DOCSLIB.ORG

Asteroid Science

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Asteroid Science Deutsches Zentrum für Luft- und Raumfahrt e.V. German Aerospace Center Institut für Planetenforschung Institute of Planetary Research DEPARTMENT: “ASTEROIDS AND COMETS” IX. Annual Report 2005 Comets ASTEROIDS MODELS SPACE MISSIONS http://solarsystem.dlr.de/KK From left to right Dr. Jörg Knollenberg [email protected] Scientific staff member Dr. Gerhard Hahn [email protected] Scientific staff member Dr. Ekkehard Kührt [email protected] Section leader Prof. Uwe Motschmann [email protected] Guest scientist Laura Brumm [email protected] Secretary Detlef de Niem [email protected] Scientific staff member Dr. Carmen Tornow [email protected] Scientific staff member Michael Müller [email protected] PhD student Dr. Alan W. Harris [email protected] Deputy section leader Not appearing in the photo: Dr. Stefano Mottola [email protected] Scientific staff member Thermal-infrared image (8 – 14 μm), changed order 2 Contents 1. Introduction (EK) 2. Asteroid science 2.1 Investigations of the physical properties of asteroids with the NASA Infrared Telescope Facility (Harris, Müller) 2.2 Observations of asteroids with the Spitzer Space Telescope (Harris, Mueller) 2.3 Asteroid thermal modelling (Müller, Harris) 2.4 Photometric observations of main-belt and near-Earth asteroids (Mottola, Hahn, Harris, Müller) 2.5 Asteroid search and follow-up programmes (Hahn) 2.6 Orbital evolution studies of Saturn family comets (Hahn) 3. Comet science 3.1 Hydrodynamical influence on formation of HCN molecules in hot cores (Tornow, Kührt, Motschmann) 3.2 Modelling the solar wind interaction with weakly outgassing comets by a hybrid model (Motschmann, Kührt) 4. Impact phenomena 4.1 Meteorite ejecta range after terrestrial impacts (de Niem, Kührt, Motschmann) 4.2. Physical limits of solar collectors in deflecting Earth-threatening asteroids (Kahle, Kührt, Hahn, Knollenberg) 5. Contributions to space missions 5.1 Rosetta-Mupus (Knollenberg, Kührt, Spohn, Schrödter) 5.2 Rosetta-Rolis (S. Mottola, H. Michaelis) 5.3 DAWN (S. Mottola, R. Jaumann) 5.4 Don Quijote: Study of a hazardous asteroid mitigation pre-cursor mission (Harris) 5.5 Deep Impact measurements and simulations (Knollenberg, de Niem, Kührt) 6. Technology projects 6.1 HP3 (Knollenberg, Nadalini) 6.2 FIREWATCH (Kührt, Knollenberg, Behnke, Mertens) 7. Appendix 7.1 Scientific publications in refereed journals and books (submitted or published in 2004) 7.2 Scientific publications in other journals and proceedings (published in 2004) 7.3. Minor Planet Circulars/Electronic Circulars 7.4 Publications in the popular literature and public outreach 7.5 Observing campaigns 2004 7.6 Space mission responsibilities 7.7 Other events and activities 7.8 Funding 3 1. Introduction (E. Kührt) This report describes the work of the “Asteroids and Comets” Department of the Institute of Planetary Research of the DLR (German Aerospace Center) during the year 2005. The Department consisted of 7 scientists and 1 PhD student; two guest scientists, one from the Assam University, India, and one from the Technical University Braunschweig, worked in the Department during the year. Our scientific goal is to investigate small bodies by observing them in the visible, infrared, and other wavelength ranges, contributing to relevant space missions and modelling physical processes associated with this class of object. Other fields of interest are risk evaluation of impacts of Near Earth Objects (NEOs) on our home planet, the origin of life and the transfer of space technology to solve environmental problems on Earth. Scientific interest in the minor bodies of the Solar System stems mainly from the crucial role they appear to have played in the formation of the planets and the development of life. Asteroids and comets are thought to be remnant material from the process of formation and the initial development of planets. Due to their peculiar dynamical and physical properties, such as small size, lack of a permanent atmosphere, and relatively little thermal processing, these objects have remained largely unaltered since the time of Solar System formation. Consequently, comets and asteroids should contain a