A Abyssal Impact Structure 61 Accelerator Mass Spectrometry
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
THE PLANETARY REPORT DECEMBER SOLSTICE 2016 VOLUME 36, NUMBER 4 Planetary.Org
THE PLANETARY REPORT DECEMBER SOLSTICE 2016 VOLUME 36, NUMBER 4 planetary.org A PEAK YEAR 2016 YEAR IN PICTURES PRESERVING OUR PAST C ROCKET ROAD TRIP C CALLING CHARTER MEMBERS Calling All Charter Members Envisioning a New Outreach Program A PLANETARY SOCIETY charter member is a I contacted Robin Young, the Society’s person whose membership began in 1980 or donor relations coordinator, and we began TOP LEFT A special evening reception and 1981 and who remains active today. We charter an e-mail dialog that led to a conference call fundraiser opened The members have a long-term perspective about between Robin, Society Chief Development Planetary Society’s The Planetary Society and the importance of Officer Richard Chute, and myself. We brain- 35th Anniversary its ongoing goals and plans, and we can be stormed on potential ways in which charter celebrations on October a power base of talent, ability, and ideas for members, working together under the direc- 23, 2015. At Pasadena’s the Society. However, there has not been a tion and guidance of a Planetary Society staff famed Huntington Library, cofounder format for us to organize and work together member, could make a wide variety of impor- Louis D. Friedman on projects for The Planetary Society. tant contributions. told stories about The At the Society’s 35th Anniversary celebra- The concept is nebulous at this point, but Planetary Society’s tions in Pasadena last year, several of us charter we would like to know whether the general inception and early members got acquainted and our conversa- idea of a task force of charter members days to our charter members, friends, tions almost always led to our remembrances working together on a project appeals to you. -
Disequilibrium Melting and Melt Migration Driven by Impacts: Implications for Rapid Planetesimal Core Formation
Available online at www.sciencedirect.com Geochimica et Cosmochimica Acta 100 (2013) 41–59 www.elsevier.com/locate/gca Disequilibrium melting and melt migration driven by impacts: Implications for rapid planetesimal core formation Andrew G. Tomkins ⇑, Roberto F. Weinberg, Bruce F. Schaefer 1, Andrew Langendam School of Geosciences, P.O. Box 28E, Monash University, Melbourne, Victoria 3800, Australia Received 20 January 2012; accepted in revised form 24 September 2012; available online 12 October 2012 Abstract The e182W ages of magmatic iron meteorites are largely within error of the oldest solar system particles, apparently requir- ing a mechanism for segregation of metals to the cores of planetesimals within 1.5 million years of initial condensation. Cur- rently favoured models involve equilibrium melting and gravitational segregation in a static, quiescent environment, which requires very high early heat production in small bodies via decay of short-lived radionuclides. However, the rapid accretion needed to do this implies a violent early accretionary history, raising the question of whether attainment of equilibrium is a valid assumption. Since our use of the Hf–W isotopic system is predicated on achievement of chemical equilibrium during core formation, our understanding of the timing of this key early solar system process is dependent on our knowledge of the seg- regation mechanism. Here, we investigate impact-related textures and microstructures in chondritic meteorites, and show that impact-generated deformation promoted separation of liquid FeNi into enlarged sulfide-depleted accumulations, and that this happened under conditions of thermochemical disequilibrium. These observations imply that similar enlarged metal accumu- lations developed as the earliest planetesimals grew by rapid collisional accretion. -
Planetary Defence Activities Beyond NASA and ESA
