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Nagaashi Y, Nakamura AM. High mobility of asteroid particles revealed by measured cohesive force of meteorite fragments. SCIENCE ADVANCES 2023; 9:eadd3530. [PMID: 36930712 PMCID: PMC10022890 DOI: 10.1126/sciadv.add3530] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 02/10/2023] [Indexed: 06/18/2023]
Abstract
The cohesive force of asteroid particles is a crucial parameter in microgravity. The cohesive force was evaluated under the assumptions of lunar regolith and proportionality to particle size; however, it is sensitive to particle shape. In this study, cohesive-force measurements of meteorite fragments and aggregates consisting of silica microspheres revealed that the cohesive force is independent of the sizes of the fragments and aggregates as well as of the fragment preparation methods. The cohesive forces of the asteroid particles were found to be orders of magnitude smaller than previously predicted, explaining the high mobility of asteroid surface particles identified by space exploration.
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Williams J, Pathare AV, Costello ES, Gallinger CL, Hayne PO, Ghent RR, Paige DA, Siegler MA, Russell PS, Elder CM. The Effects of Terrain Properties Upon the Small Crater Population Distribution at Giordano Bruno: Implications for Lunar Chronology. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2022; 127:e2021JE007131. [PMID: 35865504 PMCID: PMC9287037 DOI: 10.1029/2021je007131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 04/09/2022] [Accepted: 04/12/2022] [Indexed: 06/15/2023]
Abstract
The distribution of impact craters on the ejecta of Giordano Bruno, a recent (<10 Ma) 22-km diameter crater within the lunar highlands, exhibits substantial variations. We surveyed craters D ≥ 10 m across a 1,323 km2 area of Giordano Bruno's ejecta and compared the distribution of craters with variations in thermophysical properties derived from the Lunar Reconnaissance Orbiter Diviner instrument. We used Diviner-derived rock abundance and nighttime regolith temperatures along with thermal model-predicted surface temperatures for a diversity of terrains to identify and isolate areas of the ejecta based on thermophysical properties such as bulk density and thermal conductivity. We found that thermophysical properties of the ejecta vary considerably both laterally and vertically, and consistently differ from typical regolith, indicating the presence of higher thermal inertia materials. Crater-size frequencies are significantly lower in areas with terrain properties exhibiting higher: rock abundance, nighttime temperatures, and/or modeled thermal inertia. This discrepancy in crater distribution increases for craters smaller than ∼25 m. These thermophysical variations indicate changes in the mechanical properties of the target materials. We suggest that these variations-specifically, terrain-dependent crater scaling variations and impactor-scale heterogeneities in material properties such as the presence or absence of large boulders-may influence crater diameters or inhibit crater production altogether in Giordano Bruno's ejecta; furthermore, these factors are size-dependent.
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Affiliation(s)
- J.‐P. Williams
- Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | | | - E. S. Costello
- Department of Geology and GeophysicsUniversity of Hawai'i at MānoaHonoluluHIUSA
- Hawaii Institute of Geophysics and PlanetologyHonoluluHIUSA
| | - C. L. Gallinger
- Department of Earth SciencesUniversity of Western OntarioLondonONCanada
| | - P. O. Hayne
- Astrophysical and Planetary SciencesUniversity of Colorado BoulderBoulderCOUSA
- Laboratory for Atmospheric and Space PhysicsUniversity of Colorado BoulderBoulderCOUSA
| | | | - D. A. Paige
- Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - M. A. Siegler
- Planetary Science InstituteTucsonAZUSA
- Department of Earth SciencesSouthern Methodist UniversityDallasTXUSA
| | - P. S. Russell
- Earth, Planetary and Space SciencesUniversity of CaliforniaLos AngelesCAUSA
| | - C. M. Elder
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
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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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Cambioni S, Delbo M, Poggiali G, Avdellidou C, Ryan AJ, Deshapriya JDP, Asphaug E, Ballouz RL, Barucci MA, Bennett CA, Bottke WF, Brucato JR, Burke KN, Cloutis E, DellaGiustina DN, Emery JP, Rozitis B, Walsh KJ, Lauretta DS. Fine-regolith production on asteroids controlled by rock porosity. Nature 2021; 598:49-52. [PMID: 34616055 DOI: 10.1038/s41586-021-03816-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 07/08/2021] [Indexed: 11/09/2022]
Abstract
Spacecraft missions have observed regolith blankets of unconsolidated subcentimetre particles on stony asteroids1-3. Telescopic data have suggested the presence of regolith blankets also on carbonaceous asteroids, including (101955) Bennu4 and (162173) Ryugu5. However, despite observations of processes that are capable of comminuting boulders into unconsolidated materials, such as meteoroid bombardment6,7 and thermal cracking8, Bennu and Ryugu lack extensive areas covered in subcentimetre particles7,9. Here we report an inverse correlation between the local abundance of subcentimetre particles and the porosity of rocks on Bennu. We interpret this finding to mean that accumulation of unconsolidated subcentimetre particles is frustrated where the rocks are highly porous, which appears to be most of the surface10. The highly porous rocks are compressed rather than fragmented by meteoroid impacts, consistent with laboratory experiments11,12, and thermal cracking proceeds more slowly than in denser rocks. We infer that regolith blankets are uncommon on carbonaceous asteroids, which are the most numerous type of asteroid13. By contrast, these terrains should be common on stony asteroids, which have less porous rocks and are the second-most populous group by composition13. The higher porosity of carbonaceous asteroid materials may have aided in their compaction and cementation to form breccias, which dominate the carbonaceous chondrite meteorites14.