wealth of information on conditions in the protoplanetary nebula. Many scientists believe that comets and asteroids have significantly influenced the evolution of the terrestrial planets and life on Earth. In particular, scientific and public interest in near-Earth asteroids has risen in recent years. Activities in these fields are a part of our DLR-project “Comets and asteroids”. They are summarized in Sections 2, 3, and 4. Contributions to several space missions are described in Section 5. We are involved in Rosetta to comet Churyumov-Gerasimenko with 1 Principal Investigator, 1 Project Manager and 8 Coinvestgator-ships and in the Science Team of the DAWN mission to asteroids Ceres and Vesta. The progress in our technology transfer projects is discussed in Section 6. The Appendix summarises publications, project contributions, observation campaigns, public outreach activities, and our funding. 2. Asteroid Science 2.1. Investigations of the physical properties of asteroids with the NASA Infrared Telescope Facility (Harris, Müller) The NASA Infrared Telescope Facility (IRTF) is a 3-m telescope situated on Mauna Kea, Hawaii. Our project has been awarded observing time on the IRTF regularly over the past 5 years. It has recently become possible to carry out observations remotely from Berlin, which means that, without heavy travel costs, observing time can be scheduled at intervals of a few days over a total period of weeks to study the variation of infrared emission from asteroids as their observing geometry changes. The resulting data can reveal important information on the surface characteristics of asteroids, especially thermal inertia. A major focus of our work with the IRTF is near-Earth asteroids (NEAs). This year saw the publication in Icarus of our work on (1580) Betulia, in which revised values of size and albedo and a thermal inertia of 180 J m-2s-0.5 K-1 were obtained for this unusual C- type NEA. This is amongst the first determinations of thermal inertia for NEAs; it is some three times higher than the lunar value but an order of magnitude less than that expected for a bare rock surface. Our result for Betulia is consistent with recently obtained values for other NEAs discussed in Section 2.3. Our programme was awarded a total of 8 x 0.5 nights of observing time with the NASA IRTF in the 2005 observing schedule. However, the quality of thermal-infrared data, especially in the case of weak targets, is very dependent on atmospheric conditions and on several occasions in 2005 we were forced to turn to a back-up programme of observations of relatively bright main-belt M-type asteroids because of unfavourable conditions. 4 Fig. 2.1 Thermal-infrared flux measurements of the M-type asteroid (16) Psyche, Higher thermal inertia with model thermal continua for different values of thermal inertia overlaid. The flux measurements in the case of Psyche are Very low thermal inertia indicative of relatively high thermal inertia. The data set shown was taken in 2004. Similar data sets were obtained in 2005 for all the M-type asteroids mentioned in the text. One of the major current questions concerning asteroid mineralogy is the nature of M-type asteroids. Are M-type asteroids really metallic or not? We were able to obtain useful multi-filter thermal-infrared flux measurements of the main-belt M-type asteroids (16) Psyche, (21) Lutetia, (129) Antigone, (135) Hertha, (201) Penelope, (216) Kleopatra, and (785) Zwetana. Preliminary results indicate that (16) Psyche and (216) Kleopatra have relatively high values of thermal inertia. Furthermore, Psyche and Kleopatra also have very high radar albedos and therefore presumably have metallic surfaces. On the other hand, Lutetia appears to have normal values of thermal inertia and radar reflectivity. In the cases of Lutetia, Antigone, Hertha, and Penelope, for which our observations indicate normal thermal inertia, near-infrared reflectance spectroscopy provides evidence for hydrated surfaces, indicating that these objects are not metallic. To summarize: there may be a correlation between thermal inertia and radar reflectivity, which would indicate that thermal inertia is a useful indicator of metallic surfaces, and our results are consistent with recent findings that many M-type asteroids appear to be of non-metallic composition. Our study of the physical characteristics of (21) Lutetia was completed with the acceptance of the work for publication in Astronomy and Astrophysics. Our derived albedo of 0.21, typical for an M- type object, agrees well with the IRAS albedo and rules out the possibility, suggested on the basis of spectroscopic observations, that Lutetia may actually have a carbonaceous composition. 