Planetary Defence Activities Beyond NASA and ESA Brent W. Barbee 1. Introduction The collision of a significant asteroid or comet with Earth represents a singular natural disaster for a myriad of reasons, including: its extraterrestrial origin; the fact that it is perhaps the only natural disaster that is preventable in many cases, given sufficient preparation and warning; its scope, which ranges from damaging a city to an extinction-level event; and the duality of asteroids and comets themselves---they are grave potential threats, but are also tantalising scientific clues to our ancient past and resources with which we may one day build a prosperous spacefaring future. Accordingly, the problems of developing the means to interact with asteroids and comets for purposes of defence, scientific study, exploration, and resource utilisation have grown in importance over the past several decades. Since the 1980s, more and more asteroids and comets (especially the former) have been discovered, radically changing our picture of the solar system. At the beginning of the year 1980, approximately 9,000 asteroids were known to exist. By the beginning of 2001, that number had risen to approximately 125,000 thanks to the Earth-based telescopic survey efforts of the era, particularly the emergence of modern automated telescopic search systems, pioneered by the Massachusetts Institute of Technology’s (MIT’s) LINEAR system in the mid-to-late 1990s.1 Today, in late 2019, about 840,000 asteroids have been discovered,2 with more and more being found every week, month, and year. Of those, approximately 21,400 are categorised as near-Earth asteroids (NEAs), 2,000 of which are categorised as Potentially Hazardous Asteroids (PHAs)3 and 2,749 of which are categorised as potentially accessible.4 The hazards posed to us by asteroids affect people everywhere around the world. -
The Planetary Report, to Make Those Discoveries Acces 20 Questions and Sible to All of Our Members
- --_.- .. .. _-- The Volume XIV On the Cover : Skywatchers will be poised to observe the heavenly Table of Number 1 stri ng of pearls kn own as comet Shoemaker-Levy 9 January/February 1994 thi s July when it crashes into Jupi te r's swirling atmo Contents sphere. This is an en largement of an image captured by the Hubble Space Tel escope (HSl) on July 1,1993, showing the reg ion of the brig htest nucleus of the comet, torn apart when it came too cl ose to Jupiter in 1992. This "bright nucleus " is actually a group of at least four separate pieces. The span of th is enti re Features image covers abou t 64,000 kilomete rs (40,000 miles). North is at the lower right. Image: H.A. Weaver and Bodies at the 16 Readers' T.E. Smith, Space Te lescope Science Institute, NASA 4 Brink Service Decades ago legendary planetary scientist The new mathematical field of chaos is Gerard P. Kuiper theorized that a band of difficult to penetrate, yet its somewhat comets orbited at the edge of our solar whimsical name and surprising predic From system. Telescopes of his time couldn't tions intrigue even the mathematically test this hypothesis, but now, working unsophisticated. Our featured book looks The with new equipment, astronomers have at chaos' applications to understanding discovered the first evidence that Kuiper our solar system. Editor was right. World Jupiter Watch: 17 Watch es, we have changed the 8 The Celestial Necklace It's a time of birth and death for NASA: Y design of The Planetary Breaks Its program to search for extraterrestrial Report; your eyes do not deceive This July, comet Shoemaker-Levy 9 will radio signals has been canceled by Congress, you. -
Distribution of Chicxulub Ejecta at the Cretaceous-Tertiary Boundary
Geological Society of America Special Paper 356 2002 Distribution of Chicxulub ejecta at the Cretaceous-Tertiary boundary Philippe Claeys* Department of Geology, Vrije Universiteit Brussel, Pleinlann 2, B-1050, Brussels, Belgium Wolfgang Kiessling* Natural History Museum, Invalidenstr. 43 D-10099, Berlin, Germany Walter Alvarez* Department of Earth and Planetary Science, University of California, Berkeley, California 94720-4767, USA ABSTRACT The mineralogical, sedimentological, and geochemical information in a large database on the Cretaceous-Tertiary (K-T) boundary is used to document the distri- bution of impact debris derived from the Chicxulub crater. The database is coupled with a geographic information system (GIS) allowing the plotting of the information on a latest Cretaceous paleogeographic map. The database will be available in part on the internet in the near future, and contains data from 345 K-T boundary sites worldwide. However, relatively