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Avdellidou C, Delbo' M, Nesvorný D, Walsh KJ, Morbidelli A. Dating the Solar System's giant planet orbital instability using enstatite meteorites. Science 2024; 384:348-352. [PMID: 38624242 DOI: 10.1126/science.adg8092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 02/16/2024] [Indexed: 04/17/2024]
Abstract
The giant planets of the Solar System formed on initially compact orbits, which transitioned to the current wider configuration by means of an orbital instability. The timing of that instability is poorly constrained. In this work, we use dynamical simulations to demonstrate that the instability implanted planetesimal fragments from the terrestrial planet region into the asteroid main belt. We use meteorite data to show that the implantation occurred >60 million years (Myr) after the Solar System began to form. Combining this constraint with a previous upper limit derived from Jupiter's trojan asteroids, we conclude that the orbital instability occurred 60 to 100 Myr after the beginning of Solar System formation. The giant impact that formed the Moon occurred within this range, so it might be related to the giant planet instability.
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Affiliation(s)
- Chrysa Avdellidou
- Laboratoire Lagrange, Centre National de la Recherche Scientifique, Observatoire de la Côte d'Azur, Université Côte d'Azur, 06304 Nice, France
- School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
| | - Marco Delbo'
- Laboratoire Lagrange, Centre National de la Recherche Scientifique, Observatoire de la Côte d'Azur, Université Côte d'Azur, 06304 Nice, France
- School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
| | | | - Kevin J Walsh
- Southwest Research Institute, Boulder, CO 80302, USA
| | - Alessandro Morbidelli
- Laboratoire Lagrange, Centre National de la Recherche Scientifique, Observatoire de la Côte d'Azur, Université Côte d'Azur, 06304 Nice, France
- Collège de France, Centre National de la Recherche Scientifique, Université Paris Sciences et Lettres, Sorbonne Université, 75014 Paris, France
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2
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Manrique PD, Huo FY, El Oud S, Zheng M, Illari L, Johnson NF. Shockwavelike Behavior across Social Media. PHYSICAL REVIEW LETTERS 2023; 130:237401. [PMID: 37354390 DOI: 10.1103/physrevlett.130.237401] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 01/30/2023] [Accepted: 03/28/2023] [Indexed: 06/26/2023]
Abstract
Online communities featuring "anti-X" hate and extremism, somehow thrive online despite moderator pressure. We present a first-principles theory of their dynamics, which accounts for the fact that the online population comprises diverse individuals and evolves in time. The resulting equation represents a novel generalization of nonlinear fluid physics and explains the observed behavior across scales. Its shockwavelike solutions explain how, why, and when such activity rises from "out-of-nowhere," and show how it can be delayed, reshaped, and even prevented by adjusting the online collective chemistry. This theory and findings should also be applicable to anti-X activity in next-generation ecosystems featuring blockchain platforms and Metaverses.
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Affiliation(s)
- Pedro D Manrique
- Physics Department, George Washington University, Washington, DC 20052, USA
| | - Frank Yingjie Huo
- Physics Department, George Washington University, Washington, DC 20052, USA
| | - Sara El Oud
- Physics Department, George Washington University, Washington, DC 20052, USA
| | - Minzhang Zheng
- Physics Department, George Washington University, Washington, DC 20052, USA
| | - Lucia Illari
- Physics Department, George Washington University, Washington, DC 20052, USA
| | - Neil F Johnson
- Physics Department, George Washington University, Washington, DC 20052, USA
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3
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NAKAMURA E, KOBAYASHI K, TANAKA R, KUNIHIRO T, KITAGAWA H, POTISZIL C, OTA T, SAKAGUCHI C, YAMANAKA M, RATNAYAKE DM, TRIPATHI H, KUMAR R, AVRAMESCU ML, TSUCHIDA H, YACHI Y, MIURA H, ABE M, FUKAI R, FURUYA S, HATAKEDA K, HAYASHI T, HITOMI Y, KUMAGAI K, MIYAZAKI A, NAKATO A, NISHIMURA M, OKADA T, SOEJIMA H, SUGITA S, SUZUKI A, USUI T, YADA T, YAMAMOTO D, YOGATA K, YOSHITAKE M, ARAKAWA M, FUJII A, HAYAKAWA M, HIRATA N, HIRATA N, HONDA R, HONDA C, HOSODA S, IIJIMA YI, IKEDA H, ISHIGURO M, ISHIHARA Y, IWATA T, KAWAHARA K, KIKUCHI S, KITAZATO K, MATSUMOTO K, MATSUOKA M, MICHIKAMI T, MIMASU Y, MIURA A, MOROTA T, NAKAZAWA S, NAMIKI N, NODA H, NOGUCHI R, OGAWA N, OGAWA K, OKAMOTO C, ONO G, OZAKI M, SAIKI T, SAKATANI N, SAWADA H, SENSHU H, SHIMAKI Y, SHIRAI K, TAKEI Y, TAKEUCHI H, TANAKA S, TATSUMI E, TERUI F, TSUKIZAKI R, WADA K, YAMADA M, YAMADA T, YAMAMOTO Y, YANO H, YOKOTA Y, YOSHIHARA K, YOSHIKAWA M, YOSHIKAWA K, FUJIMOTO M, WATANABE SI, TSUDA Y. On the origin and evolution of the asteroid Ryugu: A comprehensive geochemical perspective. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2022; 98:227-282. [PMID: 35691845 PMCID: PMC9246647 DOI: 10.2183/pjab.98.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 05/06/2022] [Indexed: 05/28/2023]
Abstract
Presented here are the observations and interpretations from a comprehensive analysis of 16 representative particles returned from the C-type asteroid Ryugu by the Hayabusa2 mission. On average Ryugu particles consist of 50% phyllosilicate matrix, 41% porosity and 9% minor phases, including organic matter. The abundances of 70 elements from the particles are in close agreement with those of CI chondrites. Bulk Ryugu particles show higher δ18O, Δ17O, and ε54Cr values than CI chondrites. As such, Ryugu sampled the most primitive and least-thermally processed protosolar nebula reservoirs. Such a finding is consistent with multi-scale H-C-N isotopic compositions that are compatible with an origin for Ryugu organic matter within both the protosolar nebula and the interstellar medium. The analytical data obtained here, suggests that complex soluble organic matter formed during aqueous alteration on the Ryugu progenitor planetesimal (several 10's of km), <2.6 Myr after CAI formation. Subsequently, the Ryugu progenitor planetesimal was fragmented and evolved into the current asteroid Ryugu through sublimation.