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Affiliation(s)
- S Cambioni
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA. .,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
| | - M Delbo
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - G Poggiali
- INAF - Osservatorio Astrofisico di Arcetri, Florence, Italy
| | - C Avdellidou
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - A J Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J D P Deshapriya
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France
| | - E Asphaug
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M A Barucci
- LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - J R Brucato
- INAF - Osservatorio Astrofisico di Arcetri, Florence, Italy
| | - K N Burke
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E Cloutis
- Department of Geography, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J P Emery
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
| | - B Rozitis
- School of Physical Sciences, The Open University, Milton Keynes, UK
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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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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Velbel MA, Zolensky ME. Thermal metamorphism of CM chondrites: A dehydroxylation-based peak-temperature thermometer and implications for sample return from asteroids Ryugu and Bennu. METEORITICS & PLANETARY SCIENCE 2021; 56:546-585. [PMID: 34262245 PMCID: PMC8252763 DOI: 10.1111/maps.13636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 01/17/2021] [Indexed: 06/13/2023]
Abstract
The target bodies of C-complex asteroid sample return missions are carbonaceous chondrite-like near-Earth asteroids (NEAs), chosen for the abundance and scientific importance of their organic compounds and "hydrous" (including hydroxylated) minerals, such as serpentine-group phyllosilicates. Science objectives include returning samples of pristine carbonaceous regolith from asteroids for study of the nature, history, and distribution of its constituent minerals, organic material, and other volatiles. Heating after the natural aqueous alteration that formed the abundant phyllosilicates in CM and similar carbonaceous chondrites dehydroxylated them and altered or decomposed other volumetrically minor constituents (e.g., carbonates, sulfides, organic molecules; Tonui et al. 2003, 2014). We propose a peak-temperature thermometer based on dehydroxylation as measured by analytical totals from electron probe microanalysis (EPMA) of matrices in a number of heated and aqueously altered (but not further heated) CM chondrites. Some CM lithologies in Maribo and Sutter's Mill do not exhibit the matrix dehydroxylation expected for surface temperatures expected from insolation of meteoroids with their known orbital perihelia. This suggests that insolated-heated meteoroid surfaces were lost by ablation during passage through Earth's atmosphere, and that insolation-heated material is more likely to be encountered among returned asteroid regolith samples than in meteorites. More generally, several published lines of evidence suggest that episodic heating of some CM material, most likely by impacts, continued intermittently and locally up to billions of years after assembly and early heating of ancestral CM chondrite bodies. Mission spectroscopic measures of hydration can be used to estimate the extent of dehydroxylation, and the new dehydroxylation thermometer can be used directly to select fragments of returned samples most likely to contain less thermally altered inventories of primitive organic molecules.