few sites are known in South America, Australia, Af- rica, and in the high latitudes. Major disturbances of sedimentation, such as massive debris flows, failure of platform margins, or significant erosion of Upper Cretaceous layers, occur throughout the Gulf of Mexico. Mass wasting of material also took place in the western and eastern parts of the Atlantic Ocean. Almost 100 K-T boundary sites analyzed for Ir recorded the positive anomaly; Ir is spread homogeneously throughout the world, but is diluted at proximal sites because of the high volume of sediment that was in suspension in the Gulf of Mexico after the impact. Shocked quartz is more common, and maybe larger in size west of the crater. The main ad- vantage of the database is to provide a convenient method to manage the huge amount of data available in the literature, and to reveal patterns or characteristics of the data. -
Ice& Stone 2020
Ice & Stone 2020 WEEK 51: DECEMBER 13-19 Presented by The Earthrise Institute # 51 Authored by Alan Hale COMET OF THE WEEK: The Great Comet of 1680 Perihelion: 1680 December 18.49, q = 0.006 AU The Great Comet of 1680 over Rotterdam in The Netherlands, during late December 1680 as painted by the Dutch artist Lieve Verschuier. This particular comet was undoubtedly one of the brightest comets of the 17th Century, but it is also one of the most important comets in history from a scientific perspective, and perhaps even from the perspective of overall human history. While there were certainly plenty of superstitions attached to the comet’s appearance, the scientific investigations made of it were among the beginnings of the era in European history we now call The Enlightenment, and indeed, in a sense the Great Comet of 1680 can perhaps be considered as one of the sparks of that era. The significance began with the comet’s discovery, which was made on the morning of November 14, 1680, by a German astronomer residing in Coburg, Gottfried Kirch – the first comet ever to be discovered by means of a telescope. It was already around 4th magnitude at that time, and located near the star Regulus in the constellation Leo; from that point it traveled eastward and brightened rapidly, being closest to Earth (0.42 AU) on November 30. By that time it was a conspicuous naked-eye object with a tail 20 to 30 degrees long, and it remained visible for another week before disappearing into morning twilight. -
General Assembly Distr.: General 7 January 2005
United Nations A/AC.105/839 General Assembly Distr.: General 7 January 2005 Original: English Committee on the Peaceful Uses of Outer Space Scientific and Technical Subcommittee Forty-second session Vienna, 21 February-4 March 2004 Item 10 of the provisional agenda∗ Near-Earth objects Information on research in the field of near-Earth objects carried out by international organizations and other entities Note by the Secretariat Contents Page I. Introduction ................................................................... 2 II. Replies received from international organizations and other entities ..................... 2 European Space Agency ......................................................... 2 The Spaceguard Foundation ...................................................... 17 __________________ ∗ A/AC.105/C.1/L.277. V.05-80067 (E) 010205 020205 *0580067* A/AC.105/839 I. Introduction In accordance with the agreement reached at the forty-first session of the Scientific and Technical Subcommittee (A/AC.105/823, annex II, para. 18) and endorsed by the Committee on the Peaceful Uses of Outer Space at its forty-seventh session (A/59/20, para. 140), the Secretariat invited international organizations, regional bodies and other entities active in the field of near-Earth object (NEO) research to submit reports on their activities relating to near-Earth object research for consideration by the Subcommittee. The present document contains reports received by 17 December 2004. II. Replies received from international organizations and other entities European Space Agency Overview of activities of the European Space Agency in the field of near-Earth object research: hazard mitigation Summary 1. Near-Earth objects (NEOs) pose a global threat. There exists overwhelming evidence showing that impacts of large objects with dimensions in the order of kilometres (km) have had catastrophic consequences in the past. -