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Affiliation(s)
- Eizo NAKAMURA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Katsura KOBAYASHI
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Ryoji TANAKA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Tak KUNIHIRO
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Hiroshi KITAGAWA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Christian POTISZIL
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Tsutomu OTA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Chie SAKAGUCHI
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Masahiro YAMANAKA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Dilan M. RATNAYAKE
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Havishk TRIPATHI
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Rahul KUMAR
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Maya-Liliana AVRAMESCU
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Hidehisa TSUCHIDA
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Yusuke YACHI
- The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry, Institute for Planetary Materials, Okayama University, Misasa, Tottori, Japan
| | - Hitoshi MIURA
- Department of Information and Basic Science, Nagoya City University, Nagoya, Aichi, Japan
| | - Masanao ABE
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Ryota FUKAI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Shizuho FURUYA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Kentaro HATAKEDA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Tasuku HAYASHI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Yuya HITOMI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Marine Works Japan, Ltd., Yokosuka, Kanagawa, Japan
| | - Kazuya KUMAGAI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Marine Works Japan, Ltd., Yokosuka, Kanagawa, Japan
| | - Akiko MIYAZAKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Aiko NAKATO
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Masahiro NISHIMURA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Tatsuaki OKADA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
| | - Hiromichi SOEJIMA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Marine Works Japan, Ltd., Yokosuka, Kanagawa, Japan
| | - Seiji SUGITA
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Ayako SUZUKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Marine Works Japan, Ltd., Yokosuka, Kanagawa, Japan
| | - Tomohiro USUI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Toru YADA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Daiki YAMAMOTO
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Kasumi YOGATA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Miwa YOSHITAKE
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | | | - Atsushi FUJII
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Masahiko HAYAKAWA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Naoyuki HIRATA
- Graduate School of Science, Kobe University, Kobe, Hyogo, Japan
| | - Naru HIRATA
- Faculty of Computer Science and Engineering, The University of Aizu, Aizu-Wakamatsu, Fukushima, Japan
| | - Rie HONDA
- Faculty of Science and Technology, Kochi University, Kochi, Japan
| | - Chikatoshi HONDA
- Faculty of Computer Science and Engineering, The University of Aizu, Aizu-Wakamatsu, Fukushima, Japan
| | - Satoshi HOSODA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Yu-ichi IIJIMA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Hitoshi IKEDA
- Research and Development Directorate, JAXA, Sagamihara, Kanagawa, Japan
| | - Masateru ISHIGURO
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Yoshiaki ISHIHARA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Takahiro IWATA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Kosuke KAWAHARA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Shota KIKUCHI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Kohei KITAZATO
- Faculty of Computer Science and Engineering, The University of Aizu, Aizu-Wakamatsu, Fukushima, Japan
| | - Koji MATSUMOTO
- National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan
| | - Moe MATSUOKA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Observatoire de Paris, Meudon, France
| | - Tatsuhiro MICHIKAMI
- Faculty of Engineering, Kindai University, Higashi-Hiroshima, Hiroshima, Japan
| | - Yuya MIMASU
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Akira MIURA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Tomokatsu MOROTA
- Graduate School of Environmental Studies, Nagoya University, Nagoya, Aichi, Japan
| | - Satoru NAKAZAWA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Noriyuki NAMIKI
- National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan
| | - Hirotomo NODA
- National Astronomical Observatory of Japan, Mitaka, Tokyo, Japan
| | - Rina NOGUCHI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Faculty of Science, Niigata University, Niigata, Japan
| | - Naoko OGAWA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- JAXA Space Exploration Center, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Kazunori OGAWA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Chisato OKAMOTO
- Graduate School of Science, Kobe University, Kobe, Hyogo, Japan
| | - Go ONO
- Research and Development Directorate, JAXA, Sagamihara, Kanagawa, Japan
| | - Masanobu OZAKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Takanao SAIKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | | | - Hirotaka SAWADA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Hiroki SENSHU
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Yuri SHIMAKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Kei SHIRAI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Graduate School of Science, Kobe University, Kobe, Hyogo, Japan
| | - Yuto TAKEI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Hiroshi TAKEUCHI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Satoshi TANAKA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
- The University of Tokyo, Kashiwa, Chiba, Japan
| | - Eri TATSUMI
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
- Instituto de Astrofisica de Canarias, University of La Laguna, Tenerife, Spain
| | - Fuyuto TERUI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Faculty of Engineering, Kanagawa Institute of Technology, Atsugi, Kanagawa, Japan
| | - Ryudo TSUKIZAKI
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Koji WADA
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Manabu YAMADA
- Planetary Exploration Research Center (PERC), Chiba Institute of Technology, Narashino, Chiba, Japan
| | - Tetsuya YAMADA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Yukio YAMAMOTO
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Hajime YANO
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Yasuhiro YOKOTA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Keisuke YOSHIHARA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Makoto YOSHIKAWA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, Japan
| | - Kent YOSHIKAWA
- Research and Development Directorate, JAXA, Sagamihara, Kanagawa, Japan
| | - Masaki FUJIMOTO
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
| | - Sei-ichiro WATANABE
- Graduate School of Environmental Studies, Nagoya University, Nagoya, Aichi, Japan
| | - Yuichi TSUDA
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Kanagawa, Japan
- Graduate School of Science, The University of Tokyo, Tokyo, Japan
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Particle Size-Frequency Distributions of the OSIRIS-REx Candidate Sample Sites on Asteroid (101955) Bennu. REMOTE SENSING 2021. [DOI: 10.3390/rs13071315] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
We manually mapped particles ranging in longest axis from 0.3 cm to 95 m on (101955) Bennu for the Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) asteroid sample return mission. This enabled the mission to identify candidate sample collection sites and shed light on the processes that have shaped the surface of this rubble-pile asteroid. Building on a global survey of particles, we used higher-resolution data from regional observations to calculate particle size-frequency distributions (PSFDs) and assess the viability of four candidate sites for sample collection (presence of unobstructed particles ≤ 2 cm). The four candidate sites have common characteristics: each is situated within a crater with a relative abundance of sampleable material. Their PSFDs, however, indicate that each site has experienced different geologic processing. The PSFD power-law slopes range from −3.0 ± 0.2 to −2.3 ± 0.1 across the four sites, based on images with a 0.01-m pixel scale. These values are consistent with, or shallower than, the global survey measurements. At one site, Osprey, the particle packing density appears to reach geometric saturation. We evaluate the uncertainty in these measurements and discuss their implications for other remotely sensed and mapped particles, and their importance to OSIRIS-REx sampling operations.
