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Geologic History and Crater Morphology of Asteroid (162173) Ryugu

Cho, Yuichiro and Morota, Tomokatsu and Kanamaru, Masanori and Takaki, N. and Yumoto, Koki and Ernst, Carolyn M. and Hirabayashi, M. and Barnouin, Olivier S. and Tatsumi, Eri and Otto, Katharina A. and Schmitz, Nicole and Wagner, Roland and Jaumann, R. and Miyamoto, Hideaki and Kikuchi, Hiroshi and Hemmi, Ryodo and Honda, R. and Kameda, Shingo and Yokota, Y. and Kouyama, T. and Suzuki, Hidehiko and Yamada, Manabu and Sakatani, Naoya and Honda, Chikatoshi and Hayakawa, Masahiro and Yoshioka, Kazuo and Matsuoka, Moe and Michikami, Tatsuhiro and Hirata, Naru and Hirotaka, Sawada and Ogawa, Kazunori and Sugita, Seiji (2021) Geologic History and Crater Morphology of Asteroid (162173) Ryugu. JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS, 126 (8), e2020JE006572. Wiley. doi: 10.1029/2020JE006572. ISSN 2169-9097.

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Official URL: https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JE006572

Abstract

Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high-resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant boulders on and under the surface of the rubble-pile asteroid affect crater morphology. Most of the craters on Ryugu exhibit well-defined circular depressions, unlike those observed on asteroid Itokawa. The craters are typically outlined by boulders remaining on the rim. Large craters (diameter > 100 m) host abundant and sometimes unproportionally large boulders on their floors. Small craters (<20 m) are characterized by smooth circular floors distinguishable from the boulder-rich exterior. Such small craters tend to have dark centers of unclear origin. The correlation between crater size and boulder number density suggests that some processes sort the size of boulders in the shallow (<30 m) subsurface. Furthermore, the crater size-frequency distributions (CSFDs) of different regions on Ryugu record multiple geologic events, revealing the diverse geologic history on this 1-km asteroid. Our crater-counting analyses indicate that the equatorial ridge is the oldest structure of Ryugu and was formed 23–30 Myr ago. Then, Ryugu was partially resurfaced, possibly by the impact that formed the Urashima crater 5–12 Myr ago. Subsequently, a large-scale resurfacing event formed the western bulge and the fossae 2–9 Myr ago. Following this process, the spin of Ryugu slowed down plausibly due to the YORP effect. The transition of isochrons in a CSFD suggests that Ryugu was decoupled from the main belt and transferred to a near-Earth orbit 0.2–7 Myr ago.

Item URL in elib:https://elib.dlr.de/147993/
Document Type:Article
Additional Information:Preprint verfügbar in Earth and Space Science Open Archive, https://doi.org/10.1002/essoar.10506689.2
Title:Geologic History and Crater Morphology of Asteroid (162173) Ryugu
Authors:
AuthorsInstitution or Email of AuthorsAuthor's ORCID iD
Cho, YuichiroThe University of Tokyo, Department of Earth and Planetary Sciencehttps://orcid.org/0000-0003-2749-2204
Morota, TomokatsuThe University of TokyoUNSPECIFIED
Kanamaru, MasanoriOsaka Universityhttps://orcid.org/0000-0002-2533-3077
Takaki, N.The University of Tokyo, Tokyo 113-0033, JapanUNSPECIFIED
Yumoto, KokiThe University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, JapanUNSPECIFIED
Ernst, Carolyn M.Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USAUNSPECIFIED
Hirabayashi, M.Auburn University, Auburn, AL 36849, USAUNSPECIFIED
Barnouin, Olivier S.Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USAUNSPECIFIED
Tatsumi, EriDep. of Earth and Planetary Science, univ. of TokyoUNSPECIFIED
Otto, Katharina A.Katharina.Otto (at) dlr.dehttps://orcid.org/0000-0002-0675-1177
Schmitz, NicoleNicole.Schmitz (at) dlr.dehttps://orcid.org/0000-0001-6481-6189
Wagner, RolandRoland.Wagner (at) dlr.deUNSPECIFIED
Jaumann, R.FU BerlinUNSPECIFIED
Miyamoto, HideakiDept. Systems I nnovation, Univ ersity of Tokyo, Tokyo 113-8656, JapanUNSPECIFIED
Kikuchi, Hiroshikikuchi.hiroshi (at) jaxa.jpUNSPECIFIED
Hemmi, Ryodohemmi (at) seed.um.u-tokyo.ac.jpUNSPECIFIED
Honda, R.Kochi University, JapanUNSPECIFIED
Kameda, ShingoRikkyo University, Tokyo 171-8501, JapanUNSPECIFIED
Yokota, Y.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS / JAXA) 3-1-1 Yoshinodai, Chuo-Ku, Sagamihara 252-5210, JapanUNSPECIFIED
Kouyama, T.National Institute of Advanced Industrial Science and Technology, Tokyo, Japanhttps://orcid.org/0000-0002-1060-3986
Suzuki, HidehikoMeiji University, Kawasaki, 214-8571, JapanUNSPECIFIED
Yamada, ManabuPERC, Narashino, JapanUNSPECIFIED
Sakatani, NaoyaInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, JapanUNSPECIFIED
Honda, ChikatoshiUniv Aizu, Res Ctr Adv Informat Sci & Technol, Aizu Wakamatsu, Fukushima, JapanUNSPECIFIED
Hayakawa, MasahiroInstitute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, JapanUNSPECIFIED
Yoshioka, KazuoThe University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, JapanUNSPECIFIED
Matsuoka, MoeInstitute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency, Sagamihara, JapanUNSPECIFIED
Michikami, Tatsuhiromichikami (at) hiro.kindai.ac.jpUNSPECIFIED
Hirata, Naruisas/jaxa japanUNSPECIFIED
Hirotaka, SawadaJaxaUNSPECIFIED
Ogawa, Kazunorikazunori.ogawa (at) topaz.kobe-u.ac.jpUNSPECIFIED
Sugita, SeijiUniversity of Tokyo, Tokyo, JapanUNSPECIFIED
Date:12 July 2021
Journal or Publication Title:JOURNAL OF GEOPHYSICAL RESEARCH-PLANETS
Refereed publication:Yes
Open Access:No
Gold Open Access:No
In SCOPUS:Yes
In ISI Web of Science:Yes
Volume:126
DOI :10.1029/2020JE006572
Page Range:e2020JE006572
Publisher:Wiley
ISSN:2169-9097
Status:Published
Keywords:Crater, Morphology, Asteroid, Ryugu, Hayabusa-2
HGF - Research field:Aeronautics, Space and Transport
HGF - Program:Space
HGF - Program Themes:Space Exploration
DLR - Research area:Raumfahrt
DLR - Program:R EW - Space Exploration
DLR - Research theme (Project):R - Project MASCOT - Science
Location: Berlin-Adlershof
Institutes and Institutions:Institute of Planetary Research > Planetary Geology
Deposited By: Schmitz, Nicole
Deposited On:06 Jan 2022 08:31
Last Modified:06 Jan 2022 08:31

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