or may not be familiar with the field, will find this collections of articles useful and incorporate some of them into their lectures.

  11. Quantum chemical study of relative reactivities of a series of amines and nitriles - Relevance to prebiotic chemistry

    Science.gov (United States)

    Loew, G. H.; Berkowitz, D.; Chang, S.

    1975-01-01

    Using the Iterative Extended Huckel Theory (IEHT) calculations of the electron distribution and orbital energies of a series of thirteen amines, nitriles and amino-nitriles relevant to prebiotic and cosmo-chemistry have been carried out. Ground state properties such as the energy and nature of the highest occupied (HOMO) and lowest empty (LEMO) molecular orbitals, net atomic charges and number of nonbonding electrons have been identified as criteria for correlating the relative nucleophilicity of amine and nitrile nitrogens and the electrophilicity of nitrile and other unsaturated carbon atoms. The results of such correlations can be partially verified by known chemical behavior of these compounds and are used to predict and understand their role in prebiotic organic synthesis.

  12. Chemical evolution and the origin of life

    Science.gov (United States)

    Oro, J.

    1983-01-01

    A review is presented of recent advances made in the understanding of the formation of carbon compounds in the universe and the occurrence of processes of chemical evolution. Topics discussed include the principle of evolutionary continuity, evolution as a fundamental principle of the physical universe, the nuclear synthesis of biogenic elements, organic cosmochemistry and interstellar molecules, the solar nebula and the solar system in chemical evolution, the giant planets and Titan in chemical evolution, and comets and their interaction with the earth. Also examined are carbonaceous chondrites, environment of the primitive earth, energy sources available on the primitive earth, the synthesis of biochemical monomers and oligomers, the abiotic transcription of nucleotides, unified prebiotic and enzymatic mechanisms, phospholipids and membranes, and protobiological evolution.

  13. Nuclear astrophysics: the unfinished quest for the origin of the elements

    CERN Document Server

    Jose, Jordi

    2011-01-01

    Half a century has passed since the foundation of nuclear astrophysics. Since then, this discipline has reached its maturity. Today, nuclear astrophysics constitutes a multidisciplinary crucible of knowledge that combines the achievements in theoretical astrophysics, observational astronomy, cosmochemistry and nuclear physics. New tools and developments have revolutionized our understanding of the origin of the elements: supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists have measured reactions near stellar energies, through the combined eff...

  14. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  15. Progress in the Early Solar System Chronology: A Sketch of an Ever-Changing Landscape

    Science.gov (United States)

    Amelin, Yuri; Yin, Q.-Z.; Krot, A. N.; Bouvier, A.; Wadhwa, M.; Kleine, T.; Nyquist, L. E.

    2011-01-01

    The years since the Workshop on the Chronology of Meteorites and the Early Solar System, are marked with ongoing progress in cosmochronology. Rapid improvements in techniques, discovery of new meteorites unlike any previously known, and findings that what was deemed well established constants are actually variables, will be reflected in an updated review of the solar system chronology we are currently preparing. Along with updating the database of meteorite ages, it will involve development of a set of criteria for evaluation of accuracy and consistency of isotopic dates across the entire range of meteorite classes and isotope chronometer systems. Here we present some ideas on what we think is important in meteorite chronology, and invite the cosmochemistry community to discuss them.

  16. Investigation of Isotope Anomalies in Meteorites and their Components

    DEFF Research Database (Denmark)

    Holst, Jesper Christian

    and earliest evolution of the solar system through the chemical and isotopic study of meteorites. One area of cosmochemistry that has benefited from high-precision mass spectrometry is that of early solar system chronology. Several radioactive isotopes with short and long half-lives are known to have been...... thermal events caused by the actively accreting protosun, an initial well-mixed disk could evolve to isotopic heterogeneity over time. Such extensive thermal processing is likely recorded in a range of elements as any element present in anomalous presolar carrier grains would be isotopically distinct from....... Moreover, high-precision tungsten and zirconium isotope results for bulk meteorites and inclusions help constrain the nature and degree of processing experienced by dust and gas present in the protoplanetary disk. Our results show that short-lived radionuclei 182Hf and 26Al had different stellar sources...

  17. PME Augmentation to Isotopic Investigations Relevant to Origins of Solar Systems

    Science.gov (United States)

    Yin, Qing-zhu

    We propose to acquire a state-of-the-art, next generation, ultra high precision and high sensitivity thermal ionization mass spectrometer (TIMS) at the University of California, Davis (UC Davis) for isotope cosmochemistry research that is highly relevant to NASA's Origins of Solar Systems program. UC Davis will contribute 10% of the total budget (87,791) from the PI's start-up fund to share the cost of the proposed equipment. We request partial funding (790,118) from the Planetary Major Equipment program to cover the remaining cost of the instrument, as an augmentation to the existing science research award from the Origins of Solar Systems (OSS) program (NNX09AC93G) to the PI (Qing-Zhu Yin). The proposed instrument acquisition is vital to accomplish the research objectives outlined in the original OSS award (NNX09AC93G) and Cosmochemistry award (NNX08AG57G) to the PI. To ensure investigator access to and further development of new techniques that expand our research goals, the PI needs a TIMS as an Investigator Instrument (using NASA terminology). The University of California, Davis is fully committed to supporting isotope geochemistry and cosmochemistry research, as manifested through the promotion of the PI as a tenured faculty member effective July 1, 2008, providing the matching funds for cost sharing of the proposed instrument purchase, and a class-100 clean lab space (640 square feet) for sample handling in the new Earth and Physical Sciences building. The proposed acquisition is highly relevant to the scope of NASA's Origins of Solar Systems program: i.e., to conduct scientific investigations related to understanding the formation and early evolution of planetary systems in the area of analysis of primitive materials, solar nebular processes, star formation and its relationship to planetary system formations. The acquisition will help to generate new data and contribute to the development of new techniques that closely support NASA's activities for future

  18. Searching for Extraterrestrial Amino Acids in a Contaminated Meteorite: Amino Acid Analyses of the Canakkale L6 Chondrite

    Science.gov (United States)

    Burton, A. S.; Elsila, J. E.; Glavin, D. P.; Dworkin, J. P.; Ornek, C. Y.; Esenoglu, H. H.; Unsalan, O.; Ozturk, B.

    2016-01-01

    Amino acids can serve as important markers of cosmochemistry, as their abundances and isomeric and isotopic compositions have been found to vary predictably with changes in parent body chemistry and alteration processes. Amino acids are also of astrobiological interest because they are essential for life on Earth. Analyses of a range of meteorites, including all groups of carbonaceous chondrites, along with H, R, and LL chondrites, ureilites, and a martian shergottite, have revealed that amino acids of plausible extraterrestrial origin can be formed in and persist after a wide range of parent body conditions. However, amino acid analyses of L6 chondrites to date have not provided evidence for indigenous amino acids. In the present study, we performed amino acid analysis on larger samples of a different L6 chondite, Canakkale, to determine whether or not trace levels of indigenous amino acids could be found. The Canakkale meteor was an observed fall in late July, 1964, near Canakkale, Turkey. The meteorite samples (1.36 and 1.09 g) analyzed in this study were allocated by C. Y. Ornek, along with a soil sample (1.5 g) collected near the Canakkale recovery site.

  19. Insight into Primordial Solar System Oxygen Reservoirs from Returned Cometary Samples

    Science.gov (United States)

    Brownlee, D. E.; Messenger, S.

    2004-01-01

    The recent successful rendezvous of the Stardust spacecraft with comet Wild-2 will be followed by its return of cometary dust to Earth in January 2006. Results from two separate dust impact detectors suggest that the spacecraft collected approximately the nominal fluence of at least 1,000 particles larger than 15 micrometers in size. While constituting only about one microgram total, these samples will be sufficient to answer many outstanding questions about the nature of cometary materials. More than two decades of laboratory studies of stratospherically collected interplanetary dust particles (IDPs) of similar size have established the necessary microparticle handling and analytical techniques necessary to study them. It is likely that some IDPs are in fact derived from comets, although complex orbital histories of individual particles have made these assignments difficult to prove. Analysis of bona fide cometary samples will be essential for answering some fundamental outstanding questions in cosmochemistry, such as (1) the proportion of interstellar and processed materials that comprise comets and (2) whether the Solar System had a O-16-rich reservoir. Abundant silicate stardust grains have recently been discovered in anhydrous IDPs, in far greater abundances (200 5,500 ppm) than those in meteorites (25 ppm). Insight into the more subtle O isotopic variations among chondrites and refractory phases will require significantly higher precision isotopic measurements on micrometer-sized samples than are currently available.

  20. Thermochemistry of CaO-MgO-Al2O3-SiO2 (CMAS) and Advanced Thermal and Environmental Barrier Coating Systems

    Science.gov (United States)

    Costa, Gustavo C. C.; Zhu, Dongming

    2016-01-01

    CaO-MgO-Al2O3-SiO2 (CMAS) oxides are constituents in a broad number of materials and minerals which have recently inferred to discussions in materials science, planetary science, geochemistry and cosmochemistry communities. In materials science, there is increasing interest in the degradation studies of thermal (TBC) and environmental (EBC) barrier coatings of gas turbines by molten CMAS. These coatings have been explored to be applied on silicon-based ceramics and composites which are lighter and more temperature capable hot-section materials of gas turbines than the current Ni-based superalloys. The degradation of the coatings occurs when CMAS minerals carried by the intake air into gas turbines, e.g. in aircraft engines, reacts at high temperatures (1000C) with the coating materials. This causes premature failure of the static and rotating components of the turbine engines. We discuss some preliminary results of the reactions between CMAS and Rare-Earth (RE Y, Yb and Gd) oxide stabilized ZrO2 systems, and stability of the resulting oxides and silicates.