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Affiliation(s)
- Michael A. Velbel
- Department of Earth and Environmental SciencesMichigan State University288 Farm Lane, Room 207, Natural Sciences BuildingEast LansingMichigan48824–1115USA
- Division of MeteoritesDepartment of Mineral SciencesNational Museum of Natural HistorySmithsonian InstitutionWashingtonDistrict of Columbia20013–7012USA
| | - Michael E. Zolensky
- X12 Astromaterials Research and Exploration ScienceNASA Johnson Space CenterHoustonTexas77058USA
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7
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Abstract
The Martian satellites Phobos and Deimos hold many unanswered questions that may provide clues to the origin of Mars. These moons are low Δv stopover sites to Mars. Some human missions to Mars typically identify Phobos and Deimos as staging bases for Mars surface exploration. Astronauts could base initial operations there in lieu of repeated voyages to and from the planet surface, to refuel transiting spacecraft, to teleoperate robotics and other critical machinery, and to develop habitable infrastructure ahead of human landings. Despite their strategic and scientific significance, there has been no successful dedicated mission to either moon. For this reason, we propose Perseus, a geological imaging CubeSat mission to Phobos. Perseus, a 27U, 54kg CubeSat will return thermal and visible images at resolutions better than currently available over most of Phobos’ surface. This includes visible images at 5m/pixel and thermal images at 25m/pixel of Phobos’ surface. The Perseus mission is nominally intended to be a co-orbital mission, where the spacecraft will encounter Phobos on its Martian orbit. However, a hyperbolic rendezvous mission concept, to image Phobos on a hyperbolic flyby, is also considered to reduce the risks associated with orbit capture and to reduce mission costs. This paper presents the preliminary feasibility, science objectives, and technological development challenges of achieving these science goals. We then formulate two rendezvous concepts as a series of three nonlinear optimization problems that span the design tree of mission concepts. The tree’s root node is the heliocentric cruise problem, which identifies the near-optimal launch and arrival windows for the Perseus spacecraft. The leaf nodes of the design tree are the two rendezvous concepts that identify near-optimal co-orbital and hyperbolic trajectories for Phobos’ reconnaissance. The design problems are solved using evolutionary algorithms, and the performance of the selected mission concepts is then examined. The results indicate that a co-orbital encounter allows about one encounter per day with about 6 min per encounter. The hyperbolic encounter, on the other hand, allows a single encounter where the spacecraft will spend about 2 min in the imaging region with respect to Phobos. The spacecraft will obtain higher resolution images of Phobos on this feasible region than have ever been seen for most of the surface. These detailed images will help identify candidate landing sites and provide critical data to derisk future surface missions to Phobos.
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8
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Hörz F, Basilevsky AT, Head JW, Cintala MJ. Erosion of lunar surface rocks by impact processes: A synthesis. PLANETARY AND SPACE SCIENCE 2020; 194:105105. [PMID: 33012847 PMCID: PMC7518182 DOI: 10.1016/j.pss.2020.105105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 09/11/2020] [Accepted: 09/18/2020] [Indexed: 06/11/2023]
Abstract
This report summarizes observations of returned Apollo rocks and soils, lunar surface images, orbital observations, and experimental impacts related to the erosion and comminution of rocks exposed at the lunar surface. The objective is to develop rigorous criteria for the recognition of impact processes that assist in distinguishing "impact" from other potential erosional processes, particularly thermal fatigue, which has recently been advocated specifically for asteroids. Impact in rock is a process that is centrally to bilaterally symmetric, resulting in highly crushed, high-albedo, quasicircular depressions surrounded by volumetrically prominent spall zones. Containing central glass-lined pits in many cases, such features provide distinctive evidence of impact that is not duplicated by any other process. Additional evidence of impact can include radial fracture systems in the target that emanate from the impact point and clusters of fragments that attest to the lateral acceleration and displacement of each one. It is also important to note that impact produces a wide variety of fragment shapes that might totally overlap with those produced by thermal fatigue; we consider fragment shape to be an unreliable criterion for either process. The stochastic nature of the impact process will result in exponential survival times of surface rocks; that is, rock destruction initially is relatively efficient, but it is followed by ever increasing surface times for the last rock remnants. Thermal fatigue, however, is essentially a thermal-equilibrium process. The corresponding distribution of survival times should be much more peaked in comparison, presumably Gaussian, and diagnostically different from that due to impact. Given the abundance of evidence that has been gleaned from returned Apollo rocks and soils, it is surprising how little has been learned about the impact process from the photography of rocks and boulders taken by the astronauts on the lunar surface. This suggests that it will require rocks and soils returned from asteroids to evaluate the relative roles of thermal versus impact-triggered rock erosion, particularly when both processes are likely to be operating.