2.2. Observations of asteroids with the Spitzer Space Telescope (Harris, Mueller) Two proposals submitted for observing time with Spitzer (Figure 2.2) in 2005 were awarded a total of 24 hr. observing time. The programmes are led by Harris and Mueller, respectively, and include a total of 7 co-investigators from Europe and the USA: 1. The Karin cluster asteroids in the main belt display very similar proper orbital elements and are therefore assumed to be dynamically related. The cluster, named after its largest member, (832) Karin, is believed to have been formed 5.8 ± 0.2 Myr ago in a catastrophic collision and thus to be significantly younger than most known asteroid families. The cluster is of great interest due to the fact that the physical properties of its members may preserve unique information about asteroid fragmentation and surface processes on small asteroids, which include regolith formation and modification of albedo and spectral properties via space weathering. Our Spitzer observations of 17 Karin cluster members should allow us to determine their sizes, albedos and information on thermal inertia. The questions that can be addressed with these observations include: Are the distributions of sizes and albedos compatible with the Karin cluster being the result of a single catastrophic collision Fig.
Load more

Recommended publications
  • Asteroid Shape and Spin Statistics from Convex Models J
    Asteroid shape and spin statistics from convex models J. Torppa, V.-P. Hentunen, P. Pääkkönen, P. Kehusmaa, K. Muinonen To cite this version: J. Torppa, V.-P. Hentunen, P. Pääkkönen, P. Kehusmaa, K. Muinonen. Asteroid shape and spin statistics from convex models. Icarus, Elsevier, 2008, 198 (1), pp.91. 10.1016/j.icarus.2008.07.014. hal-00499092 HAL Id: hal-00499092 https://hal.archives-ouvertes.fr/hal-00499092 Submitted on 9 Jul 2010 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Accepted Manuscript Asteroid shape and spin statistics from convex models J. Torppa, V.-P. Hentunen, P. Pääkkönen, P. Kehusmaa, K. Muinonen PII: S0019-1035(08)00283-2 DOI: 10.1016/j.icarus.2008.07.014 Reference: YICAR 8734 To appear in: Icarus Received date: 18 September 2007 Revised date: 3 July 2008 Accepted date: 7 July 2008 Please cite this article as: J. Torppa, V.-P. Hentunen, P. Pääkkönen, P. Kehusmaa, K. Muinonen, Asteroid shape and spin statistics from convex models, Icarus (2008), doi: 10.1016/j.icarus.2008.07.014 This is a PDF file of an unedited manuscript that has been accepted for publication.
    [Show full text]
  • Space Situational Awareness
    → SPACE SITUATIONAL AWARENESS OUTLINE - Background - Purpose - Aims - Composition - Space Surveillance (SST) - Space Weather (SWE) - Near-Earth Objects (NEO) - Summary 2 BACKGROUND Image: Dan Durda – FIAAA 3 INTRODUCTION PURPOSE OF THE SSA PROGRAMME “The objective of the Space Situational Awareness (SSA) programme is to support the European independent utilisation of, and access to, space for research or services, through the provision of timely and quality data, information, services and knowledge regarding the space environment, the threats and the sustainable exploitation of the outer space surrounding our planet Earth.” - ESA Ministerial Council November 2008 4 INTRODUCTION AIMS OF THE SSA PROGRAMME • Independent utilisation of Space – Space assets are critical assets • Guarantee access to Space – Diplomatic, – Political – Regulatory – Technical • Serve EU “Lisbon Objectives” – New Applications – New Jobs – New Markets 5 INTRODUCTION CUSTOMERS FOR SSA SERVICES • European Governments • Space Insurance • United Nations – EU • Space Industry • Defence – National • Energy • Civil Protection – Regional – Surveying • European Space Agencies – Electrical Grid – ESA – Power Supply – National • Network Operations • Spacecraft Operators • Telecommunications – Commercial • Air Traffic Control – Academic • Search and Rescue Entities – Governmental 6 INTRODUCTION Current Objectives 2009 – 2012 • Preparatory Programme – Governance Definition – Data Policy – Architecture – Federation – Precursor Services – Radar Breadboard – Pilot Data Centres 2012