  1. Report on the Sixth International Symposium on Isotopomers

    Energy Technology Data Exchange (ETDEWEB)

    Bao, H. [Louisiana State Univ., Baton Rouge, LA (United States); Farquhar, J. [Univ. of Maryland, College Park, MD (United States); Rumble, D. [Carnegie Inst. of Washington, Argonne, IL (United States). Geophysical Lab.

    2016-05-11

    The ISI 2012 met in Washington, DC, 18-22 June 2012, bringing together researchers and their students spanning an unusually wide range of disciplines including quantum and physical chemistry, cosmochemistry, atmospheric chemistry, chemical oceanography, biogeochemistry, organic and inorganic geochemistry. The diversity of subject matter was matched geographically with 92 attendees hailing from Canada, China, Finland, France, Germany, India, Israel, Japan, the Netherlands, Russia, Switzerland, Taiwan, the United Kingdom, and the USA. Although diverse, the group was united in its commitment to use the light stable isotopes of H, C, N, O, and S, with their equilibrium, kinetic, and intramolecular fractionations, to understand the material cycles and their dynamics between atmosphere, biosphere, hydrosphere, and lithosphere that make life possible on Earth. A distinct benefit of a small meeting like ISI 2012 is the opportunity for everyone to talk to each other. The historic rooms of the Carnegie Institution of Washington offered a cozy and warm atmosphere for participants in ISI 2012 to talk science and life in a casual, relaxed, and in-depth fashion. Graduate students and postdoctoral researchers were particularly appreciative of being able to spend five days together with old and new colleagues in comfortable quarters. Many commented that they had gained a lot more in building their life-long working relationships with colleagues at this meeting than at larger meetings.

  2. Enantiomeric excesses of chiral amines in ammonia-rich carbonaceous meteorites

    Science.gov (United States)

    Pizzarello, Sandra; Yarnes, Christopher T.

    2016-06-01

    Chiral homogeneity is essential to the structure and function of terrestrial biopolymers but the origin of this "homochirality" is poorly understood and remains one of the many unknowns surrounding the origins of life. Several amino acids extracted from Carbonaceous Chondrite meteorites display L-enantiomeric excesses (ee) and their findings have encouraged suggestions that an input of non-racemic meteoritic compounds to early Earth might have led to terrestrial homochirality. Motivated by occasional indications of possible ee in other classes of soluble meteoritic compounds, we have undertaken a systematic study of the chiral distribution of amines in Renazzo-type (CR) meteorites, where they are the second most abundant organic molecular species and ammonia is by far the most abundant single molecule. We report here the first time finding of L-ee for two chiral amines in several pristine CR meteorites from Antarctica and outline a proposal by which the compounds possibly formed from the same ketone precursors as some of the chiral amino acids. This would occur during a warm hydrous stage of the asteroidal parent body, via a reductive amination process in the presence of a large abundance of ammonia, where the precursors' adsorption upon mineral phases possessing asymmetry offered the opportunity for chiral induction. Because the precursor ketones are achiral, the proposal underscores the likelihood of diverse asymmetric influences and processes in cosmochemistry.

  3. Effect of plate bending on the Urey ratio and the thermal evolution of the mantle

    Science.gov (United States)

    Davies, Geoffrey F.

    2009-10-01

    The bending of tectonic plates as they subduct causes resistance to plate motions and mantle convection. It has been proposed that this effect could keep plate velocities relatively constant with time, and it would imply relatively high mantle temperatures through much of Earth history and relatively rapid cooling at present. It also implies a low Urey ratio, compatible with that inferred from cosmochemistry. Here it is confirmed that bending resistance only plays a significant role if plate thickness is determined mainly by dehydration stiffening accompanying melting, rather than by conductive cooling. Even then the bending resistance is quite sensitive to the radius of curvature of the subducting plate. Observed radii are generally larger than the 200 km assumed in some studies, ranging up to 600 km or more. Furthermore radii of curvature tend to adjust so as to prevent bending resistance from becoming large. When these factors are accounted for, calculations show that bending resistance is unlikely to have been a large factor through Earth history, and the thermal evolution of the mantle is unlikely to have been affected very much. The resolution of the Urey ratio problem should then be sought elsewhere.

  4. Rubidium isotopic composition of the Earth, meteorites, and the Moon: Evidence for the origin of volatile loss during planetary accretion

    Science.gov (United States)

    Pringle, Emily A.; Moynier, Frédéric

    2017-09-01

    Understanding the origin of volatile element variations in the inner Solar System has long been a goal of cosmochemistry, but many early studies searching for the fingerprint of volatile loss using stable isotope systems failed to find any resolvable variations. An improved method for the chemical purification of Rb for high-precision isotope ratio measurements by multi-collector inductively-coupled-plasma mass-spectrometry. This method has been used to measure the Rb isotopic composition for a suite of planetary materials, including carbonaceous, ordinary, and enstatite chondrites, as well as achondrites (eucrite, angrite), terrestrial igneous rocks (basalt, andesite, granite), and Apollo lunar samples (mare basalts, alkali suite). Volatile depleted bodies (e.g. HED parent body, thermally metamorphosed meteorites) are enriched in the heavy isotope of Rb by up to several per mil compared to chondrites, suggesting volatile loss by evaporation at the surface of planetesimals. In addition, the Moon is isotopically distinct from the Moon in Rb. The variations in Rb isotope compositions in the volatile-poor samples are attributed to volatile loss from planetesimals during accretion. This suggests that either the Rb (and other volatile elements) were lost during or following the giant impact or by evaporation earlier during the accretion history of Theia.

  5. Nuclear microprobe and nuclear reaction spectrometry at a few square micrometer level: myth or reality

    Energy Technology Data Exchange (ETDEWEB)

    Trocellier, P. E-mail: ptrocel@nimitz.saclay.cea.fr; Berger, P.; Berthier, B.; Berthoumieux, E.; Gallien, J.P.; Metrich, N.; Moreau, C.; Mosbah, M.; Varela, M.E

    1999-09-02

    Proton induced X-ray emission and Rutherford backscattering spectrometry are the most often used IBA methods in conjunction with a nuclear microprobe. Their main advantages derive both from the corresponding cross sections having relatively high values and their multielemental response. {mu}PIXE allows one to reach the spatial distribution of elements with Z>12 and {mu}RBS permits the study of multilayered solids with a good selectivity for thin heavy element layers deposited on light substrates. Nuclear reactions on the other hand generally exhibit low cross section values but are well adapted for light element isotope measurements in any substrate. This paper intends to provide an overview of nuclear reaction spectrometry analytical capabilities using {sup 1}H, {sup 2}H, {sup 3}He or {sup 4}He microbeams. Practical performances such as selectivity, sensitivity, total analysable depth and depth resolution are discussed. Finally, application examples are presented in the following areas: metallurgy and material sciences, earth sciences and cosmochemistry, biochemistry and archaeometry.

  6. Organic geochemistry - A retrospective of its first 70 years

    Science.gov (United States)

    Kvenvolden, K.A.

    2006-01-01

    Organic geochemistry had its origin in the early part of the 20th century when organic chemists and geologists realized that detailed information on the organic materials in sediments and rocks was scientifically interesting and of practical importance. The generally acknowledged "father" of organic geochemistry is Alfred E. Treibs (1899-1983), who discovered and described, in 1936, porphyrin pigments in shale, coal, and crude oil, and traced the source of these molecules to their biological precursors. Thus, the year 1936 marks the beginning of organic geochemistry. However, formal organization of organic geochemistry dates from 1959 when the Organic Geochemistry Division (OGD) of The Geochemical Society was founded in the United States, followed 22 years later (1981) by the establishment of the European Association of Organic Geochemists (EAOG). Organic geochemistry (1) has its own journal, Organic Geochemistry (beginning in 1979) which, since 1988, is the official journal of the EAOG, (2) convenes two major conferences [International Meeting on Organic Geochemistry (IMOG), since 1962, and Gordon Research Conferences on Organic Geochemistry (GRC), since 1968] in alternate years, and (3) is the subject matter of several textbooks. Organic geochemistry is now a widely recognized geoscience in which organic chemistry has contributed significantly not only to geology (i.e., petroleum geochemistry, molecular stratigraphy) and biology (i.e., biogeochemistry), but also to other disciplines, such as chemical oceanography, environmental science, hydrology, biochemical ecology, archaeology, and cosmochemistry.

  7. Nuclear astrophysics: the unfinished quest for the origin of the elements

    Energy Technology Data Exchange (ETDEWEB)

    Jose, Jordi [Departament de Fisica i Enginyeria Nuclear, EUETIB, Universitat Politecnica de Catalunya, E-08036 Barcelona (Spain); Iliadis, Christian, E-mail: jordi.jose@upc.edu, E-mail: iliadis@unc.edu [Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599 (United States)

    2011-09-15

    Half a century has passed since the foundation of nuclear astrophysics. Since then, this discipline has reached its maturity. Today, nuclear astrophysics constitutes a multidisciplinary crucible of knowledge that combines the achievements in theoretical astrophysics, observational astronomy, cosmochemistry and nuclear physics. New tools and developments have revolutionized our understanding of the origin of the elements: supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists have measured reactions near stellar energies, through the combined efforts using stable and radioactive-ion beam facilities. This review provides comprehensive insight into the nuclear history of the Universe and related topics: starting from the Big Bang, when the ashes from the primordial explosion were transformed to hydrogen, helium and a few trace elements, to the rich variety of nucleosynthesis mechanisms and sites in the Universe. Particular attention is paid to the hydrostatic processes governing the evolution of low-mass stars, red giants and asymptotic giant-branch stars, as well as to the explosive nucleosynthesis occurring in core-collapse and thermonuclear supernovae, {gamma}-ray bursts, classical novae, x-ray bursts, superbursts and stellar mergers.