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Goodrich CA, Sanborn ME, Yin QZ, Kohl I, Frank D, Daly RT, Walsh KJ, Zolensky ME, Young ERD, Jenniskens P, Shaddad MH. Chromium Isotopic Evidence for Mixing of NC and CC Reservoirs in Polymict Ureilites: Implications for Dynamical Models of the Early Solar System. THE PLANETARY SCIENCE JOURNAL 2021; 2:13. [PMID: 33681766 PMCID: PMC7931809 DOI: 10.3847/psj/abd258] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Nucleosynthetic isotope anomalies show that the first few million years of solar system history were characterized by two distinct cosmochemical reservoirs, CC (carbonaceous chondrites and related differentiated meteorites) and NC (the terrestrial planets and all other groups of chondrites and differentiated meteorites), widely interpreted to correspond to the outer and inner solar system, respectively. At some point, however, bulk CC and NC materials became mixed, and several dynamical models offer explanations for how and when this occurred. We use xenoliths of CC materials in polymict ureilite (NC) breccias to test the applicability of such models. Polymict ureilites represent regolith on ureilitic asteroids but contain carbonaceous chondrite-like xenoliths. We present the first 54Cr isotope data for such clasts, which, combined with oxygen and hydrogen isotopes, show that they are unique CC materials that became mixed with NC materials in these breccias. It has been suggested that such xenoliths were implanted into ureilites by outer solar system bodies migrating into the inner solar system during the gaseous disk phase ~3-5 Myr after CAI, as in the "Grand Tack" model. However, combined textural, petrologic, and spectroscopic observations suggest that they were added to ureilitic regolith at ~50-60 Myr after CAI, along with ordinary, enstatite, and Rumuruti-type chondrites, as a result of breakup of multiple parent bodies in the asteroid belt at this time. This is consistent with models for an early instability of the giant planets. The C-type asteroids from which the xenoliths were derived were already present in inner solar system orbits.
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Affiliation(s)
- Cyrena A Goodrich
- Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058 USA
| | - Matthew E Sanborn
- Department of Earth and Planetary Sciences, University of California at Davis, Davis, CA 95616 USA
| | - Qing-Zhu Yin
- Department of Earth and Planetary Sciences, University of California at Davis, Davis, CA 95616 USA
| | - Issaku Kohl
- Department of Earth and Planetary Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095 USA
| | - David Frank
- Hawai'i Institute of Geophysics and Planetology, Department of Earth Sciences, University of Hawai'i at Mānoa, Honolulu HI 96822 USA
| | - R Terik Daly
- The Johns Hopkins University Applied Physics Laboratory 11100 Johns Hopkins Road
| | - Kevin J Walsh
- Southwest Research Institute, 1050 Walnut St. Suite 300, Boulder, CO 80302 USA
| | - Michael E Zolensky
- Astromaterials Research and Exploration Science, NASA-Johnson Space Center Houston, TX 77058 USA
| | - Edward R D Young
- Department of Earth and Planetary Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095 USA
| | | | - Muawia H Shaddad
- Physics Department, University of Khartoum, Khartoum 11115 Sudan
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Bennu's near-Earth lifetime of 1.75 million years inferred from craters on its boulders. Nature 2020; 587:205-209. [PMID: 33106686 DOI: 10.1038/s41586-020-2846-z] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Accepted: 09/15/2020] [Indexed: 11/08/2022]
Abstract
An asteroid's history is determined in large part by its strength against collisions with other objects1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5. In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7. It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu's metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years.
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7
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Michel P, Ballouz RL, Barnouin OS, Jutzi M, Walsh KJ, May BH, Manzoni C, Richardson DC, Schwartz SR, Sugita S, Watanabe S, Miyamoto H, Hirabayashi M, Bottke WF, Connolly HC, Yoshikawa M, Lauretta DS. Collisional formation of top-shaped asteroids and implications for the origins of Ryugu and Bennu. Nat Commun 2020; 11:2655. [PMID: 32461569 PMCID: PMC7253434 DOI: 10.1038/s41467-020-16433-z] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2019] [Accepted: 04/29/2020] [Indexed: 11/24/2022] Open
Abstract
Asteroid shapes and hydration levels can serve as tracers of their history and origin. For instance, the asteroids (162173) Ryugu and (101955) Bennu have an oblate spheroidal shape with a pronounced equator, but contain different surface hydration levels. Here we show, through numerical simulations of large asteroid disruptions, that oblate spheroids, some of which have a pronounced equator defining a spinning top shape, can form directly through gravitational reaccumulation. We further show that rubble piles formed in a single disruption can have similar porosities but variable degrees of hydration. The direct formation of top shapes from single disruption alone can explain the relatively old crater-retention ages of the equatorial features of Ryugu and Bennu. Two separate parent-body disruptions are not necessarily required to explain their different hydration levels.
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Affiliation(s)
- P Michel
- Universite Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de la Recherche Scientifique, Laboratoire Lagrange, Nice, France.
| | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M Jutzi
- Physics Institute, University of Bern, NCCR PlanetS, Gesellsschaftsstrasse 6, 3012, Bern, Switzerland
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - B H May
- London Stereoscopic Company, London, UK
| | - C Manzoni
- London Stereoscopic Company, London, UK
| | - D C Richardson
- Department of Astronomy, University of Maryland, College Park, MD, USA
| | - S R Schwartz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - S Sugita
- Department of Earth and Planetary Science, School of Science, The University of Tokyo, Tokyo, Japan
| | - S Watanabe
- Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
| | - H Miyamoto
- Department of System Innovation, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - M Hirabayashi
- Department of Aerospace Engineering, Auburn University, Auburn, AL, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - H C Connolly
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
- Department of Geology, School of Earth and Environment, Rowan University, Glassboro, NJ, USA
| | - M Yoshikawa
- Institute of Space and Astronautical Sciences, JAXA, Sagamihara, Japan
| | - D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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8
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Vourc'h T, Léopoldès J, Peerhossaini H. Clustering of bacteria with heterogeneous motility. Phys Rev E 2020; 101:022612. [PMID: 32168693 DOI: 10.1103/physreve.101.022612] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 02/05/2020] [Indexed: 11/07/2022]
Abstract
We study the clustering of a model cyanobacterium Synechocystis into microcolonies. The bacteria are allowed to diffuse onto surfaces of different hardness and interact with the others by aggregation and detachment. We find that soft surfaces give rise to more microcolonies than hard ones. This effect is related to the amount of heterogeneity of bacteria's dynamics as given by the proportion of motile cells. A kinetic model that emphasizes specific interactions between cells, complemented by extensive numerical simulations considering various amounts of motility, describes the experimental results adequately. The high proportion of motile cells enhances dispersion rather than aggregation.