Handbook of Iron Meteorites, Volume 3
1350 Yenberrie - York (Iron) Specimens in the U.S. National Museum in Washington: 3.54 kg on three slices (no. 607) 290 g part slice (no. 1626) York (Iron), Nebraska, U.S.A. Approximately 40°52'N, 97°35'W; 500 m Medium octahedrite, Om. Bandwidth 1.00±0.15 mm. E-structure. HV 305 ±15 . Probably group III A. About 7.7% Ni and 0.12% P. HISTORY A mass of 835 g was found in 1878 on the farm of ~ - . Robert M. Lytle, near York in York County. The mass was Figure 2007. Yenberric (U.S.N.M. no. 607). Taenite with cloudy plowed up from a edges and martensitic interior in which cloudy patches occasionally depth of 20 em in virgin, black loamy occur. Part of the explanation may be sought in the taenite lamella prairie soil. It was in the fmder's possession until 1895 being parallel to the plane of section. Etched. Scale bar 200 J.L. See when it was acquired by Barbour (1898) who described it also Figures 109 and 119. and gave figures of the exterior and of etched slices. COLLECfiONS \ New York (701 g), Washington (30 g). \ ANALYSES Kunz reported (in Barbour 1898) 7.38% Ni and 0 .74% Co. The sum appears correct, but the present author would expect that some of the nickel has been included with the cobalt. The meteorite is estimated to have the following composition: 7 .7±0.2% Ni, 0.50% Co, 0.12±0.02% P, with trace elements placing it in the chemical group IliA. -
Geomagnetic Effect of the Bering Sea Meteoroid
RUSSIAN JOURNAL OF EARTH SCIENCES vol. 20, 6, 2020, doi: 10.2205/2020ES000748 Geomagnetic effect of the Bering Sea meteoroid B. G. Gavrilov1, V. A. Pilipenko2,3, Y. V. Poklad1, I. A. Ryakhovsky1 1Sadovsky Institute of Geosphere Dynamics, Russian Academy of Sciences, (IDG RAS), Moscow, Russia 2Schmidt Institute of Physics of the Earth, Russian Academy of Sciences (IPE RAS), Moscow, Russia 3Geophysical Center RAS (GC RAS), Moscow, Russia c 2020 Geophysical Center RAS Abstract. Possibilities of studies of the geomagnetic effects produced by the interaction of a cosmic bodies with the magnetosphere-ionosphere-atmosphere system are very limited due to extremely small number of examined events. Here we present geomagnetic observations at an array of magnetometers during Bering Sea Bolide event on December 18, 2018 when a space body entered the Earth's atmosphere and exploded at the altitude of ∼ 25 km near Kamchatka. It has been found that the short-lived electromagnetic signal appeared before the explosion and, consequently, was trigged by the passage of a meteoroid through the inner magnetosphere. Geomagnetic disturbances of the same duration and frequency of oscillations were detected both in the area adjacent to the explosion site in the Northern hemisphere and in the magnetically conjugated area in the Southern hemisphere. This is the e-book version of the article, published in Russian Journal of Earth Sciences (doi:10.2205/2020ES000748). It is generated from the original source file using LaTeX's ebook.cls class. These observations may be provisionally inter- preted as a triggered excitation of resonant field line oscillations in the inner magnetosphere by the fast-moving meteoroid. -
Appendix a Recovery of Ejecta Material from Confirmed, Probable
Appendix A Recovery of Ejecta Material from Confirmed, Probable, or Possible Distal Ejecta Layers A.1 Introduction In this appendix we discuss the methods that we have used to recover and study ejecta found in various types of sediment and rock. The processes used to recover ejecta material vary with the degree of lithification. We thus discuss sample processing for unconsolidated, semiconsolidated, and consolidated material separately. The type of sediment or rock is also important as, for example, carbonate sediment or rock is processed differently from siliciclastic sediment or rock. The methods used to take and process samples will also vary according to the objectives of the study and the background of the investigator. We summarize below the methods that we have found useful in our studies of distal impact ejecta layers for those who are just beginning such studies. One of the authors (BPG) was trained as a marine geologist and the other (BMS) as a hard rock geologist. Our