  8. Physics in a mad world

    CERN Document Server

    2015-01-01

    This book tells captivating stories of misadventures of two renowned theoretical physicists in the Soviet Union. The first part is devoted to Friedrich (Fritz) Houtermans, an outstanding Dutch–Austrian–German physicist who was the first to suggest that the source of stars' energy is thermonuclear fusion, and also made a number of other important contributions to cosmochemistry and geochemistry. In 1935, Houtermans, a German communist, in an attempt to save his life from Hilter's Gestapo, fled to the Soviet Union. He took up an appointment at the Kharkov Physico-Technical Institute, working there for two years with the Russian physicist Valentin P Fomin. In the Great Purge of 1937, Houtermans was arrested in December by the NKVD (Soviet Secret Police, KGB's predecessor). He was tortured, and confessed to being a Trotskyist plotter and German spy, out of fear of threats against his wife Charlotte. However, Charlotte had already escaped from the Soviet Union to Denmark, after which she went to England and fi...

  9. Extraterrestrial materials examined by mean of nuclear microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Khodja, H., E-mail: hicham.khodja@cea.fr [CEA/IRAMIS/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France); CNRS/UMR 3299/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France); Smith, T. [CEA/IRAMIS/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France); CNRS/UMR 3299/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France); Engrand, C. [CSNSM, Bat 104, F-91405, Orsay Campus (France); Herzog, G. [Department of Chemistry and Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854-8087 (United States); Raepsaet, C. [CEA/IRAMIS/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France); CNRS/UMR 3299/SIS2M/LEEL, F-91191 Gif-sur-Yvette (France)

    2013-07-01

    Comet fragments, micrometeorites, and Interplanetary Dust Particles (IDPs) are small objects (<1 mm) of high scientific interest in cosmochemistry. More particularly, the determination of light element concentrations, such as C and N, in cometary samples is of interest since it gives information on the regions where such materials formed. Analyses of such objects should be performed so as to extract as much information as possible while preserving sample integrity. For this purpose, we need instruments and methods that provide both microanalysis and detailed imaging. In these respects, the nuclear microprobe offers many potential advantages: (i) the spatial resolution, ∼1 μm is well-matched to the typical object dimensions, (ii) with some reservations, it is non-destructive when carefully conducted, (iii) it is quantitative, and especially sensitive for light elements. At the Saclay nuclear microprobe, we have been performing analyses of extraterrestrial objects for many years. We review some of these studies, emphasizing the specific requirements for successful analyses. We also discuss the potential pitfalls that may be encountered.

  10. A new combined nanoSIMS and continuous-flow IRMS approach to measure hydrogen isotopes from water in hydrated rhyolitic glass

    Science.gov (United States)

    Gatti, E.; Kitchen, N.; Newman, S.; Guan, Y.; Westgate, J.; Pearce, N. J. G.; Nikolic, D.; Eiler, J. M.

    2016-12-01

    The hydrogen-isotope value of water of hydration (or secondary water) preserved in rhyolitic glasses may provide significant insights regarding the climate at the time of their deposition and the impact of super-eruptions upon the environment. However, the ability of the glass to retain the environmental D/H isotopic signal after hydration needs to be tested, since modifications to the D/H systematics may result from the continuous exchange of D/H with the atmosphere or condensed water after initial glass hydration. Ideal geological archives to test whether the glass retains its original hydrogen signal are sediments in natural waters and ice cores, which preserve tephra in constrained horizons that can be independently isotopically characterised. However, tephra in marine and fresh water sediments and ice cores are often present in concentrations of the order of 1000 grains/cm3 (3 wt%) or 15 mg of dry ( 0.5 wt%) obsidian chips. The method can be improved by reducing the blank to <1 nmol/min and reducing capillary empty space. The bulk results obtained with the continuous-flow IRMS method will be compared to sub-micron mapping of single-grains using a high-resolution ion microprobe, the CAMECA NanoSIMS 50L, in the Microanalysis Center for Geochemistry and Cosmochemistry at California Institute of Technology, in order to define the reliability of the bulk method and assess natural variability within and among grains.

  11. Fifth Anniversary of GEOCHIM 2003/UNESCO “Postgraduate certificated training course in geochemical exploration methods and their environmental applications”

    Institute of Scientific and Technical Information of China (English)

    Dr,JanPasava

    2004-01-01

    It has been a tradition to organize very successful UNESCO Postgraduate Courses on Geochemical Prospecting Methods in the former Czechoslovakia from mid 70's. The first certificated course--GEOCHIM PRAHA UNESCO 1975 was launched on September 5, 1975 and lasted till October 25, 1975. Since that time this course has been organized biannually by the Czech Geological Survey in Prague together with the Dionyz Stur Geological Survey in Bratislava and sponsored by the Division of Earth Sciences (UNESCO/Paris) and the International Association of Geochemistry and Cosmochemistry (IAGS). The course was specialized on both theoretical and practical training in classical geochemical prospecting methods. A team of internationally experienced geoscientists as Drs.J.Pokorny, F.Mma, J.Manour, V.Lomozova Z. Sulcek,I. Rubeska, A.Spackova, V.Sixta, J.Juna,J.Veselu, J.Dornic and others, co-ordinated by Dr. Zdenek Pacal from the Czech Geological Survey in Prague has soon earned high international reputation and the GEOCHIM CSSR UNESCO Postgraduate Course developed into one of the most successful Postgraduate Training Programmes of UNESCO.

  12. Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals.

    Science.gov (United States)

    Pearce, Ben K D; Pudritz, Ralph E

    2016-11-01

    The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We investigated the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identified the two most important reactions for each nucleobase and found that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built. The primary result of this study is that cytosine is unlikely to persist within meteorite parent bodies due to aqueous deamination. Thymine has a thermodynamically favorable reaction pathway from uracil, formaldehyde, and formic acid but likely did not persist within planetesimals containing H2O2 due to an oxidation reaction with this molecule. Finally, while Fischer-Tropsch (FT) synthesis is found to be the dominant source of nucleobases within our model planetesimal, non-catalytic (NC) synthesis may still be significant under certain chemical conditions (e.g., within CR2 parent bodies). We discuss several major consequences of our results for the origin of the RNA world. Key Words: Astrobiology-Cosmochemistry-Meteorites-RNA world-Abiotic organic synthesis. Astrobiology 16, 853-872.

  13. Physical and Chemical Study of Minerals and Rocks Containing Low-Z Compounds of Interest to Astrobiology and Origin of Life

    Science.gov (United States)

    1999-01-01

    Understanding the origins of Life requires a good understanding of the physics and chemistry of biogenic low-z elements H, C, N, O, P, S in terrestrial environments, on Mars, on extraterrestrial bodies such as meteorite parent bodies and comets, and in interstellar space. In this Proposal five Tasks form a coherent program aimed at elucidating various aspects of low-z element geo- and cosmochemistry with special reference to the origin of Life on Earth and to the search for life on Mars, extant or extinct. (i) Formation of organic molecules, in particular oxygenated H-C-0 molecules or precursors thereof of the composition H(x)C(y)O(z)(n-), inside the hard matrix of structurally dense magmatic minerals; (ii) Formation of organic molecules inside the soft matrix of amorphous and crystalline water ice; (iii) Preservation of organic molecules in cherts and other siliceous rocks formed in hot spring or submarine hydrothermal vent environments; (iv) The nature of the elusive Martian soil oxidant; and (v) Prototype development of an XRD instrument, using a new patented XRD camera concept that utilizes a Charge Coupled Device (CCD) as a camera and as a energy-dispersive analyzer.

  14. Noble Gases

    Science.gov (United States)

    Podosek, F. A.

    2003-12-01

    The noble gases are the group of elements - helium, neon, argon, krypton, xenon - in the rightmost column of the periodic table of the elements, those which have "filled" outermost shells of electrons (two for helium, eight for the others). This configuration of electrons results in a neutral atom that has relatively low electron affinity and relatively high ionization energy. In consequence, in most natural circumstances these elements do not form chemical compounds, whence they are called "noble." Similarly, much more so than other elements in most circumstances, they partition strongly into a gas phase (as monatomic gas), so that they are called the "noble gases" (also, "inert gases"). (It should be noted, of course, that there is a sixth noble gas, radon, but all isotopes of radon are radioactive, with maximum half-life a few days, so that radon occurs in nature only because of recent production in the U-Th decay chains. The factors that govern the distribution of radon isotopes are thus quite different from those for the five gases cited. There are interesting stories about radon, but they are very different from those about the first five noble gases, and are thus outside the scope of this chapter.)In the nuclear fires in which the elements are forged, the creation and destruction of a given nuclear species depends on its nuclear properties, not on whether it will have a filled outermost shell when things cool off and nuclei begin to gather electrons. The numerology of nuclear physics is different from that of chemistry, so that in the cosmos at large there is nothing systematically special about the abundances of the noble gases as compared to other elements. We live in a very nonrepresentative part of the cosmos, however. As is discussed elsewhere in this volume, the outstanding generalization about the geo-/cosmochemistry of the terrestrial planets is that at some point thermodynamic conditions dictated phase separation of solids from gases, and that the

  15. Application of the Zr/Hf ratio in the determination of hafnium in geochemical samples by high-resolution inductively coupled plasma mass spectrometry.