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Affiliation(s)
- T Vourc'h
- Laboratoire AstroParticules et Cosmologie, CNRS, Université Paris-Diderot, Université de Paris, 5 rue Thomas Mann 75013 Paris, France
| | - J Léopoldès
- ESPCI Paris, PSL Research University, CNRS, Institut Langevin, 1 rue Jussieu, F-75005 Paris, France.,Université Paris-Est Marne-la-Vallée, 5 Bd Descartes, Champs sur Marne, Marne-la-Vallée Cedex 2, France
| | - H Peerhossaini
- Laboratoire AstroParticules et Cosmologie, CNRS, Université Paris-Diderot, Université de Paris, 5 rue Thomas Mann 75013 Paris, France.,Mechanics of Active Fluids Laboratory, Department of Civil and Environmental Engineering, Department of Mechanical and Materials Engineering, University of Western Ontario, London, Ontario, Canada N6A3K7
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9
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Goodrich CA, Zolensky ME, Fioretti AM, Shaddad MH, Downes H, Hiroi T, Kohl I, Young ED, Kita NT, Hamilton VE, Riebe MEI, Busemann H, Macke RJ, Fries M, Ross DK, Jenniskens P. The First Samples from Almahata Sitta Showing Contacts Between Ureilitic and Chondritic Lithologies: Implications for the Structure and Composition of Asteroid 2008 TC 3. METEORITICS & PLANETARY SCIENCE 2019; 54:2769-2813. [PMID: 33716489 PMCID: PMC7954227 DOI: 10.1111/maps.13390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 08/17/2019] [Indexed: 06/12/2023]
Abstract
Almahata Sitta (AhS), an anomalous polymict ureilite, is the first meteorite observed to originate from a spectrally classified asteroid (2008 TC3). However, correlating properties of the meteorite with those of the asteroid is not straightforward because the AhS stones are diverse types. Of those studied prior to this work, 70-80% are ureilites (achondrites) and 20-30% are various types of chondrites. Asteroid 2008 TC3 was a heterogeneous breccia that disintegrated in the atmosphere, with its clasts landing on Earth as individual stones and most of its mass lost. We describe AhS 91A and AhS 671, which are the first AhS stones to show contacts between ureilitic and chondritic materials and provide direct information about the structure and composition of asteroid 2008 TC3. AhS 91A and AhS 671 are friable breccias, consisting of a C1 lithology that encloses rounded to angular clasts (<10 μm to 3 mm) of olivine, pyroxenes, plagioclase, graphite, and metal-sulfide, as well as chondrules (~130-600 μm) and chondrule fragments. The C1 material consists of fine-grained phyllosilicates (serpentine and saponite) and amorphous material, magnetite, breunnerite, dolomite, fayalitic olivine (Fo 28-42), an unidentified Ca-rich silicate phase, Fe,Ni sulfides, and minor Ca-phosphate and ilmenite. It has similarities to CI1 but shows evidence of heterogeneous thermal metamorphism. Its bulk oxygen isotope composition (δ18O = 13.53‰, δ17O = 8.93‰) is unlike that of any known chondrite, but similar to compositions of several CC-like clasts in typical polymict ureilites. Its Cr isotope composition is unlike that of any known meteorite. The enclosed clasts and chondrules do not belong to the C1 lithology. The olivine (Fo 75-88), pyroxenes (pigeonite of Wo ~10 and orthopyroxene of Wo ~4.6), plagioclase, graphite, and some metal-sulfide are ureilitic, based on mineral compositions, textures, and oxygen isotope compositions, and represent at least six distinct ureilitic lithologies. The chondrules are probably derived from type 3 OC and/or CC, based on mineral and oxygen isotope compositions. Some of the metal-sulfide clasts are derived from EC. AhS 91A and AhS 671 are plausible representatives of the bulk of the asteroid that was lost. Reflectance spectra of AhS 91A are dark (reflectance ~0.04-0.05) and relatively featureless in VNIR, and have an ~2.7 μm absorption band due to OH- in phyllosilicates. Spectral modeling, using mixtures of laboratory VNIR reflectance spectra of AhS stones to fit the F-type spectrum of the asteroid, suggests that 2008 TC3 consisted mainly of ureilitic and AhS 91A-like materials, with as much as 40-70% of the latter, and <10% of OC, EC and other meteorite types. The bulk density of AhS 91A (2.35 ± 0.05 g/cm3) is lower than bulk densities of other AhS stones, and closer to estimates for the asteroid (~1.7-2.2 g/cm3). Its porosity (36%) is near the low end of estimates for the asteroid (33-50%), suggesting significant macroporosity. The textures of AhS 91A and AhS 671 (finely comminuted clasts of disparate materials intimately mixed) support formation of 2008 TC3 in a regolith environment. AhS 91A and AhS 671 could represent a volume of regolith formed when a CC-like body impacted into already well-gardened ureilitic + impactor-derived debris. AhS 91A bulk samples do not show a solar wind (SW) component, so they represent sub-surface layers. AhS 91A has a lower cosmic ray exposure (CRE) age (~5-9 Ma) than previously studied AhS stones (11-22 Ma). The spread in CRE ages argues for irradiation in a regolith environment. AhS 91A and AhS 671 show that ureilitic asteroids could have detectable ~2.7 μm absorption bands.
