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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


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
AuthorsInstitution or Email of AuthorsAuthor's ORCID iDORCID Put Code
Cho, YuichiroThe University of Tokyo, Department of Earth and Planetary Sciencehttps://orcid.org/0000-0003-2749-2204UNSPECIFIED
Morota, TomokatsuThe University of TokyoUNSPECIFIEDUNSPECIFIED
Kanamaru, MasanoriOsaka Universityhttps://orcid.org/0000-0002-2533-3077UNSPECIFIED
Takaki, N.The University of Tokyo, Tokyo 113-0033, JapanUNSPECIFIEDUNSPECIFIED
Yumoto, KokiThe University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, JapanUNSPECIFIEDUNSPECIFIED
Ernst, Carolyn M.Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USAUNSPECIFIEDUNSPECIFIED
Hirabayashi, M.Auburn University, Auburn, AL 36849, USAUNSPECIFIEDUNSPECIFIED
Barnouin, Olivier S.Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USAUNSPECIFIEDUNSPECIFIED
Tatsumi, EriDep. of Earth and Planetary Science, univ. of TokyoUNSPECIFIEDUNSPECIFIED
Otto, Katharina A.UNSPECIFIEDhttps://orcid.org/0000-0002-0675-1177UNSPECIFIED
Schmitz, NicoleUNSPECIFIEDhttps://orcid.org/0000-0001-6481-6189UNSPECIFIED
Miyamoto, HideakiDept. Systems I nnovation, Univ ersity of Tokyo, Tokyo 113-8656, JapanUNSPECIFIEDUNSPECIFIED
Honda, R.Kochi University, JapanUNSPECIFIEDUNSPECIFIED
Kameda, ShingoRikkyo University, Tokyo 171-8501, JapanUNSPECIFIEDUNSPECIFIED
Yokota, Y.Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS / JAXA) 3-1-1 Yoshinodai, Chuo-Ku, Sagamihara 252-5210, JapanUNSPECIFIEDUNSPECIFIED
Kouyama, T.National Institute of Advanced Industrial Science and Technology, Tokyo, Japanhttps://orcid.org/0000-0002-1060-3986UNSPECIFIED
Suzuki, HidehikoMeiji University, Kawasaki, 214-8571, JapanUNSPECIFIEDUNSPECIFIED
Sakatani, NaoyaInstitute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, JapanUNSPECIFIEDUNSPECIFIED
Honda, ChikatoshiUniv Aizu, Res Ctr Adv Informat Sci & Technol, Aizu Wakamatsu, Fukushima, JapanUNSPECIFIEDUNSPECIFIED
Hayakawa, MasahiroInstitute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara, 252-5210, JapanUNSPECIFIEDUNSPECIFIED
Yoshioka, KazuoThe University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-0033, JapanUNSPECIFIEDUNSPECIFIED
Matsuoka, MoeInstitute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency, Sagamihara, JapanUNSPECIFIEDUNSPECIFIED
Hirata, Naruisas/jaxa japanUNSPECIFIEDUNSPECIFIED
Sugita, SeijiUniversity of Tokyo, Tokyo, JapanUNSPECIFIEDUNSPECIFIED
Date:12 July 2021
Journal or Publication Title:Journal of Geophysical Research: Planets
Refereed publication:Yes
Open Access:Yes
Gold Open Access:No
In ISI Web of Science:Yes
Page Range:e2020JE006572
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:27 Oct 2023 14:20

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