    Science.gov (United States)

    Liu, Ya Xuan; Li, Qing Xia; Ma, Na; Sun, Xiao Ling; Bai, Jin Feng; Zhang, Qin

    2014-12-02

    Hafnium content and its change are of significance in geochemistry and cosmochemistry; however, the determination of hafnium has always been problematic in analytical chemistry. In this paper, a new idea is proposed for the determination of hafnium in geochemical samples, including rocks, soils, and stream sediments. Through the comparison of two conventional open-type acid digestion methods (HF-HNO3-HClO4 and HF-HNO3-H2SO4), it was found that although neither of these methods could fully digest the zirconium and hafnium in a sample, the zirconium and hafnium digestion behaviors in one sample were consistent in the 60 experimental geochemical reference materials with different properties, so the experimentally determined Zr/Hf ratio in solution could be used to calculate the hafnium content in a sample. In addition, possible mass spectral interferences during the determination of zirconium and hafnium by high resolution inductively coupled plasma mass spectrometry (HR-ICPMS) were studied, and it was found that the mass spectral interferences of the selected isotopes (90)Zr and (178)Hf could be neglected. The mass spectral behaviors of (90)Zr and (178)Hf were also very consistent during the determination by HR-ICPMS. Since the hafnium content was calculated using the ratio value, all of the errors (including the errors in weighing process, the accidental errors during operation and the instrument fluctuation in the determination) of the Zr/Hf ratio could be effectively reduced or even eliminated. The relative standard deviation of the actual samples was lower than 3.2%, and the detection limit of the method (considering the dilution effect and matrix effect during measurement of the Zr/Hf ratio and zirconium content) was 0.04 μg/g. The proposed method could satisfy the requirement for the determination of hafnium in geochemical samples.

  16. Institute of Geophyics and Planetary Physics. Annual report for FY 1994

    Energy Technology Data Exchange (ETDEWEB)

    Ryerson, F.J. [ed.

    1995-09-29

    The Institute of Geophysics and Planetary Physics (IGPP) is a Multicampus Research Unit of the University of California (UC). IGPP was founded in 1946 at UC Los Angeles with a charter to further research in the earth and planetary sciences and in related fields. The Institute now has branches at UC campuses in Los Angeles, San Diego, Riverside, and Irvine and at Los Alamos and Lawrence Livermore national laboratories. The University-wide IGPP has played an important role in establishing interdisciplinary research in the earth and planetary sciences. For example, IGPP was instrumental in founding the fields of physical oceanography and space physics, which at the time fell between the cracks of established university departments. Because of its multicampus orientation, IGPP has sponsored important interinstitutional consortia in the earth and planetary sciences. Each of the six branches has a somewhat different intellectual emphasis as a result of the interplay between strengths of campus departments and Laboratory programs. The IGPP branch at Lawrence Livermore National Laboratory (LLNL) was approved by the Regents of the University of California in 1982. IGPP-LLNL emphasizes research in seismology, geochemistry, cosmochemistry, high-pressure sciences, and astrophysics. It provides a venue for studying the fundamental aspects of these fields, thereby complementing LLNL programs that pursue applications of these disciplines in national security and energy research. IGPP-LLNL is directed by Charles Alcock and is structured around three research centers. The Center for Geosciences, headed by George Zandt and Frederick Ryerson, focuses on research in geophysics and geochemistry. The Center for High-Pressure Sciences, headed by William Nellis, sponsors research on the properties of planetary materials and on the synthesis and preparation of new materials using high-pressure processing.

  17. DUSTER: collection of meteoric CaO and carbon smoke particles in the upper stratosphere .

    Science.gov (United States)

    Della Corte, V.; Rietmeijer, F. J. M.; Rotundi, A.; Ferrari, M.; Palumbo, P.

    Nanometer- to micrometer-size particles present in the upper stratosphere are a mixture of terrestrial and extra-terrestrial origins. They can be extraterrestrial particles condensed after meteor ablation. Meteoric dust in bolides is occasionally deposited into the lower stratosphere around 20 km altitude. Nanometer CaO and pure carbon smoke particles were collected at 38 km altitude in the upper stratosphere in the Arctic during June 2008 using DUSTER (Dust in the Upper Stratosphere Tracking Experiment and Retrieval), a balloon-borne instrument for the non-destructive collection of solid particles between 200 nm to 40 microns. We report the collection of micron sized CaCO_3 (calcite) grains. Their morphologies show evidence of melting and condensation after vaporization suggest at temperatures of approximately 3500 K. The formation environment of the collected grains was probably a dense dust cloud formed by the disintegration of a carbonaceous meteoroid during deceleration in the Earth� atmosphere. For the first time, DUSTER collected meteor ablation products that were presumably associated with the disintegration of a bolide crossing the Earth's atmosphere. The collected mostly CaO and pure carbon nanoparticles from the debris cloud of a fireball, included: 1) intact fragments; 2) quenched melted grains; and 3) vapor phase condensation products. The DUSTER project was funded by the Italian Space Agency (ASI), PRIN2008/MIUR (Ministero dell'Istruzione dell'Universitá e della Ricerca), PNRA 2013(Piano Nazionale Ricerca Antartide). CNES graciously provided this flight opportunity. We thank E. Zona and S. Inarta at the Laboratorio di Fisica Cosmica INAF, Osservatorio Astronomico di Capodimonte-Universitá di Napoli Parthenope. F.J.M.R. was supported by grant NNX07AI39G from the NASA Cosmochemistry Program. We thank three anonymous reviewers who assisted us in introducing our new instrument.

  18. Origins of Water in the Solar System Leading to Habitable Worlds

    Science.gov (United States)

    Meech, Karen J.

    2015-08-01

    Life on Earth depends on an aqueous biochemistry, and water is a key component of habitability on Earth and for likely other habitable environments in the solar system. While water is ubiquitous in the interstellar medium, and plays a key role in protoplanetary disk chemistry, the inner solar system is relatively dry. We now have evidence for potentially thousands of extrasolar planets, dozens of which may be located in their host star’s habitable zones. Understanding how planets in the habitable zone accrete their water, is key to understanding the likelihood for habitability. Given that many disk models show that Earth formed inside the water-ice snow line of our solar system, understanding how the inner solar system received its water is important for understanding the potential for other planetary systems to host habitable worlds. Boundaries for the timing of the water delivery are constrained by cosmochemistry and geochemistry. Possible scenarios for the delivery of water to the inner solar system include adsorption on dust from protoplanetary disk gas, chemical reactions on the early earth, and delivery from planetesimals forming outside the water-ice snow line. This talk will set the stage for understanding the isotopic and geochemical markers along with the dynamical delivery mechanisms that will help uncover the origins of Earths water. This introduction will provide an overview for understanding the distribution of water in the solar system, in particular for the inner solar system and terrestrial planets—and the details will be developed in the subsequent talks. Additionally information will be presented regarding new inner solar system reservoirs of water that can shed light on origins (the main belt comets), and new research about water in the Earth.

  19. A Preliminary Study on Dust Grains in the Stratosphere

    Institute of Scientific and Technical Information of China (English)

    黄伯钧; 欧阳自远; 等

    1990-01-01

    Collected by means of a high-altitude scientific balloon and a self-made automatic sample collector,a total of 276 dust grains were selected for the study of shape,grain size and optical property.Some of the grains were examined by X-ray diffraction and electrom microprobe techniques,The stratospheric dust grains can be classified as 6 types:cosmic dusts,cosmic dusts(?),microtektite,natural pollutants,artificial pollutants and the unknown substances.The different types of dust grains have different characters and distinguishing symbols.Widespread in the space of the solar system,cosmic dusts are the initial substances of the solar system and ,to some degree,have recorded a great wealth of information on the early history of the solar system.So they have become one of the important objects in the field of cosmochemistry at present time,Since the 1960's,scholars of many countries have collected cosmic dusts both in the space near the earth(using rock ets,space probes and space shuttles)and in the stratosphere (using high-altitude balloons or U-2air planes).According to the shape(the scanning electron microimage),element composition(the energy-dispersive X-ray spectrum)and optical properties of dust grains,the substances in the stratosphere can be classified as 5 types:cosmic dusts,alumina spheroids,terrestrial artificial pollutants,terrestrial natural pollutants and unknown substances(CDPET,1982).

  20. Modification of REE distribution of ordinary chondrites from Atacama (Chile) and Lut (Iran) hot deserts: Insights into the chemical weathering of meteorites

    Science.gov (United States)

    Pourkhorsandi, Hamed; D'Orazio, Massimo; Rochette, Pierre; Valenzuela, Millarca; Gattacceca, Jérôme; Mirnejad, Hassan; Sutter, Brad; Hutzler, Aurore; Aboulahris, Maria

    2017-09-01

    The behavior of rare earth elements (REEs) during hot desert weathering of meteorites is investigated. Ordinary chondrites (OCs) from Atacama (Chile) and Lut (Iran) deserts show different variations in REE composition during this process. Inductively coupled plasma-mass spectrometry (ICP-MS) data reveal that hot desert OCs tend to show elevated light REE concentrations, relative to OC falls. Chondrites from Atacama are by far the most enriched in REEs and this enrichment is not necessarily related to their degree of weathering. Positive Ce anomaly of fresh chondrites from Atacama and the successive formation of a negative Ce anomaly with the addition of trivalent REEs are similar to the process reported from Antarctic eucrites. In addition to REEs, Sr and Ba also show different concentrations when comparing OCs from different hot deserts. The stability of Atacama surfaces and the associated old terrestrial ages of meteorites from this region give the samples the necessary time to interact with the terrestrial environment and to be chemically modified. Higher REE contents and LREE-enriched composition are evidence of contamination by terrestrial soil. Despite their low degrees of weathering, special care must be taken into account while working on the REE composition of Atacama meteorites for cosmochemistry applications. In contrast, chondrites from the Lut desert show lower degrees of REE modification, despite significant weathering signed by Sr content. This is explained by the relatively rapid weathering rate of the meteorites occurring in the Lut desert, which hampers the penetration of terrestrial material by forming voluminous Fe oxide/oxyhydroxides shortly after the meteorite fall.