    [Show full text]
  • Radar Imaging of Asteroid 7 Iris
    Icarus 207 (2010) 285–294 Contents lists available at ScienceDirect Icarus journal homepage: www.elsevier.com/locate/icarus Radar imaging of Asteroid 7 Iris S.J. Ostro a,1, C. Magri b,*, L.A.M. Benner a, J.D. Giorgini a, M.C. Nolan c, A.A. Hine c, M.W. Busch d, J.L. Margot e a Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA b University of Maine at Farmington, 173 High Street – Preble Hall, Farmington, ME 04938, USA c Arecibo Observatory, HC3 Box 53995, Arecibo, PR 00612, USA d Division of Geological and Planetary Sciences, California Institute of Technology, MC 150-21, Pasadena, CA 91125, USA e Department of Earth and Space Sciences, University of California, Los Angeles, 595 Charles Young Drive East, Box 951567, Los Angeles, CA 90095, USA article info abstract Article history: Arecibo radar images of Iris obtained in November 2006 reveal a topographically complex object whose Received 26 June 2009 gross shape is approximately ellipsoidal with equatorial dimensions within 15% of 253 Â 228 km. The Revised 10 October 2009 radar view of Iris was restricted to high southern latitudes, precluding reliable estimation of Iris’ entire Accepted 7 November 2009 3D shape, but permitting accurate reconstruction of southern hemisphere topography. The most promi- Available online 24 November 2009 nent features, three roughly 50-km-diameter concavities almost equally spaced in longitude around the south pole, are probably impact craters. In terms of shape regularity and fractional relief, Iris represents a Keywords: plausible transition between 50-km-diameter asteroids with extremely irregular overall shapes and Asteroids very large concavities, and very much larger asteroids (Ceres and Vesta) with very regular, nearly convex Radar observations shapes and generally lacking monumental concavities.
    [Show full text]
  • Avant Première Catalogue 2018 Lists UNITEL’S New Productions of 2017 Plus New Additions to the Catalogue
    CATALOGUE 2018 This Avant Première catalogue 2018 lists UNITEL’s new productions of 2017 plus new additions to the catalogue. For a complete list of more than 2.000 UNITEL productions and the Avant Première catalogues of 2015–2017 please visit www.unitel.de FOR CO-PRODUCTION & PRESALES INQUIRIES PLEASE CONTACT: Unitel GmbH & Co. KG Gruenwalder Weg 28D · 82041 Oberhaching/Munich, Germany Tel: +49.89.673469-613 · Fax: +49.89.673469-610 · [email protected] Ernst Buchrucker Dr. Thomas Hieber Dr. Magdalena Herbst Managing Director Head of Business and Legal Affairs Head of Production [email protected] [email protected] [email protected] Tel: +49.89.673469-19 Tel: +49.89.673469-611 Tel: +49.89.673469-862 WORLD SALES C Major Entertainment GmbH Meerscheidtstr. 8 · 14057 Berlin, Germany Tel.: +49.30.303064-64 · [email protected] Elmar Kruse Niklas Arens Nishrin Schacherbauer Managing Director Sales Manager, Director Sales Sales Manager [email protected] & Marketing [email protected] [email protected] Nadja Joost Ira Rost Sales Manager, Director Live Events Sales Manager, Assistant to & Popular Music Managing Director [email protected] [email protected] CATALOGUE 2018 Unitel GmbH & Co. KG Gruenwalder Weg 28D 82041 Oberhaching/Munich, Germany CEO: Jan Mojto Editorial team: Franziska Pascher, Dr. Martina Kliem, Arthur Intelmann Layout: Manuel Messner/luebbeke.com All information is not contractual and subject to change without prior notice. All trademarks used herein are the property of their respective owners. Date of Print: February 2018 © UNITEL 2018 All rights reserved Front cover: Alicia Amatriain & Friedemann Vogel in John Cranko’s “Onegin” / Photo: Stuttgart Ballet ON THE OCCASION OF HIS 100TH BIRTHDAY UNITEL CELEBRATES LEONARD BERNSTEIN 1918 – 1990 Leonard Bernstein, a long-time exclusive artist of Unitel, was America’s ambassador to the world of music.