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Affiliation(s)
- Cyrena Anne Goodrich
- Lunar and Planetary Institute, Universities Space Research Association, 3600 Bay Area Blvd, Houston, TX 77058 USA
| | - Michael E Zolensky
- Astromaterials Research and Exploration Science, NASA-Johnson Space Center Houston, TX 77058 USA
| | | | - Muawia H Shaddad
- Physics Department, University of Khartoum, Khartoum 11115 Sudan
| | - Hilary Downes
- Department of Earth and Planetary Sciences, Birkbeck, University of London, Malet Street, Bloomsbury, London WC1E 7HX UK
| | - Takahiro Hiroi
- Department of Geological Sciences, Brown University, Providence, RI 02912, USA
| | - Issaku Kohl
- Department of Earth and Planetary Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095 USA
| | - Edward D Young
- Department of Earth and Planetary Sciences, University of California at Los Angeles, 595 Charles Young Drive East, Los Angeles, CA 90095 USA
| | - Noriko T Kita
- Wisc-SIMS Laboratory, Department of Geoscience, University of Wisconsin-Madison, 1215 West Dayton Street, Madison, WI 53706 USA
| | - Victoria E Hamilton
- Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder Colorado 80302 USA
| | - My E I Riebe
- Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Rd NW, Washington, DC 20015, USA
- Institute for Geochemistry and Petrology, ETH Zürich, Clausiusstrasse 25, CH-8092 Zürich, Switzerland
| | - Henner Busemann
- Institute for Geochemistry and Petrology, ETH Zürich, Clausiusstrasse 25, CH-8092 Zürich, Switzerland
| | | | - M Fries
- Astromaterials Research and Exploration Science, NASA-Johnson Space Center Houston, TX 77058 USA
| | - D Kent Ross
- Jacobs-JETS, University of Texas at El Paso, at NASA-JSC, Houston, TX 77058 USA
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10
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Chen S, Chai HW, He AM, Tschentscher T, Cai Y, Luo SN. Resolving dynamic fragmentation of liquids at the nanoscale with ultrafast small-angle X-ray scattering. JOURNAL OF SYNCHROTRON RADIATION 2019; 26:1412-1421. [PMID: 31490129 DOI: 10.1107/s160057751900732x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/20/2019] [Indexed: 06/10/2023]
Abstract
High-brightness coherent ultrashort X-ray free-electron lasers (XFELs) are promising in resolving nanoscale structures at the highest temporal resolution (∼10 fs). The feasibility is explored of resolving ultrafast fragmentation of liquids at the nanoscale with single-shot small-angle X-ray scattering (SAXS) on the basis of large-scale molecular dynamics simulations. Fragmentation of liquid sheets under adiabatic expansion is investigated. From the simulated SAXS patterns, particle-volume size distributions are obtained with the regularization method and average particle sizes with the weighted Guinier method, at different expansion rates. The particle sizes obtained from simulated SAXS are in excellent agreement with direct cluster analysis. Pulse-width effects on SAXS measurements are examined. The results demonstrate the feasibility of resolving the nanoscale dynamics of fragmentation and similar processes with SAXS, and provide guidance for future XFEL experiments and data interpretation.
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Affiliation(s)
- Sen Chen
- The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China
| | - Hai Wei Chai
- The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China
| | - An Min He
- Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China
| | | | - Yang Cai
- The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China
| | - Sheng Nian Luo
- The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China
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11
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History of the Terminal Cataclysm Paradigm: Epistemology of a Planetary Bombardment That Never (?) Happened. GEOSCIENCES 2019. [DOI: 10.3390/geosciences9070285] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This study examines the history of the paradigm concerning a lunar (or solar-systemwide)terminal cataclysm (also called “Late Heavy Bombardment” or LHB), a putative, brief spikein impacts at ~3.9 Ga ago, preceded by low impact rates. We examine origin of the ideas, why theywere accepted, and why the ideas are currently being seriously revised, if not abandoned. Thepaper is divided into the following sections:1. Overview of paradigm.2. Pre-Apollo views (1949-1969).3. Initial suggestions of cataclysm (ca. 1974).4. Ironies.5. Alternative suggestions, megaregolith evolution (1970s).6. Impact melt rocks “establish” cataclysm (1990).7. Imbrium redux (ca. 1998).8. Impact melt clasts (early 2000s).9. Dating of front-side lunar basins?10. Dynamical models “explain” the cataclysm (c. 2000s).11. Asteroids as a test case.12. Impact melts predating 4.0 Ga ago (ca. 2008-present.).13. Biological issues.14. Growing doubts (ca. 1994-2014).15. Evolving Dynamical Models (ca. 2001-present).16. Connections to lunar origin.17. Dismantling the paradigm (2015-2018).18. “Megaregolith Evolution Model” for explaining the data.19. Conclusions and new directions for future work.The author hopes that this open-access discussion may prove useful for classroom discussionsof how science moves forward through self-correction of hypotheses.
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12
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Watanabe S, Hirabayashi M, Hirata N, Hirata N, Noguchi R, Shimaki Y, Ikeda H, Tatsumi E, Yoshikawa M, Kikuchi S, Yabuta H, Nakamura T, Tachibana S, Ishihara Y, Morota T, Kitazato K, Sakatani N, Matsumoto K, Wada K, Senshu H, Honda C, Michikami T, Takeuchi H, Kouyama T, Honda R, Kameda S, Fuse T, Miyamoto H, Komatsu G, Sugita S, Okada T, Namiki N, Arakawa M, Ishiguro M, Abe M, Gaskell R, Palmer E, Barnouin OS, Michel P, French AS, McMahon JW, Scheeres DJ, Abell PA, Yamamoto Y, Tanaka S, Shirai K, Matsuoka M, Yamada M, Yokota Y, Suzuki H, Yoshioka K, Cho Y, Tanaka S, Nishikawa N, Sugiyama T, Kikuchi H, Hemmi R, Yamaguchi T, Ogawa N, Ono G, Mimasu Y, Yoshikawa K, Takahashi T, Takei Y, Fujii A, Hirose C, Iwata T, Hayakawa M, Hosoda S, Mori O, Sawada H, Shimada T, Soldini S, Yano H, Tsukizaki R, Ozaki M, Iijima Y, Ogawa K, Fujimoto M, Ho TM, Moussi A, Jaumann R, Bibring JP, Krause C, Terui F, Saiki T, Nakazawa S, Tsuda Y. Hayabusa2 arrives at the carbonaceous asteroid 162173 Ryugu-A spinning top-shaped rubble pile. Science 2019; 364:268-272. [PMID: 30890588 DOI: 10.1126/science.aav8032] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Accepted: 03/07/2019] [Indexed: 11/02/2022]
Abstract
The Hayabusa2 spacecraft arrived at the near-Earth carbonaceous asteroid 162173 Ryugu in 2018. We present Hayabusa2 observations of Ryugu's shape, mass, and geomorphology. Ryugu has an oblate "spinning top" shape, with a prominent circular equatorial ridge. Its bulk density, 1.19 ± 0.02 grams per cubic centimeter, indicates a high-porosity (>50%) interior. Large surface boulders suggest a rubble-pile structure. Surface slope analysis shows Ryugu's shape may have been produced from having once spun at twice the current rate. Coupled with the observed global material homogeneity, this suggests that Ryugu was reshaped by centrifugally induced deformation during a period of rapid rotation. From these remote-sensing investigations, we identified a suitable sample collection site on the equatorial ridge.