  1. Canted Undulator Upgrade for GeoSoilEnviroCARS Sector 13 at the Advanced Photon Source

    Energy Technology Data Exchange (ETDEWEB)

    Sutton, Stephen

    2013-02-02

    Support for the beamline component of the canted undulator upgrade of Sector 13 (GeoSoilEnviroCARS; managed and operated by the University of Chicago) at the Advanced Photon Source (APS; Argonne National Laboratory) was received from three agencies (equally divided): NASA-SRLIDAP (now LARS), NSF-EAR-IF (ARRA) and DOE-Single Investigator Small Group (SISGR). The associated accelerator components (undulators, canted front end) were provided by the APS using DOE-ARRA funding. The intellectual merit of the research enabled by the upgrade lies in advancing our knowledge of the composition, structure and properties of earth materials; the processes they control; and the processes that produce them. The upgrade will facilitate scientific advances in the following areas: high pressure mineral physics and chemistry, non-crystalline and nano-crystalline materials at high pressure, chemistry of hydrothermal fluids, reactions at mineral-water interfaces, biogeochemistry, oxidation states of magmas, flow dynamics of fluids and solids, and cosmochemistry. The upgrade, allowing the microprobe to operate 100% of the time and the high pressure and surface scattering and spectroscopy instruments to receive beam time increases, will facilitate much more efficient use of the substantial investment in these instruments. The broad scientific community will benefit by the increase in the number of scientists who conduct cutting-edge research at GSECARS. The user program in stations 13ID-C (interface scattering) and 13ID-D (laser heated diamond anvil cell and large volume press) recommenced in June 2012. The operation of the 13ID-E microprobe station began in the Fall 2012 cycle (Oct.-Dec 2012). The upgraded canted beamlines double the amount of undulator beam time at Sector 13 and provide new capabilities including extended operations of the X-ray microprobe down to the sulfur K edge and enhanced brightness at high energy. The availability of the upgraded beamlines will advance the

  2. EURO-CARES: European Roadmap for a Sample Return Curation Facility and Planetary Protection Implications.

    Science.gov (United States)

    Brucato, John Robert

    2016-07-01

    A mature European planetary exploration program and evolving sample return mission plans gathers the interest of a wider scientific community. The interest is generated from studying extraterrestrial samples in the laborato-ry providing new opportunities to address fundamental issues on the origin and evolution of the Solar System, on the primordial cosmochemistry, and on the nature of the building blocks of terrestrial planets and on the origin of life. Major space agencies are currently planning for missions that will collect samples from a variety of Solar Sys-tem environments, from primitive (carbonaceous) small bodies, from the Moon, Mars and its moons and, final-ly, from icy moons of the outer planets. A dedicated sample return curation facility is seen as an essential re-quirement for the receiving, assessment, characterization and secure preservation of the collected extraterrestrial samples and potentially their safe distribution to the scientific community. EURO-CARES is a European Commission study funded under the Horizon-2020 program. The strategic objec-tive of EURO-CARES is to create a roadmap for the implementation of a European Extraterrestrial Sample Cu-ration Facility. The facility has to provide safe storage and handling of extraterrestrial samples and has to enable the preliminary characterization in order to achieve the required effectiveness and collaborative outcomes for the whole international scientific community. For example, samples returned from Mars could pose a threat on the Earth's biosphere if any living extraterrestrial organism are present in the samples. Thus planetary protection is an essential aspect of all Mars sample return missions that will affect the retrival and transport from the point of return, sample handling, infrastructure methodology and management of a future curation facility. Analysis of the state of the art of Planetary Protection technology shows there are considerable possibilities to define and develop

  3. Hydrogen cyanide polymers, comets and the origin of life.

    Science.gov (United States)

    Matthews, Clifford N; Minard, Robert D

    2006-01-01

    : ladder structures with conjugated -C=N- bonds and polyamidines readily converted by water to polypeptides. Thermochemolysis GC-MS studies show that cleavage products of the polymer include alpha-amino acids, nitrogen heterocycles such as purines and pyrimidines, and provide evidence for peptide linkages. Hydrogen cyanide polymers are a plausible link between cosmochemistry and the origin of informational macromolecules. Implications for prebiotic chemistry are profound. Following persistent bolide bombardment, primitive Earth may have been covered by water and carbonaceous compounds, particularly HCN polymers which would have supplied essential components for establishing protein/nucleic acid life.

  4. Short-lived radionuclide production by non-exploding Wolf-Rayet stars.

    Science.gov (United States)

    Arnould, M.; Paulus, G.; Meynet, G.

    1997-05-01

    This paper presents an extension and update of previous calculations of the production by non-exploding Wolf-Rayet stars of radionuclides that could be responsible for certain isotopic anomalies discovered in meteoritic inclusions, or in meteoritic grains of probable circumstellar origin. Quantitative predictions of the time dependence of the radionuclide composition of the wind of Wolf-Rayet stars with initial masses in the wide 25secure for Wolf-Rayet stars than for any other potential source of these species that has been contemplated up to now. This relates directly to the simplicity of these stars compared to highly difficult to model objects like Asymptotic Giant Branch stars, novae or supernovae. Our abundance predictions are confronted with existing observational data, or are hoped to help unravelling cases of potential interest for further laboratory quest when observations are lacking. The case of ^26^Al, of special interest for γ-ray line astronomy as well as for cosmochemistry, is also briefly revisited. In contrast to the other considered radionuclides, ^26^Al is produced during hydrogen burning, and is ejected at the WN evolutionary phase of the Wolf-Rayet stars. Our computed yields are also used as the basis for a qualitative discussion of the astrophysical plausibility of the contamination of the protosolar nebula with the radionuclides loading the Wolf-Rayet winds. Our calculations indicate that ^26^Al, ^41^Ca and ^107^Pd can be produced at a level compatible with the observations from a large variety of Wolf-Rayet stars with different masses and initial compositions. Wolf-Rayet stars could also account for the very uncertain limits set on (^36^Cl)_0_ and (^205^Pb)_0_. In addition, ^93^Zr, ^97^Tc, ^99^Tc and ^135^Cs are predicted to be produced in more or less large amounts, but the lack of secure experimental data prevents any meaningful confrontation with the observations. In contrast, the considered stars cannot explain the limits set recently

  5. Isotope U-Pb age on single zircon and REE distribution in rocks and zircon from paleoproterozoic Kandalaksha-Kolvitsa complex Baltic shield

    Science.gov (United States)

    Steshenko, Ekaterina; Bayanova, Tamara; Drogobuzhskaya, Svetlana; Lyalina, Ludmila; Serov, Pavel; Chashchin, Viktor; Elizarov, Dmitriy

    2017-04-01

    -05-00305, 16-05-00367, 16-05-00427) and theme of state assignment № 0231-2015-0005. References: 1. Boynton W.V. Cosmochemistry of the rare earth elements: meteorite studies // Ed. Henderson P. Rare earth element geochemistry. Amsterdam: Elsevier. 1984. P. 63-114. 2. Watson E. B., Wark D.A., Thomas J.B. Crystallization thermometers for zircon and rutile // Contrib. Miner. Petrol. 2006. V. 151. P. 413-433. 3. Hoskin P.W.O. and Schaltegger U. The Composition of zirconand igneous and metamorphic petrogenesis // Reviews in mineralogy & geochemistry. 2003. V. 53. P. 27-62.

  6. Rare Earth elements as sediment tracers in Mangrove ecosystems

    Science.gov (United States)

    Ramanathan, A. L.; Swathi, S.

    2013-05-01

    Rare earth elements have been widely used as geochemical source fingerprints of rocks and sediments to study processes involving cosmo-chemistry, igneous petrology, tectonic setting and for investigations of water-rock interactions and weathering processes including transport of weathering products to the oceans.Many studies have addressed the use of REEs in investigating the environmental impact of human activity and demonstrated that the REE natural distribution in sediment from densely industrialised and populated regions can be altered by anthropogenic influences.The coastal wetlands like Mangroves are ultimate sinks for all the material derived from the terrestrial and marine environment.The high productivity and low ratio of sediment respiration to net primary production gives mangrove sediments the potential for long-term sequestration of these pollutants/metals before reaching the coastal ocean. Geochemical study of REE in these sedimentary systems is useful for determining the nature of the biogeochemical processes. In particular, REE show a great sensitivity to pH changes, redox conditions and adsorption/ desorption reactions. So, they may be used as markers of discharge provenance, weathering processes, changes in environmental conditions in the water and sediments of Mangrove/wetland systems. Our study aims to establish the abundance, distribution and enrichment of REEs to track the sediment sources and biogeochemical processes occurring in the mangrove environment.Core sediments were collected from the different environmental settings within the Pichavaram mangrove area.Higher REE concentration in Pichavaram sediments indicated greater input from sources like terrestrial weathering and anthropogenic activities which in turn are affected by saline mixing and dynamic physico-chemical processes occurring in the mangrove environment. REE enrichment order was attributed to the alkaline pH (7-8.5) and reducing conditions prevailing in the mangrove

  7. The distribution of uranium over Europe: Geological and environmental significance

    Science.gov (United States)

    Plant, J.A.; Reeder, S.; Salminen, R.; Smith, D.B.; Tarvainen, T.; de Vivo, B.; Petterson, M.G.