    [Show full text]
  • The Minor Planet Bulletin
    THE MINOR PLANET BULLETIN OF THE MINOR PLANETS SECTION OF THE BULLETIN ASSOCIATION OF LUNAR AND PLANETARY OBSERVERS VOLUME 36, NUMBER 3, A.D. 2009 JULY-SEPTEMBER 77. PHOTOMETRIC MEASUREMENTS OF 343 OSTARA Our data can be obtained from http://www.uwec.edu/physics/ AND OTHER ASTEROIDS AT HOBBS OBSERVATORY asteroid/. Lyle Ford, George Stecher, Kayla Lorenzen, and Cole Cook Acknowledgements Department of Physics and Astronomy University of Wisconsin-Eau Claire We thank the Theodore Dunham Fund for Astrophysics, the Eau Claire, WI 54702-4004 National Science Foundation (award number 0519006), the [email protected] University of Wisconsin-Eau Claire Office of Research and Sponsored Programs, and the University of Wisconsin-Eau Claire (Received: 2009 Feb 11) Blugold Fellow and McNair programs for financial support. References We observed 343 Ostara on 2008 October 4 and obtained R and V standard magnitudes. The period was Binzel, R.P. (1987). “A Photoelectric Survey of 130 Asteroids”, found to be significantly greater than the previously Icarus 72, 135-208. reported value of 6.42 hours. Measurements of 2660 Wasserman and (17010) 1999 CQ72 made on 2008 Stecher, G.J., Ford, L.A., and Elbert, J.D. (1999). “Equipping a March 25 are also reported. 0.6 Meter Alt-Azimuth Telescope for Photometry”, IAPPP Comm, 76, 68-74. We made R band and V band photometric measurements of 343 Warner, B.D. (2006). A Practical Guide to Lightcurve Photometry Ostara on 2008 October 4 using the 0.6 m “Air Force” Telescope and Analysis. Springer, New York, NY. located at Hobbs Observatory (MPC code 750) near Fall Creek, Wisconsin.
    [Show full text]
  • Welcome Guide for Researchers Getting Started in Dresden‘S Research Landscape
    WELCOME GUIDE FOR RESEARCHERS Getting started in Dresden‘s research landscape 1 INDEX Rector´s statement..................................................................................4 Before arrival Visa and entry..........................................................................................5 Travel health insurance and important documents..............................6 Family After arrival Dual Career Service ...................................................................30 Local registration .....................................................................................8 Childcare.................................................................................... 31 Residence and work permit .......................................................................9 School system........................................................................... 33 Funding...........................................................................................................10 School registration..................................................................... 34 Social security system.............................................................................12 Benefits for families...................................................................35 Health insurance.....................................................................................13 Having a baby............................................................................. 37 General information on housing................................................................14
    [Show full text]
  • CATALOGUE 2018 This Avant Première Catalogue 2018 Lists UNITEL’S New Productions of 2017 CATALOGUE 2018 Plus New Additions to the Catalogue