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Affiliation(s)
- Friedrich Hörz
- Jacobs-JETS, 2224 Bay Area Boulevard, Houston, TX, 77058, USA
| | - Alexander T Basilevsky
- Vernadsky Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow, 1199991, Russia
| | - James W Head
- Department of Geological Sciences, Brown University, Providence, RI, 02912, USA
| | - Mark J Cintala
- Code XI3, NASA Johnson Space Center, 2101 NASA Parkway, Houston, TX, 77058, USA
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9
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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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10
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Rozitis B, Ryan AJ, Emery JP, Christensen PR, Hamilton VE, Simon AA, Reuter DC, Al Asad M, Ballouz RL, Bandfield JL, Barnouin OS, Bennett CA, Bernacki M, Burke KN, Cambioni S, Clark BE, Daly MG, Delbo M, DellaGiustina DN, Elder CM, Hanna RD, Haberle CW, Howell ES, Golish DR, Jawin ER, Kaplan HH, Lim LF, Molaro JL, Munoz DP, Nolan MC, Rizk B, Siegler MA, Susorney HCM, Walsh KJ, Lauretta DS. Asteroid (101955) Bennu's weak boulders and thermally anomalous equator. SCIENCE ADVANCES 2020; 6:eabc3699. [PMID: 33033037 PMCID: PMC7544501 DOI: 10.1126/sciadv.abc3699] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 09/09/2020] [Indexed: 05/18/2023]
Abstract
Thermal inertia and surface roughness are proxies for the physical characteristics of planetary surfaces. Global maps of these two properties distinguish the boulder population on near-Earth asteroid (NEA) (101955) Bennu into two types that differ in strength, and both have lower thermal inertia than expected for boulders and meteorites. Neither has strongly temperature-dependent thermal properties. The weaker boulder type probably would not survive atmospheric entry and thus may not be represented in the meteorite collection. The maps also show a high-thermal inertia band at Bennu's equator, which might be explained by processes such as compaction or strength sorting during mass movement, but these explanations are not wholly consistent with other data. Our findings imply that other C-complex NEAs likely have boulders similar to those on Bennu rather than finer-particulate regoliths. A tentative correlation between albedo and thermal inertia of C-complex NEAs may be due to relative abundances of boulder types.
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Affiliation(s)
- B Rozitis
- School of Physical Sciences, The Open University, Milton Keynes, UK.
| | - A J Ryan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - J P Emery
- Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA
| | - P R Christensen
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | | | - A A Simon
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - D C Reuter
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - M Al Asad
- Department of Earth, Atmospheric, and Ocean Science, University of British Columbia, Vancouver, BC, Canada
| | - 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
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M Bernacki
- Mines ParisTech, PSL Research University, CEMEF-Centre de mise en forme des matériaux, Sophia Antipolis Cedex, France
| | - K N Burke
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - S Cambioni
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - M Delbo
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C M Elder
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - R D Hanna
- Jackson School of Geosciences, University of Texas, Austin, TX, USA
| | - C W Haberle
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - H H Kaplan
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - L F Lim
- NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
| | - J L Molaro
- Planetary Science Institute, Tucson, AZ, USA
| | - D Pino Munoz
- Mines ParisTech, PSL Research University, CEMEF-Centre de mise en forme des matériaux, Sophia Antipolis Cedex, France
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M A Siegler
- Planetary Science Institute, Tucson, AZ, USA
| | - H C M Susorney
- School of Earth Sciences, University of Bristol, Bristol, UK
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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11
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Bottke WF, Moorhead AV, Connolly HC, Hergenrother CW, Molaro JL, Michel P, Nolan MC, Schwartz SR, Vokrouhlický D, Walsh KJ, Lauretta DS. Meteoroid Impacts as a Source of Bennu's Particle Ejection Events. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2020; 125:e2019JE006282. [PMID: 32999798 PMCID: PMC7507787 DOI: 10.1029/2019je006282] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 02/07/2020] [Accepted: 04/23/2020] [Indexed: 06/11/2023]
Abstract
Asteroid (101955) Bennu, a near-Earth object with a primitive carbonaceous chondrite-like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter-family comets and have evolved toward the Sun by Poynting-Robertson drag. We find that 7,000-J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations.