    2003-01-01

    The variation of baseline levels of uranium in soil and stream sediments over Europe is described, based on new data prepared by the Forum of European Geological Surveys (FOREGS). The samples have been collected and analysed according to the protocols established for the International Union of Geological Sciences/International Association of Geochemistry and Cosmochemistry (IUGS/IAGC) Working Group on Global Geochemical Baselines. The baseline levels of U vary between 0??21 to 53 mg kg-1 in topsoils, 0??19 to 30 mg kg-1 in subsoils and < 1 to 59 mg kg-1 in stream sediments. There is generally good agreement between the levels of U in the three sample types, and the median concentration in all three media is approximately 2 mg kg-1. The most anomalous baseline levels occur over the Variscan orogen, especially areas into which late post-orogenic radiothermal high heat production (HHP) granites were emplaced. Spiderdiagrams based on trace element levels and rare earth element (REE) plots, confirm the association between the highest U anomalies and evolved radiothermal granites. High values are also associated with parts of the Alpine terrain especially in Slovenia, where there are historical U workings, and Southern Italy, where high values of U reflect contemporary volcanism. In contrast, much of the Caledonides of North West Europe and the Precambrian of the Baltic Shield and East European craton and its overlying sedimentary cover have very low values, generally < 4 mg kg-1. The results suggest that the main concern for the environment and human health from U, and the Th and K with which it is generally associated, is the naturally occurring total gamma radiation and radon potential associated with radiothermal granites. This is likely to be especially important where the granites are mineralised and have been worked historically, for example in the North West of the Iberian Peninsula where U and its decay products are likely to be more dispersed in the surface

  8. Europlanet Research Infrastructure: Planetary Sample Analysis Facilities

    Science.gov (United States)

    Cloquet, C.; Mason, N. J.; Davies, G. R.; Marty, B.

    2008-09-01

    EuroPlanet The Europlanet Research Infrastructure consortium funded under FP7 aims to provide the EU Planetary Science community greater access for to research infrastructure. A series of networking and outreach initiatives will be complimented by joint research activities and the formation of three Trans National Access distributed service laboratories (TNA's) to provide a unique and comprehensive set of analogue field sites, laboratory simulation facilities, and extraterrestrial sample analysis tools. Here we report on the infrastructure that comprises the third TNA: Planetary Sample Analysis Facilities. The modular infrastructure represents a major commitment of analytical instrumentation by three institutes and together forms a state-of-the-art analytical facility of unprecedented breadth. These centres perform research in the fields of geochemistry and cosmochemistry, studying fluids and rocks in order to better understand the keys cof the universe. Europlanet Research Infrastructure Facilities: Ion Probe facilities at CRPG and OU The Cameca 1270 Ion microprobe is a CNRS-INSU national facility. About a third of the useful analytical time of the ion probe (about 3 months each year) is allocated to the national community. French scientists have to submit their projects to a national committee for selection. The selected projects are allocated time in the following 6 months twice a year. About 15 to 20 projects are run each year. There are only two such instruments in Europe, with cosmochemistry only performed at CRPG. Different analyses can be performed on a routine basis, such as U-Pb dating on Zircon, Monazite or Pechblende, Li, B, C, O, Si isotopic ratios determination on different matrix, 26Al, 60Fe extinct radioactivity ages, light and trace elements contents . The NanoSIMS 50L - producing element or isotope maps with a spatial resolution down to ≈50nm. This is one of the cornerstone facilities of UKCAN, with 75% of available instrument time funded and

  9. ARES Biennial Report 2012 Final

    Science.gov (United States)

    Stansbery, Eileen

    2014-01-01

    , which relies on access to the samples. The curation efforts are greatly enhanced by a strong group of planetary scientists who conduct peerreviewed astromaterials research. Astromaterials Research Office scientists conduct peer-reviewed research as Principal or Co-Investigators in planetary science (e. g., cosmochemistry, origins of solar systems, Mars fundamental research, planetary geology and geophysics) and participate as Co-Investigators or Participating Scientists in many of NASA's robotic planetary missions. Since the last report, ARES has achieved several noteworthy milestones, some of which are documented in detail in the sections that follow. Within the Human Exploration Science Office, ARES is a world leader in orbital debris research, modeling and monitoring the debris environment, designing debris shielding, and developing policy to control and mitigate the orbital debris population. ARES has aggressively pursued refinements in knowledge of the debris environment and the hazard it presents to spacecraft. Additionally, the ARES Image Science and Analysis Group has been recognized as world class as a result of the high quality of near-real-time analysis of ascent and on-orbit inspection imagery to identify debris shedding, anomalies, and associated potential damage during Space Shuttle missions. ARES Earth scientists manage and continuously update the database of astronaut photography that is predominantly from Shuttle and ISS missions, but also includes the results of 40 years of human spaceflight. The Crew Earth Observations Web site (http://eol.jsc.nasa.gov/Education/ESS/crew.htm) continues to receive several million hits per month. ARES scientists are also influencing decisions in the development of the next generation of human and robotic spacecraft and missions through laboratory tests on the optical qualities of materials for windows, micrometeoroid/orbital debris shielding technology, and analog activities to assess surface science operations. ARES

  10. The Sulfur Cycle at Subduction Zones

    Science.gov (United States)

    de Moor, M. J.; Fischer, T. P.; Sharp, Z. D.

    2013-12-01

    of the flux of S released from slab into the mantle wedge. Based on these constraints, we calculate that 1.2 × 0.4 x 1010 mols of S/yr is released from the slab. If slab-derived S is in the S6+ oxidation state, this flux is enough to oxidize the entire mantle wedge to the Fe3+/Fe2+ observed in typical arc rocks in ~ 20 million years. [1] Hilton et al. (2002) Noble Gases in Geochemistry and Cosmochemistry. pp. 319-370 [2] de Moor et al., (in review) G-cubed [3] Rowe (1994) Chem. Geol., 236:303-322 [4] Sakai et al. (1984) J. Petrol., 52: 1307-1331 [5] Alt et al. (2012) Earth Plan. Sci. Lett., 327: 50-60

  11. Feasibility of Iodine and Bromine analysis in Genesis AloS collectors

    Science.gov (United States)

    Pravdivtseva, O.; Meshik, A.; Hohenberg, C. M.; Burnett, D. S.

    2011-12-01

    reduced surface contamination, it did not affect iodine and bromine associated with the interface. Thus, cleaner Si-based Genesis collectors could be more suitable for SW halogen analyses. Our first results suggest that determination of solar iodine and bromine is potentially feasible, considering the possibility of analyzing larger collector areas irradiated with higher neutron fluence in order to improve counting statistics of the measurements. Supported by NASA grant NNX07AM76G. [1] Anders E. and Ebihara M. 1982. GCA 46:2363-2380. [2] Anders E. and Grevesse N. 1989. GCA 53:197-214. [3] Cameron A. G. W. 1968. in Origin and distribution of the elements (Ahrens L. H., ed.), Pergamon, Oxford:125-143. [4] Cameron A. G. W. 1973. Space Science Revues 15:121-146. [5] Suess H. E. and Urey H. C. 1956. Revisions of Modern Physics 28:53-74. [6] Lodders K. 2010. in: Principles and Perspectives in Cosmochemistry. 379-417. [7] Meshik A. et all. 2011. 74th Meteoritical Society Meeting, Abstract#5471.

  12. HCN Polymers: Toward Structure Comprehension Using High Resolution Mass Spectrometry

    Science.gov (United States)

    Bonnet, Jean-Yves; Thissen, Roland; Frisari, Ma; Vuitton, Veronique; Quirico, Eric; Le Roy, Léna; Fray, Nicolas; Cottin, Hervé; Horst, Sarah; Yelle, Roger

    derive quantitative and qualitative parameters, (H/C, N/C ratios for exemple). [1] D. P. Cruikshank, H. Imanaka, and C. M. Dalle Ore. Tholins as coloring agents on outer Solar System bodies. Advances in Space Research, 36:178-183, 2005. [2] H. Cottin and N. Fray. Distributed Sources in Comets. Space Science Reviews, 138:179-197, July 2008. [3] J. Kissel, R. Z. Sagdeev, J. L. Bertaux, V. N. Angarov, J. Audouze, J. E. Blamont, K. Buchler, E. N. Evlanov, H. Fechtig, M. N. Fomenkova, H. von Hoerner, N. A. Inogamov, V. N. Khromov, W. Knabe, F. R. Krueger, Y. Langevin, B. Leonasv, A. C. Levasseur-Regourd, G. G.Managadze, S. N. Podkolzin, V. D. Shapiro, S. R. Tabaldyev, and B. V. Zubkov. Com-position of comet Halley dust particles from VEGA observations. Nature, 321:280-282, May 1986. [4] D. Despois, J. Crovisier, D. Bockelee-Morvan, E. Gerard, and J. Schraml. Observations of hydrogen cyanide in comet halley. Astronomy and Astrophysics, 160:L11+, May 1986. [5] C. N. Matthews and R. D. Minard. Hydrogen cyanide polymers connect cosmochemistry and biochemistry. In IAU Symposium, volume 251 of IAU Symposium, pages 453-458, October 2008. [6] N. Sarker, A. Somogyi, J. I. Lunine, and M. A. Smith. Titan Aerosol Analogues: Analysis of the Nonvolatile Tholins. Astrobiology, 3:719-726, December 2003.

  13. I-Xe Dating of Small Chondrules from the Bjurbole Meteorite Using RELAX

    Science.gov (United States)

    Whitby, J. A.; Gilmour, J. D.; Ash, R. D.; Turner, G.