    CATALOGUE 2018 This Avant Première catalogue 2018 lists UNITEL’s new productions of 2017 CATALOGUE 2018 plus new additions to the catalogue. For a complete list of more than 2.000 UNITEL productions and the Avant Première catalogues of 2015–2017 please visit www.unitel.de FOR CO-PRODUCTION & PRESALES INQUIRIES PLEASE CONTACT: Unitel GmbH & Co. KG Gruenwalder Weg 28D · 82041 Oberhaching/Munich, Germany Tel: +49.89.673469-613 · Fax: +49.89.673469-610 · [email protected] Ernst Buchrucker Dr. Thomas Hieber Dr. Magdalena Herbst Managing Director Head of Business and Legal Affairs Head of Production [email protected] [email protected] [email protected] Tel: +49.89.673469-19 Tel: +49.89.673469-611 Tel: +49.89.673469-862 Unitel GmbH & Co. KG Gruenwalder Weg 28D 82041 Oberhaching/Munich, Germany WORLD SALES CEO: Jan Mojto C Major Entertainment GmbH Meerscheidtstr. 8 · 14057 Berlin, Germany Tel.: +49.30.303064-64 · [email protected] Editorial team: Franziska Pascher, Dr. Martina Kliem, Arthur Intelmann Layout: Manuel Messner/luebbeke.com Elmar Kruse Niklas Arens Nishrin Schacherbauer Managing Director Sales Manager, Director Sales Sales Manager All information is not contractual and subject to change without prior notice. [email protected] & Marketing [email protected] All trademarks used herein are the property of their respective owners. [email protected] Date of Print: February 2018 © UNITEL 2018 All rights reserved Nadja Joost Ira Rost Sales Manager, Director Live Events Sales Manager, Assistant to & Popular Music Managing Director Front cover: Alicia Amatriain & Friedemann Vogel in John Cranko’s “Onegin” / Photo: Stuttgart Ballet [email protected] [email protected] ON THE OCCASION OF HIS 100TH BIRTHDAY UNITEL CELEBRATES AVAILABLE FOR THE FIRST TIME FOR GLOBAL DISTRIBUTION LEONARD BERNSTEIN 1918 – 1990 Leonard Bernstein, a long-time exclusive artist of Unitel, was America’s ambassador to the world of music.
    [Show full text]
  • The Hera Mission
    Dr. Patrick Michel Hera Investigation Team PI Université Côte d’Azur Observatoire de la Côte d’Azur CNRS, Lagrange Laboratory Nice, France The Hera Mission ESA UNCLASSIFIED - For Official Use Hera main aspects Role of space missions at ESA in NEO hazard mitigation • Understanding the problem (deflection modeling and simulations) 2001 • Ground versus space solutions analyses • Assessment of space component options 2002- • 6 parallel phase-0 studies (3 space telescopes, 3 rendezvous) Euneos Nero Earthguard 1 2004 • ESA’s NEO Mission Advisory Panel (NEOMAP) established • Kinetic impactor validation ranked highest importance 2004- • Don Quijote mission selected and studied up to phase-A level 2006 • SANCHO / Proba-IP orbiter up to phase A level studies, small deep-space Don Quijote Ishtar Simone 2008- mission to investigate impactor’s result 2009 • AIDA proposed by NASA: USA/impactor + ESA/impact assessment • ESA phase 0 and phase A studies on the observer spacecraft "AIM” (GSP) 2011- Proba-IP 2016 • Phase B1 study and “consolidation phase” for mission definition (GSTP) • HERA: impact observer spacecraft reformulation and optimization AIM 2017- • Phase B1 implementation + payload + technology breadboards (GSTP+SSA) Several concepts 2019 • DART phase-C kick-off on 15 May 2018 Hera iterated AIDA: An International Planetary Defense Mission U.S. National Research Council Committee “Defending Planet Earth: Near-Earth Object Surveys and Hazard Mitigation Strategies” Recommendation: “If [U.S.] Congress chooses to fund mitigation research at an appropriately high level, the first priority for a space mission in the mitigation area is an experimental test of a kinetic impactor along with a characterization, monitoring, and verification system, such as the Don Quixote mission that was previously considered, but not funded, by the European Space Agency.