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Affiliation(s)
- S Watanabe
- Nagoya University, Nagoya 464-8601, Japan. .,Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | | | - N Hirata
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - Na Hirata
- Kobe University, Kobe 657-8501, Japan
| | - R Noguchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Shimaki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - H Ikeda
- Research and Development Directorate, JAXA, Sagamihara 252-5210, Japan
| | - E Tatsumi
- University of Tokyo, Tokyo 113-0033, Japan
| | - M Yoshikawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - S Kikuchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - H Yabuta
- Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - T Nakamura
- Tohoku University, Sendai 980-8578, Japan
| | - S Tachibana
- University of Tokyo, Tokyo 113-0033, Japan.,Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Ishihara
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T Morota
- Nagoya University, Nagoya 464-8601, Japan
| | - K Kitazato
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - N Sakatani
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - K Matsumoto
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - K Wada
- Chiba Institute of Technology, Narashino 275-0016, Japan
| | - H Senshu
- Chiba Institute of Technology, Narashino 275-0016, Japan
| | - C Honda
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - T Michikami
- Kindai University, Higashi-Hiroshima 739-2116, Japan
| | - H Takeuchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - T Kouyama
- National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064 Japan
| | - R Honda
- Kochi University, Kochi 780-8520, Japan
| | - S Kameda
- Rikkyo University, Tokyo 171-8501, Japan
| | - T Fuse
- National Institute of Information and Communications Technology, Kashima 314-8501, Japan
| | - H Miyamoto
- University of Tokyo, Tokyo 113-0033, Japan
| | - G Komatsu
- Università d'Annunzio, 65127 Pescara, Italy.,Chiba Institute of Technology, Narashino 275-0016, Japan
| | - S Sugita
- University of Tokyo, Tokyo 113-0033, Japan
| | - T Okada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,University of Tokyo, Tokyo 113-0033, Japan
| | - N Namiki
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - M Arakawa
- Kobe University, Kobe 657-8501, Japan
| | - M Ishiguro
- Seoul National University, Seoul 08826, Korea
| | - M Abe
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - R Gaskell
- Planetary Science Institute, Tucson, AZ 85710, USA
| | - E Palmer
- Planetary Science Institute, Tucson, AZ 85710, USA
| | - O S Barnouin
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de la Recherche Scientifique (CNRS), Laboratoire Lagrange, 06304 Nice, France
| | - A S French
- University of Colorado, Boulder, CO 80309, USA
| | - J W McMahon
- University of Colorado, Boulder, CO 80309, USA
| | | | - P A Abell
- NASA Johnson Space Center, Houston, TX 77058, USA
| | - Y Yamamoto
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - S Tanaka
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - K Shirai
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - M Matsuoka
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - M Yamada
- Chiba Institute of Technology, Narashino 275-0016, Japan
| | - Y Yokota
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,Kochi University, Kochi 780-8520, Japan
| | - H Suzuki
- Meiji University, Kawasaki 214-8571, Japan
| | - K Yoshioka
- University of Tokyo, Tokyo 113-0033, Japan
| | - Y Cho
- University of Tokyo, Tokyo 113-0033, Japan
| | - S Tanaka
- Kobe University, Kobe 657-8501, Japan
| | | | - T Sugiyama
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - H Kikuchi
- University of Tokyo, Tokyo 113-0033, Japan
| | - R Hemmi
- University of Tokyo, Tokyo 113-0033, Japan
| | - T Yamaguchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - N Ogawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - G Ono
- Research and Development Directorate, JAXA, Sagamihara 252-5210, Japan
| | - Y Mimasu
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - K Yoshikawa
- Research and Development Directorate, JAXA, Sagamihara 252-5210, Japan
| | - T Takahashi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Takei
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - A Fujii
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - C Hirose
- Research and Development Directorate, JAXA, Sagamihara 252-5210, Japan
| | - T Iwata
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - M Hayakawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - S Hosoda
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - O Mori
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - H Sawada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T Shimada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - S Soldini
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - H Yano
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - R Tsukizaki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - M Ozaki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - Y Iijima
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - K Ogawa
- Kobe University, Kobe 657-8501, Japan
| | - M Fujimoto
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T-M Ho
- DLR (German Aerospace Center), Institute of Space Systems, 28359 Bremen, Germany
| | - A Moussi
- Centre National d'Etudes Spatiales (CNES), 31401 Toulouse, France
| | - R Jaumann
- DLR, Institute of Planetary Research, 12489 Berlin-Adlershof, Germany
| | - J-P Bibring
- Institute d'Astrophysique Spatiale, 91405 Orsay, France
| | - C Krause
- DLR, Microgravity User Support Center, 51147 Cologne, Germany
| | - F Terui
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T Saiki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - S Nakazawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Tsuda
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
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13
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Thermal and impact histories of 25143 Itokawa recorded in Hayabusa particles. Sci Rep 2018; 8:11806. [PMID: 30087407 PMCID: PMC6081429 DOI: 10.1038/s41598-018-30192-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 07/23/2018] [Indexed: 11/08/2022] Open
Abstract
Understanding the origin and evolution of near-Earth asteroids (NEAs) is an issue of scientific interest and practical importance because NEAs are potentially hazardous to the Earth. However, when and how NEAs formed and their evolutionary history remain enigmas. Here, we report the U-Pb systematics of Itokawa particles for the first time. Ion microprobe analyses of seven phosphate grains from a single particle provide an isochron age of 4.64 ± 0.18 billion years (1σ). This ancient phosphate age is thought to represent the thermal metamorphism of Itokawa's parent body, which is identical to that of typical LL chondrites. In addition, the incorporation of other particles suggests that a significant shock event might have occurred 1.51 ± 0.85 billion years ago (1σ), which is significantly different from the shock ages of 4.2 billion years of the majority of shocked LL chondrites and similar to that of the Chelyabinsk meteorite. Combining these data with recent Ar-Ar studies on particles from a different landing site, we conclude that a globally intense impact, possibly a catastrophic event, occurred ca. 1.4 Ga ago. This conclusion enables us to establish constraints on the timescale of asteroid disruption frequency, the validity of the crater chronology and the mean lifetime of small NEAs.
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Manrique PD, Zheng M, Cao Z, Restrepo EM, Johnson NF. Generalized Gelation Theory Describes Onset of Online Extremist Support. PHYSICAL REVIEW LETTERS 2018; 121:048301. [PMID: 30095930 DOI: 10.1103/physrevlett.121.048301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 06/15/2018] [Indexed: 05/11/2023]
Abstract
We introduce a generalized form of gelation theory that incorporates individual heterogeneity and show that it can explain the asynchronous, sudden appearance and growth of online extremist groups supporting ISIS (so-called Islamic State) that emerged globally post-2014. The theory predicts how heterogeneity impacts their onset times and growth profiles and suggests that online extremist groups present a broad distribution of heterogeneity-dependent aggregation mechanisms centered around homophily. The good agreement between the theory and empirical data suggests that existing strategies aiming to defeat online extremism under the assumption that it is driven by a few "bad apples" are misguided. More generally, this generalized theory should apply to a range of real-world systems featuring aggregation among heterogeneous objects.