    1995-09-01

    the plateau. The reason for this is unclear, although the presence in the sample of material with an older closure age is a possible explanation and may account for the observed spread in I-Xe ages of Bjurbole chondrules. Two of the chondrules analysed (ABjC33, ABjC22) exhibited a good correlation between excess 128Xe and 131Xe, in agreement with some prior observations [2,3], suggesting that in some chondrules the iodine bearing phase may be intimately mixed with a phase containing barium or tellurium. Aliquots of all the chondrules analysed have been retained for mineralogical characterization. References: [1] Turner G. (1965) JGR, 70, 5433-5445. [2] Gilmour J. D. et al. (1995) Meteoritics, in press. [3] Gilmour J. D. and Turner G. (1994) Noble Gas Geochemistry and Cosmochemistry (J. Matsuda, ed.). [4] Gilmour J. D. et al. (1994) Rev. Sci. Instrum., 65, 617-625. [5] Caffee et al. (1982) Proc. LPSC 13th, in JGR, 87, A303-A317. [6] Lavielle B. and Marti K. (1992) JGR, 97, 20875-20881.

  14. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 1996 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Ryerson, F. J., Institute of Geophysics and Planetary Physics

    1998-03-23

    The Institute of Geophysics and Planetary Physics (IGPP) is a Multicampus Research Unit of the University of California (UC). IGPP was founded in 1946 at UC Los Angeles with a charter to further research in the earth and planetary sciences and in related fields. The Institute now has branches at UC campuses in Los Angeles, San Diego, and Riverside, and at Los Alamos and Lawrence Livermore national laboratories. The University-wide IGPP has played an important role in establishing interdisciplinary research in the earth and planetary sciences. For example, IGPP was instrumental in founding the fields of physical oceanography and space physics, which at the time fell between the cracks of established university departments. Because of its multicampus orientation, IGPP has sponsored important interinstitutional consortia in the earth and planetary sciences. Each of the five branches has a somewhat different intellectual emphasis as a result of the interplay between strengths of campus departments and Laboratory programs. The IGPP branch at Lawrence Livermore National Laboratory (LLNL) was approved by the Regents of the University of California in 1982. IGPP-LLNL emphasizes research in seismology, geochemistry, cosmochemistry, and astrophysics. It provides a venue for studying the fundamental aspects of these fields, thereby complementing LLNL programs that pursue applications of these disciplines in national security and energy research. IGPP-LLNL is directed by Charles Alcock and was originally organized into three centers: Geosciences, stressing seismology; High-Pressure Physics, stressing experiments using the two-stage light-gas gun at LLNL; and Astrophysics, stressing theoretical and computational astrophysics. In 1994, the activities of the Center for High-Pressure Physics were merged with those of the Center for Geosciences. The Center for Geosciences, headed by Frederick Ryerson, focuses on research in geophysics and geochemistry. The Astrophysics Research

  15. Accounting for Recoil Effects in Geochronometers: A New Model Approach

    Science.gov (United States)

    Lee, V. E.; Huber, C.

    2012-12-01

    A number of geologically important chronometers are affected by, or owe their utility to, the "recoil effect". This effect describes the physical displacement of a nuclide due to energetic nuclear processes such as radioactive alpha decay (as in the case of various parent-daughter pairs in the uranium-series decay chains, and Sm-Nd), as well as neutron irradiation (in the case of the methodology for the 40Ar/39Ar dating method). The broad range of affected geochronometers means that the recoil effect can impact a wide range of dating method applications in the geosciences, including but not limited to: Earth surface processes, paleoclimate, volcanic processes, and cosmochemistry and planetary evolution. In particular, the recoil effect can have a notable impact on the use of fine grains (silt- and clay-sized particles) for geochronometric dating purposes. This is because recoil-induced loss of a nuclide from the surfaces of a grain can create an isotopically-depleted outer rind, and for small grains, this depleted rind can be volumetrically significant. When this recoil loss is measurable and occurs in a known time-dependent fashion, it can usefully serve as the basis for chronometers (such as the U-series comminution age method); in other cases recoil loss from fine particles creates an unwanted deviation from expected isotope values (such as for the Ar-Ar method). To improve both the accuracy and precision of ages inferred from geochronometric systems that involve the recoil of a key nuclide from small domains, it is necessary to quantify the magnitude of the recoil loss of that particular nuclide. It is also necessary to quantitatively describe the effect of geological processes that can alter the outer surface of grains, and hence the isotopically-depleted rind. Here we present a new mathematical and numerical model that includes two main features that enable enhanced accuracy and precision of ages determined from geochronometers. Since the surface area of the

  16. Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, 1996 Annual Report

    Energy Technology Data Exchange (ETDEWEB)

    Ryerson, F. J., Institute of Geophysics and Planetary Physics

    1998-03-23

    The Institute of Geophysics and Planetary Physics (IGPP) is a Multicampus Research Unit of the University of California (UC). IGPP was founded in 1946 at UC Los Angeles with a charter to further research in the earth and planetary sciences and in related fields. The Institute now has branches at UC campuses in Los Angeles, San Diego, and Riverside, and at Los Alamos and Lawrence Livermore national laboratories. The University-wide IGPP has played an important role in establishing interdisciplinary research in the earth and planetary sciences. For example, IGPP was instrumental in founding the fields of physical oceanography and space physics, which at the time fell between the cracks of established university departments. Because of its multicampus orientation, IGPP has sponsored important interinstitutional consortia in the earth and planetary sciences. Each of the five branches has a somewhat different intellectual emphasis as a result of the interplay between strengths of campus departments and Laboratory programs. The IGPP branch at Lawrence Livermore National Laboratory (LLNL) was approved by the Regents of the University of California in 1982. IGPP-LLNL emphasizes research in seismology, geochemistry, cosmochemistry, and astrophysics. It provides a venue for studying the fundamental aspects of these fields, thereby complementing LLNL programs that pursue applications of these disciplines in national security and energy research. IGPP-LLNL is directed by Charles Alcock and was originally organized into three centers: Geosciences, stressing seismology; High-Pressure Physics, stressing experiments using the two-stage light-gas gun at LLNL; and Astrophysics, stressing theoretical and computational astrophysics. In 1994, the activities of the Center for High-Pressure Physics were merged with those of the Center for Geosciences. The Center for Geosciences, headed by Frederick Ryerson, focuses on research in geophysics and geochemistry. The Astrophysics Research

  17. A Review of the International Geochemical Conference: Goldschmidt 2011%国际地球化学研究现状与发展前沿——国际地球化学大会Goldschmidt2011印象

    Institute of Scientific and Technical Information of China (English)

    罗立强

    2012-01-01

    On the basis of Goldschmidt 2011, the advantages of geochemistry research are reviewed in three separate parts. The first parts is a review of five plenary presentations, which includes mainly volatiles in the mantle and deep earth, the last deglaciation and its impact on rivers, exoplanet atmospheres, microbial partnerships and methane-oxidation in deep sea. The second part has 23 themes, which mainly includes cosmochemistry, planet and earth formation, evolution and dynamics of the deep earth, ocean ridge and intraplate volcanism, continental crust formation and evolution, evolution of the earth's environment, interfaces and interfacial processes from the nano- to the continental scale, climate change, atmospheric aerosols, oceans atmosphere, and geochemical impacts of human activity; the main research fields in each theme are described briefly. The subject matter for the third part of the review is biogeochemistry, in which biogeochemical cycling, organic matter turnover, methane cycling in marine and terrestrial environments, microbial catalysis of mineral dissolution and precipitation, bioavailability of trace elements in contaminated environments, biogeochemical processes in redox-dominated environments are the focus for discussion.%对国际地球化学大会Goldschmidt 2011的基本情况、5个大会主题报告和23个分会报告作了较详细介绍与评述.这5个大会主题报告是:地幔中的挥发组分对板内岩浆作用的影响,地球深部挥发组分的循环:从远古到现代,利用地球化学信息研究末次冰川消退及其对河流的影响,外星大气:一个由热到可居住的世界,深海中的微生物群落与甲烷氧化作用.23个分会报告包括:宇宙化学,行星形成;早期地球:从地核到大气;地球深部动力学及其演化;从地幔至地壳:洋脊与板内岩浆活动;大陆壳的形成及演化;循环:俯冲,地幔楔与弧火山作用;地球环境演化;从纳米到大陆尺度界面与界面过程;

  18. Models of Ceres' Surface as a Function of Origin and Evolution Scenarios

    Science.gov (United States)

    Castillo, J. C.; Frank, E.; Grazier, K.; Raymond, C. A.