approaches to processing and studying impact ejecta differ accordingly. The methods used to recover ejecta from unconsolidated sediments have been successfully employed by BPG for more than 40 years. A.2 Taking and Handling Samples A.2.1 Introduction The size, number, and type of samples will depend on the objective of the study and nature of the sediment/rock, but there a few guidelines that should be followed regardless of the objective or rock type. All outcrops, especially those near industrialized areas or transportation routes (e.g., highways, train tracks) need to be cleaned off (i.e., the surface layer removed) prior to sampling. -
PDF Orientations in Shocked Quartz Grains Around the Chicxulub Crater
Meteoritics & Planetary Science 43, Nr 4, 745–760 (2008) AUTHOR’S PROOF Abstract available online at http://meteoritics.org PDF orientations in shocked quartz grains around the Chicxulub crater Yoichiro NAKANO1, Kazuhisa GOTO2*, Takafumi MATSUI3, Ryuji TADA1, and Eiichi TAJIKA1 1Department of Earth and Planetary Science, Graduate School of Science, The University of Tokyo, Build. #5, 7-3-1 Hongo, Tokyo 113-0033, Japan 2Tsunami Engineering Laboratory, Disaster Control Research Center, Graduate School of Engineering, Tohoku University, Aoba 06-6-11, Aramaki, Sendai 980-8579, Japan 3Department of Complexity Science and Engineering, Graduate School of Frontier Science, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan *Corresponding author. E-mail: [email protected] (Received 07 August 2006; revision accepted 04 September 2007) Abstract–We measured 852 sets of planar deformation features (PDFs) in shocked quartz grains in impactite samples of the Yaxcopoil (YAX-1) core and from 4 Cretaceous/Tertiary (K/T) boundary deposits: the Monaca, the Cacarajícara, and the Peñalver formations in Cuba, and DSDP site 536, within 800 km of the Chicxulub crater, in order to investigate variations of PDF orientations in_ the ω proximity_ of the crater._ Orientations of_ PDFs show a broad distribution with peaks_ at _{1013}, π ξ {10_12}, and {1112},_ plus r, z {101_ 1} orientations with minor c(0001), s{1121}, t{2241} plus x{5161}, and m{1010} plus a{1120} orientations. Planar deformation features with c(0001) orientation are relatively more abundant in the proximity of the Chicxulub crater than in distal sites such as North America, the Pacific Ocean, and Europe. -
Michael W. Busch Updated June 27, 2019 Contact Information
Curriculum Vitae: Michael W. Busch Updated June 27, 2019 Contact Information Email: [email protected] Telephone: 1-612-269-9998 Mailing Address: SETI Institute 189 Bernardo Ave, Suite 200 Mountain View, CA 94043 USA Academic & Employment History BS Physics & Astrophysics, University of Minnesota, awarded May 2005. PhD Planetary Science, Caltech, defended April 5, 2010. JPL Planetary Science Summer School, July 2006. Hertz Foundation Graduate Fellow, September 2007 to June 2010. Postdoctoral Researcher, University of California Los Angeles, August 2010 – August 2011. Jansky Fellow, National Radio Astronomy Observatory, August 2011 – August 2014. Visiting Scholar, University of Colorado Boulder, July – August 2012. Research Scientist, SETI Institute, August 2013 – present. Current Funding Sources: NASA Near Earth Object Observations. Research Interests: • Shapes, spin states, trajectories, internal structures, and histories of asteroids. • Identifying and characterizing targets for both robotic and human spacecraft missions. • Ruling out potential future asteroid-Earth impacts. • Radio and radar astronomy techniques. Selected Recent Papers: Marshall, S.E., and 24 colleagues, including Busch, M.W., 2019. Shape modeling of potentially hazardous asteroid (85989) 1999 JD6 from radar and lightcurve data, Icarus submitted. Reddy, V., and 69 colleagues, including Busch, M.W., 2019. Near-Earth asteroid 2012 TC4 campaign: results from global planetary defense exercise, Icarus 326, 133-150. Brozović, M., and 16 colleagues, including Busch, M.W., 2018. Goldstone and Arecibo radar observations of (99942) Apophis in 2012-2013, Icarus 300, 115-128. Brozović, M., and 19 colleagues, including Busch, M.W., 2017. Goldstone radar evidence for short-axis mode non-principal axis rotation of near-Earth asteroid (214869) 2007 PA8. Icarus 286, 314-329.