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Affiliation(s)
- Pedro D Manrique
- Physics Department, University of Miami, Coral Gables, Florida 33126, USA
| | - Minzhang Zheng
- Physics Department, University of Miami, Coral Gables, Florida 33126, USA
| | - Zhenfeng Cao
- Physics Department, University of Miami, Coral Gables, Florida 33126, USA
| | - Elvira Maria Restrepo
- Elliott School of International Affairs, George Washington University, Washington, DC 20052, USA
| | - Neil F Johnson
- Physics Department, George Washington University, Washington, DC 20052, USA
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First known terrestrial impact of a binary asteroid from a main belt breakup event. Sci Rep 2014; 4:6724. [PMID: 25340551 PMCID: PMC5381370 DOI: 10.1038/srep06724] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Accepted: 09/25/2014] [Indexed: 11/08/2022] Open
Abstract
Approximately 470 million years ago one of the largest cosmic catastrophes occurred in our solar system since the accretion of the planets. A 200-km large asteroid was disrupted by a collision in the Main Asteroid Belt, which spawned fragments into Earth crossing orbits. This had tremendous consequences for the meteorite production and cratering rate during several millions of years following the event. The 7.5-km wide Lockne crater, central Sweden, is known to be a member of this family. We here provide evidence that Lockne and its nearby companion, the 0.7-km diameter, contemporaneous, Målingen crater, formed by the impact of a binary, presumably ‘rubble pile’ asteroid. This newly discovered crater doublet provides a unique reference for impacts by combined, and poorly consolidated projectiles, as well as for the development of binary asteroids.
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Rotational breakup as the origin of small binary asteroids. Nature 2008; 454:188-91. [PMID: 18615078 DOI: 10.1038/nature07078] [Citation(s) in RCA: 288] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2008] [Accepted: 04/29/2008] [Indexed: 11/09/2022]
Abstract
Asteroids with satellites are observed throughout the Solar System, from subkilometre near-Earth asteroid pairs to systems of large and distant bodies in the Kuiper belt. The smallest and closest systems are found among the near-Earth and small inner main-belt asteroids, which typically have rapidly rotating primaries and close secondaries on circular orbits. About 15 per cent of near-Earth and main-belt asteroids with diameters under 10 km have satellites. The mechanism that forms such similar binaries in these two dynamically different populations was hitherto unclear. Here we show that these binaries are created by the slow spinup of a 'rubble pile' asteroid by means of the thermal YORP (Yarkovsky-O'Keefe-Radzievskii-Paddack) effect. We find that mass shed from the equator of a critically spinning body accretes into a satellite if the material is collisionally dissipative and the primary maintains a low equatorial elongation. The satellite forms mostly from material originating near the primary's surface and enters into a close, low-eccentricity orbit. The properties of binaries produced by our model match those currently observed in the small near-Earth and main-belt asteroid populations, including 1999 KW(4) (refs 3, 4).
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Marchis F, Descamps P, Hestroffer D, Berthier J. Discovery of the triple asteroidal system 87 Sylvia. Nature 2005; 436:822-4. [PMID: 16094362 DOI: 10.1038/nature04018] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2005] [Accepted: 07/06/2005] [Indexed: 11/08/2022]
Abstract
After decades of speculation, the existence of binary asteroids has been observationally confirmed, with examples in all minor planet populations. However, no triple systems have hitherto been discovered. Here we report the unambiguous detection of a triple asteroidal system in the main belt, composed of a 280-km primary (87 Sylvia) and two small moonlets orbiting at 710 and 1,360 km. We estimate their orbital elements and use them to refine the shape of the primary body. Both orbits are equatorial, circular and prograde, suggesting a common origin. Using the orbital information to estimate its mass and density, 87 Sylvia appears to have a rubble-pile structure with a porosity of 25-60 per cent. The system was most probably formed through the disruptive collision of a parent asteroid, with the new primary resulting from accretion of fragments, while the moonlets are formed from the debris, as has been predicted previously.
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Affiliation(s)
- Franck Marchis
- University of California at Berkeley, Department of Astronomy, 601 Campbell Hall, Berkeley, California 94720, USA.
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Koon WS, Marsden JE, Ross SD, Lo M, Scheeres DJ. Geometric mechanics and the dynamics of asteroid pairs. Ann N Y Acad Sci 2004; 1017:11-38. [PMID: 15220138 DOI: 10.1196/annals.1311.002] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The purpose of this paper is to describe the general setting for the application of techniques from geometric mechanics and dynamical systems to the problem of asteroid pairs. The paper also gives some preliminary results on transport calculations and the associated problem of calculating binary asteroid escape rates. The dynamics of an asteroid pair, consisting of two irregularly shaped asteroids interacting through their gravitational potential is an example of a full-body problem or FBP in which two or more extended bodies interact. One of the interesting features of the binary asteroid problem is that there is coupling between their translational and rotational degrees of freedom. General FBPs have a wide range of other interesting aspects as well, including the 6-DOF guidance, control, and dynamics of vehicles, the dynamics of interacting or ionizing molecules, the evolution of small body, planetary, or stellar systems, and almost any other problem in which distributed bodies interact with each other or with an external field. This paper focuses on the specific case of asteroid pairs using techniques that are generally applicable to many other FBPs. This particular full two-body problem (F2BP) concerns the dynamical evolution of two rigid bodies mutually interacting via a gravitational field. Motivation comes from planetary science, where these interactions play a key role in the evolution of asteroid rotation states and binary asteroid systems. The techniques that are applied to this problem fall into two main categories. The first is the use of geometric mechanics to obtain a description of the reduced phase space, which opens the door to a number of powerful techniques, such as the energy-momentum method for determining the stability of equilibria and the use of variational integrators for greater accuracy in simulation. Second, techniques from computational dynamic systems are used to determine phase space structures that are important for transport phenomena and dynamic evolution.
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Affiliation(s)
- Wang-Sang Koon
- Control and Dynamical Systems 107-81, Caltech, Pasadena, CA 91125, USA.
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20
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Jedicke R, Nesvorný D, Whiteley R, Ivezić Z Z, Jurić M. An age-colour relationship for main-belt S-complex asteroids. Nature 2004; 429:275-7. [PMID: 15152246 DOI: 10.1038/nature02578] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2003] [Accepted: 04/07/2004] [Indexed: 11/09/2022]
Abstract
Asteroid collisions in the main belt eject fragments that may eventually land on Earth as meteorites. It has therefore been a long-standing puzzle in planetary science that laboratory spectra of the most populous class of meteorite (ordinary chondrites, OC) do not match the remotely observed surface spectra of their presumed (S-complex) asteroidal parent bodies. One of the proposed solutions to this perplexing observation is that 'space weathering' modifies the exposed planetary surfaces over time through a variety of processes (such as solar and cosmic ray bombardment, micro-meteorite bombardment, and so on). Space weathering has been observed on lunar samples, in Earth-based laboratory experiments, and there is good evidence from spacecraft data that the process is active on asteroid surfaces. Here, we present a measurement of the rate of space weathering on S-complex main-belt asteroids using a relationship between the ages of asteroid families and their colours. Extrapolating this age-colour relationship to very young ages yields a good match to the colour of freshly cut OC meteorite samples, lending strong support to a genetic relationship between them and the S-complex asteroids.