    [Show full text]
  • Asteroid Retrieval Feasibility Study
    Asteroid Retrieval Feasibility Study 2 April 2012 Prepared for the: Keck Institute for Space Studies California Institute of Technology Jet Propulsion Laboratory Pasadena, California 1 2 Authors and Study Participants NAME Organization E-Mail Signature John Brophy Co-Leader / NASA JPL / Caltech [email protected] Fred Culick Co-Leader / Caltech [email protected] Co -Leader / The Planetary Louis Friedman [email protected] Society Carlton Allen NASA JSC [email protected] David Baughman Naval Postgraduate School [email protected] NASA ARC/Carnegie Mellon Julie Bellerose [email protected] University Bruce Betts The Planetary Society [email protected] Mike Brown Caltech [email protected] Michael Busch UCLA [email protected] John Casani NASA JPL [email protected] Marcello Coradini ESA [email protected] John Dankanich NASA GRC [email protected] Paul Dimotakis Caltech [email protected] Harvard -Smithsonian Center for Martin Elvis [email protected] Astrophysics Ian Garrick-Bethel UCSC [email protected] Bob Gershman NASA JPL [email protected] Florida Institute for Human and Tom Jones [email protected] Machine Cognition Damon Landau NASA JPL [email protected] Chris Lewicki Arkyd Astronautics [email protected] John Lewis University of Arizona [email protected] Pedro Llanos USC [email protected] Mark Lupisella NASA GSFC [email protected] Dan Mazanek NASA LaRC [email protected] Prakhar Mehrotra Caltech [email protected]
    [Show full text]
  • To Thermal History of Metallic Asteroids
    44th Lunar and Planetary Science Conference (2013) 1129.pdf TO THERMAL HISTORY OF METALLIC ASTEROIDS. E.N. Slyuta, Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, 119991, Kosygin St. 19, Moscow, Russia. [email protected]. Introduction: Physical-mechanical properties of interval of temperatures T-transition from plastic to a iron meteorites depend on structure, chemical and min- fragile condition in iron meteorites is not observed that eralogical composition, from short-term shock loading usually is not characteristic for technical alloys and and from temperature [1]. The yield strength increases, steels at which at decreasing of temperature the plas- if size of kamacite and rhabdites crystals decreases, ticity can decrease down to 0. For example, for iron- and nickel and carbon contents increases. The more Ni nickel alloy at Ni content about 5% the curve T-bend is content, the more taenite, microhardness of which is observed already about 200 K [5]. The mechanism of more than one of kamacite, and accordingly more yield plastic deformation in iron meteorites at low tempera- strength. Short-term shock loading up to 25 GPа also tures varies only. Deformation at 300 K occurs by slid- increases the yield strength. The temperature of small ing, and at 4.2 K and 77 K is accompanied by forma- bodies which unlike planetary bodies have no en- tion and development of static twins, i.e. mechanical dogenic activity and an internal thermal flux, is de- twinning as the basic mechanism of deformation in fined by insolation level and depends on a body posi- iron meteorites at low temperatures dominates [6].
    [Show full text]
  • Asteroids, Comets, Meteors 1991, Pp. 641-643 Lunar and Planetary Institute, Houston, 1992 W/Eg- 641
    Asteroids, Comets, Meteors 1991, pp. 641-643 Lunar and Planetary Institute, Houston, 1992 w/eg- 641 THE MASS OF (1) CERES FROM PERTURBATIONS ON (348) MAY Gareth V. Williams Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, U.S.A. ABSTRACT The most promising ground-based technique for determining the mass of s minor planet is the observation of the perturbations it induces in the motion of another minor planet. This method requires cv.reful observation of both minor planets over extended periods of time. The mass of (1) Ceres has been determined from the perturbations on (348) May, which made three close approaches to Ceres at intervals of 46 years between 1891 and 1984. The motion of May is clearly influenced by Ceres, and by Using different test masses for Ceres, a search has been made to determine the mass of Ceres that minimizes the residuals in the observations of May. Introduction The masses of the largest minor planets are rather poorly known. Traditionally, the masses of the major planets were obtained by observing their mutual perturbations or by observing their satellite systems. These methods are not easily applicable to minor planets: no minor planets are known to have satellites; the minor-planet perturbations on any of the major planets are negligible (from a ground-based viewpoint, except by tracking spacecraft); and the mutual minor-planet perturbations generally are small. However, the mutual-perturbation method, when applied to suitable objects, is the best ground-based method currently available for determimng minor-planet masses. The best circumstances for using this method occur when one of the minor planets is large compared to the other, when the two objects make close, periodic approaches to each other, and when both have long observational histories.
    [Show full text]
  • 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.
    [Show full text]