    2012-12-01

    After its spectacular encounter with Vesta, the Dawn spacecraft is now on its way to the largest object in the main belt, Ceres. The last few years have seen a growing interest in the origin and evolution of this object and increased observational constraints on its geophysical properties and surface chemistry. In 2005, McCord and Sotin (2005) introduced the idea that Ceres could have held a deep ocean for some period of time. Rivkin (2006) discovered carbonates at the surface of Ceres, evidence for chemistry in aqueous environments, an idea reinforced by and Milliken and Rivkin's (2009) suggestion that brucite is a major component of Ceres' surface. See also Rivkin et al. (this conference) for the state of the art on Ceres' surface composition inferred from astronomical observations. In parallel, recent developments in Solar system dynamical evolution (Walsh et al. 2011; Grazier et al. 2012) and cosmochemistry models (Dodson-Robinson et al. 2009) and measurements (d'Alexander et al. 2012) indicate that asteroid volatiles may have been supplied from different sources and included second-phase low-eutectic impurities such as ammonia hydrates. Hence, the upcoming rendezvous of Dawn at Ceres offers the prospect of obtaining constraints on the origin of volatiles in the main belt and the habitability potential of large wet asteroids such as Ceres. Ceres' surface chemistry is the product of multiple parameters and processes: (1) the composition of accreted materials, volatile composition, and the possibility for hydrothermal activity in planetesimals prior to accretion in Ceres (i.e., in objects of the size of chondrite parent bodies); (2) evolution of the rock and ocean chemistry as a consequence of one or several episodes of hydrothermal activity (Castillo-Rogez and McCord 2010), (3) the transportation mechanism that may encompass solid-state convection or cryovolcanism and act as a possible filter against certain species in the ocean; (4) exogenic processing (esp. UV

  19. Foreword

    Science.gov (United States)

    Jorissen, A.; Goriely, S.; Rayet, M.; Siess, L.; Boffin, H.

    performed using a radioactive ion beam technique, a new and powerful tool of investigation in nuclear astrophysics, which has since been developed worldwide. The second program, “Nuclear Astrophysics: measurement, evaluation and compilation of reaction rates, and their impact on stellar evolution and nucleosynthesis" (1992 1997), gave the scientific community the first European compilation of astrophysical reaction rates. This work was meant to supersede the compilations performed during more than forty years by a team led by the late Nobel Prize winner, William A. Fowler, at the California Institute of Technology. A relentless scientific advisor amongst astrophysicists as well as nuclear physicists, Marcel deplores the persistent lack of communication between those two communities. For years, his hope has been to see the rise of a generation of true astronuclear physicists, but one has to admit with him that this goal is far from being achieved yet and that one still has to fight, despite all the expressions of good intentions, against the barriers that, as is usual, separate scientific disciplines. It is therefore in tribute to the transdisciplinary and visionary nature of Marcel Arnould's scientific work that his close collaborators at the IAA decided to organize this conference, which is explicitely devoted to future developments in the field of astronuclear physics and not, as is often the case, to already completed, or even published, works. The audience has been limited from the start to invited participants chosen for the quality of their human and scientific relations with Marcel, as well as for their contribution to the domains he is exceptionally found of. The conference program was on purpose centered on a few fields that for many years now have been central to the activities of the IAA: the stellar nucleosynthesis and its relations to stellar physics, to nuclear physics and to cosmochemistry. The organizers' choice was to concentrate on a few challenging

  20. High Precision 142Nd/144Nd and 143Nd/144Nd Isotope Ratio Measurements in Rock Samples

    Science.gov (United States)

    Ali, A.; Srinivasan, G.

    2009-05-01

    The long-lived 147Sm-143Nd system with a half-life (T1/2) of 106 Gyr is generally used for geochronology. The short-lived 146Sm-142Nd system (T1/2= 103 Myr) is used as a geological tracer to track early (˜500 Ma) silicate differentiation [1] events in different planetary bodies. The isotope composition measurements by thermal ionization mass spectrometry (TIMS) require purification of Nd using chemical separation methods. This is important as an impure sample will give both a very poor ion yield and cause beam instability in the mass spectrometer, potentially resulting in a poor analysis [2]. The separation of Nd for 143Nd isotope measurement is, fairly straightforward because there is no isobaric interference of any other REE. While 142Nd isotope analysis needs chemically separated Nd fraction to be ˜100% Ce-free as latter is composed of a substantial amount of 142Ce isotope. A 4-steps technique, modified from Caro et al., [3], for the separation of Nd is established at the Cosmochemistry Laboratory of University of Toronto, Canada and applied to the measurement of Nd isotope ratios in geological reference sample BCR-2 (USGS, Columbia River basalt) using TIMS. Results of the isotopic ratios obtained for BCR-2 are in good agreement with published values [e.g., 4]. Analytical work on the samples discovered as the oldest rocks on Earth [5] from Nuvvuagittuq greenstone belt in Québec, Canada and various meteorites is in progress. An account of the procedures involved is briefly described here. All working solutions and acids were prepared using >18.2 MΩ.cm-1 H2O from a Milli-Q water system. Experiments were performed under Class 100 clean work bench with acid-cleaned apparatus and plastic-ware. The whole rock powders were weighed (20-30 mg) and dissolved in a mixture of HF and HNO3 using PFA vials and heated at 110°C. Further decomposition was done in Teflon bomb in the oven at 205°C. Later on contents of the Teflon bomb were transferred to vials and fluorides

  1. Uranium isotopic compositions of the crust and ocean: Age corrections, U budget and global extent of modern anoxia

    Science.gov (United States)

    Tissot, François L. H.; Dauphas, Nicolas

    2015-10-01

    the variability of the 238U/235U ratio on Pb-Pb and U-Pb ages and provide analytical formulas to calculate age corrections as a function of the age and isotopic composition of the sample. The crustal ratio may be used in calculation of Pb-Pb and U-Pb ages of continental crust rocks and minerals when the U isotopic composition is unknown. In cosmochemistry, the search for 247Cm (t1/2 = 15.6 Myr), an extinct short-lived radionuclide that decays into 235U, is important for understanding how r-process nuclides were synthesized in stars and learning about the astrophysical context of solar system formation (Chen and Wasserburg, 1981; Wasserburg et al., 1996; Nittler and Dauphas, 2006; Brennecka et al., 2010b; Tissot et al., 2015). In both terrestrial and extraterrestrial samples, variations in the 238U/235U ratio affect Pb-Pb ages (and depending on the analytical protocols, U-Pb ages). Therefore, samples dated by these techniques need to have their U isotopic compositions measured (Stirling et al., 2005, 2006; Weyer et al., 2008; Amelin et al., 2010; Brennecka et al., 2010b; Brennecka and Wadhwa, 2012; Connelly et al., 2012; Goldmann et al., 2015) or uncertainties on the U isotopic composition should be propagated into age calculations. In low temperature aqueous geochemistry, U isotopic fractionation between U4+ and U6+ (driven in part by nuclear field shift effects; Bigeleisen, 1996; Schauble, 2007; Abe et al., 2008), makes U isotopes potential tracers of paleoredox conditions (Montoya-Pino et al., 2010; Brennecka et al., 2011a; Kendall et al., 2013, 2015; Asael et al., 2013; Andersen et al., 2014; Dahl et al., 2014; Goto et al., 2014; Noordmann et al., 2015). The present paper aims at constraining some aspects of the global budget of uranium in the modern oceans using 238U/235U isotope variations, which involves characterizing the U isotopic composition of seawater and several reservoirs involved in the uranium oceanic budget. Uranium can exist in two oxidation states

  2. Science at the ends of the Earth: astrobiology field expeditions as outreach tools

    Science.gov (United States)

    Billings, Linda

    paper will report on and evaluate communication, education, and outreach initiatives conducted in conjunction with ASTEP field campaigns, addressing the costs and benefits of linking students, teachers, and other interested citizens with researchers in the field. This paper will highlight success stories, lessons learned, and promising practices regarding educational programs in scientific research environments. SUMMARY The Astrobiology Program in NASA's Science Mission Directorate studies the origin, evolution, distribution, and future of life in the universe. Astrobiology research addresses three fundamental questions: How does life begin and evolve? Is there life beyond Earth and how can we detect it? What is the future of life on Earth and in the universe? Goals of the Astrobiology Program range from determining the nature and distribution of habitable environments in the Solar System and beyond to understanding the emergence of life from cosmic and planetary precursors, the interaction of past life on Earth with its changing environment, the formation and evolution of planets, links between planetary and biological evolution, the effects of climate and geology on habitability, and life's precursors and habitats in the outer solar system. Research dedicated to fulfilling these goals is conducted on Earth and in space, with a growing number of astrobiology investigations flying on planetary exploration missions. The field of astrobiology is an endeavor that brings together researchers in a broad range of disciplines including Earth and planetary science, astrophysics, heliophysics, microbiology and evolutionary biology, and cosmochemistry. Since 1995, the field of astrobiology has grown rapidly, and the pace of discovery has been brisk. The possibility of extraterrestrial life is now a serious scientific question. Research findings over the past decade that are relevant to this question include the controversial 1996 claim of fossil evidence for microbial life in a

  3. The narrative power of astrobiology

    Science.gov (United States)

    Billings, Linda

    The narrative power of astrobiology: Telling the story of the quest to understand life's origins and the search for evidence of extraterrestrial life INTRODUCTION The story of the origins and evolution of life is a narrative with nearuniversal appeal. The story of life on Earth is meaningful to all people, and the search for life elsewhere is appealing across cultural boundaries. The U.S. National Aeronautics and Space Administration (NASA) funds an Astrobiology Program in NASA's Science Mission Directorate that is dedicated to the study of the origin, evolution, distribution, and future of life in the universe. Because public interest in astrobiology is great and advances in the field are rapid, the NASA Astrobiology Program aims to integrate communication, education, and outreach into all aspects of program planning and execution. This strategic approach to communication is intended to promote the widest possible dissemination of timely and useful information about scientific discoveries, technology development, new knowledge, and greater understanding produced by the Astrobiology Program. This paper will address how scientists in the field of astrobiology can participate in the telling of an ongoing story of interest to multicultural audiences and why it is important to tell this story. SUMMARY Astrobiology research addresses three fundamental questions: How does life begin and evolve? Is there life beyond Earth and how can we detect it? What is the future of life on Earth and in the universe? The field of astrobiology is an endeavor that brings together researchers in a broad range of disciplines including Earth and planetary science, astrophysics, heliophysics, microbiology and evolutionary biology, and cosmochemistry. Goals of the NASA Astrobiology Program range from determining the nature and distribution of habitable environments in the Solar System and beyond to understanding the emergence of life from cosmic and planetary precursors, the interaction of

  4. Terrestrial microbes in martian and chondritic meteorites

    Science.gov (United States)

    Airieau, S.; Picenco, Y.; Andersen, G.

    2007-08-01

    NASA Cosmochemistry grant, ( P. I. Thiemens).