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Affiliation(s)
- Robert Jedicke
- Institute for Astronomy, University of Hawaii, Honolulu, Hawaii 96822, USA.
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22
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Vokrouhlický D, Nesvorný D, Bottke WF. The vector alignments of asteroid spins by thermal torques. Nature 2003; 425:147-51. [PMID: 12968171 DOI: 10.1038/nature01948] [Citation(s) in RCA: 155] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Accepted: 07/28/2003] [Indexed: 11/09/2022]
Abstract
Collisions have been thought to be the dominant process altering asteroid rotations, but recent observations of the Koronis family of asteroids suggest that this may be incorrect. This group of asteroids was formed in a catastrophic collision several billion years ago; in the intervening period their rotational axes should have become nearly random because of subsequent collisions, with spin rates that follow a maxwellian distribution. What is seen, however, is that the observed family members with prograde spins have nearly identical periods (7.5-9.5 h) and obliquities between 42 and 50 degrees, while those with retrograde spins have obliquities between 154 and 169 degrees with periods either <5 h or >13 h. Here we show that these non-random orientations and spin rates can be explained by 'thermal torques' (arising from differential solar heating), which modify the spin states over time. In some cases, the asteroids become trapped in spin-orbit resonances. Our results suggest that thermal torques may be more important than collisions in changing the spin states (and possibly shapes) of asteroids with diameters <40 km.
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Michel P, Benz W, Richardson DC. Disruption of fragmented parent bodies as the origin of asteroid families. Nature 2003; 421:608-11. [PMID: 12571589 DOI: 10.1038/nature01364] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2002] [Accepted: 12/05/2002] [Indexed: 11/08/2022]
Abstract
Asteroid families are groups of small bodies that share certain orbit and spectral properties. More than 20 families have now been identified, each believed to have resulted from the collisional break-up of a large parent body in a regime where gravity controls the outcome of the collision more than the material strength of the rock. The size and velocity distributions of the family members provide important constraints for testing our understanding of the break-up process, but erosion and dynamical diffusion of the orbits over time can erase the original signature of the collision. The recently identified young Karin family provides a unique opportunity to study a collisional outcome almost unaffected by orbit evolution. Here we report numerical simulations modelling classes of collisions that reproduce the main characteristics of the Karin family. The sensitivity of the outcome of the collision to the internal structure of the parent body allows us to show that the family must have originated from the break-up of a pre-fragmented parent body, and that all large family members formed by the gravitational reaccumulation of smaller bodies. We argue that most of the identified asteroid families are likely to have had a similar history.
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Affiliation(s)
- Patrick Michel
- Observatoire de la Côte d'Azur, BP 4229, 06304 Nice cedex 4, France.
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Abstract
Studies of asteroid families--groups of asteroids that formed from the fragmentation of larger bodies--are of broad interest to solar system researchers because they can provide insights into collisional processes, as well as the interior structures, strengths, and compositions of asteroids. It is generally accepted that members of the Koronis family were created by collisional disruption of a homogeneous parent body and therefore share the same formation age and subsequent collisional history. The temporal variations in observed brightness of the Koronis family members (a consequence of their rotation) are, however, larger than expected. Preferential alignment of spin vectors had been proposed as a possible explanation, but recent modelling predicted that family formation yields random spin vectors among the resulting fragments. Both hypotheses have been untested by observations. Here I show that the actual distribution of spin vectors among the largest members of the Koronis family falls within markedly nonrandom 'spin clusters'. Reconciling models of family formation and evolution with the unexpected alignments of spin obliquity and correlations with spin rates presents a new challenge in understanding asteroid collisional processes.
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Affiliation(s)
- Stephen M Slivan
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Rm 54-410, Cambridge, Massachusetts 02139, USA.
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25
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Affiliation(s)
- Joseph A Burns
- Department of Theoretical and Applied Mechanics and Department of Astronomy, Cornell University, Ithaca, NY 14853, USA.
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Nesvorný D, Bottke WF, Dones L, Levison HF. The recent breakup of an asteroid in the main-belt region. Nature 2002; 417:720-71. [PMID: 12066178 DOI: 10.1038/nature00789] [Citation(s) in RCA: 206] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The present population of asteroids in the main belt is largely the result of many past collisions. Ideally, the asteroid fragments resulting from each impact event could help us understand the large-scale collisions that shaped the planets during early epochs. Most known asteroid fragment families, however, are very old and have therefore undergone significant collisional and dynamical evolution since their formation. This evolution has masked the properties of the original collisions. Here we report the discovery of a family of asteroids that formed in a disruption event only 5.8 +/- 0.2 million years ago, and which has subsequently undergone little dynamical and collisional evolution. We identified 39 fragments, two of which are large and comparable in size (diameters of approximately 19 and approximately 14 km), with the remainder exhibiting a continuum of sizes in the range 2-7 km. The low measured ejection velocities suggest that gravitational re-accumulation after a collision may be a common feature of asteroid evolution. Moreover, these data can be used to check numerical models of larger-scale collisions.
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Affiliation(s)
- David Nesvorný
- Southwest Research Institute, 1050 Walnut St, Suite 426, Boulder, Colorado 80302, USA.
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Bottke WF, Vokrouhlický D, Broz M, Nesvorný D, Morbidelli A. Dynamical spreading of asteroid families by the Yarkovsky effect. Science 2001; 294:1693-6. [PMID: 11721049 DOI: 10.1126/science.1066760] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The orbital distributions of prominent asteroid families are thought to be direct by-products of catastrophic disruption events among diameter D greater, similar 100 kilometer bodies. Ejection velocities derived from studying observed families, however, are surprisingly high compared with results from impact experiments and simulations. One way to resolve this apparent contradiction is by assuming that D less, similar 20 kilometer family members, since their formation, have undergone semimajor axis drift by the thermal force called the Yarkovsky effect. Interactions between drifting family members and resonances can also produce unique eccentricity and/or inclination changes. Together, these outcomes help explain (i) why families are sharply bounded by nearby Kirkwood gaps, (ii) why some families have asymmetric shapes, and (iii) the curious presence of family members on short-lived orbits.
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Affiliation(s)
- W F Bottke
- Southwest Research Institute, 1050 Walnut Street, Suite 426, Boulder, CO 80302, USA.
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