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Affiliation(s)
| | - A. V. Moorhead
- NASA Meteoroid Environment Office, Marshall Space Flight Center EV44HuntsvilleALUSA
| | - H. C. Connolly
- Department of GeologyRowan UniversityGlassboroNJUSA
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | | | | | - P. Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire LagrangeNiceFrance
| | - M. C. Nolan
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - S. R. Schwartz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - D. Vokrouhlický
- Institute of AstronomyCharles UniversityPragueCzech Republic
| | | | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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12
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Molaro JL, Hergenrother CW, Chesley SR, Walsh KJ, Hanna RD, Haberle CW, Schwartz SR, Ballouz R, Bottke WF, Campins HJ, Lauretta DS. Thermal Fatigue as a Driving Mechanism for Activity on Asteroid Bennu. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2020; 125:e2019JE006325. [PMID: 32999800 PMCID: PMC7507781 DOI: 10.1029/2019je006325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 07/15/2020] [Accepted: 07/18/2020] [Indexed: 06/11/2023]
Abstract
Many boulders on (101955) Bennu, a near-Earth rubble pile asteroid, show signs of in situ disaggregation and exfoliation, indicating that thermal fatigue plays an important role in its landscape evolution. Observations of particle ejections from its surface also show it to be an active asteroid, though the driving mechanism of these events is yet to be determined. Exfoliation has been shown to mobilize disaggregated particles in terrestrial environments, suggesting that it may be capable of ejecting material from Bennu's surface. We investigate the nature of thermal fatigue on the asteroid, and the efficacy of fatigue-driven exfoliation as a mechanism for generating asteroid activity, by performing finite element modeling of stress fields induced in boulders from diurnal cycling. We develop a model to predict the spacing of exfoliation fractures and the number and speed of particles that may be ejected during exfoliation events. We find that crack spacing ranges from ~1 mm to 10 cm and disaggregated particles have ejection speeds up to ~2 m/s. Exfoliation events are most likely to occur in the late afternoon. These predictions are consistent with observed ejection events at Bennu and indicate that thermal fatigue is a viable mechanism for driving asteroid activity. Crack propagation rates and ejection speeds are greatest at perihelion when the diurnal temperature variation is largest, suggesting that events should be more energetic and more frequent when closer to the Sun. Annual thermal stresses that arise in large boulders may influence the spacing of exfoliation cracks or frequency of ejection events.
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Affiliation(s)
| | | | - S. R. Chesley
- Jet Propulsion LaboratoryCalifornia Institute of TechnologyPasadenaCAUSA
| | | | - R. D. Hanna
- Jackson School of GeosciencesUniversity of Texas at AustinAustinTXUSA
| | - C. W. Haberle
- School of Earth and Space ExplorationArizona State UniversityTempeAZUSA
| | - S. R. Schwartz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | - R.‐L. Ballouz
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
| | | | - H. J. Campins
- Department of PhysicsUniversity of Central FloridaOrlandoFLUSA
| | - D. S. Lauretta
- Lunar and Planetary LaboratoryUniversity of ArizonaTucsonAZUSA
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13
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Lauretta DS, Hergenrother CW, Chesley SR, Leonard JM, Pelgrift JY, Adam CD, Al Asad M, Antreasian PG, Ballouz RL, Becker KJ, Bennett CA, Bos BJ, Bottke WF, Brozović M, Campins H, Connolly HC, Daly MG, Davis AB, de León J, DellaGiustina DN, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Farnocchia D, Glavin DP, Golish DR, Hartzell CM, Jacobson RA, Jawin ER, Jenniskens P, Kidd JN, Lessac-Chenen EJ, Li JY, Libourel G, Licandro J, Liounis AJ, Maleszewski CK, Manzoni C, May B, McCarthy LK, McMahon JW, Michel P, Molaro JL, Moreau MC, Nelson DS, Owen WM, Rizk B, Roper HL, Rozitis B, Sahr EM, Scheeres DJ, Seabrook JA, Selznick SH, Takahashi Y, Thuillet F, Tricarico P, Vokrouhlický D, Wolner CWV. Episodes of particle ejection from the surface of the active asteroid (101955) Bennu. Science 2020; 366:366/6470/eaay3544. [PMID: 31806784 DOI: 10.1126/science.aay3544] [Citation(s) in RCA: 96] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 10/22/2019] [Indexed: 11/02/2022]
Abstract
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts.
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Affiliation(s)
- D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - S R Chesley
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | | | | | - C D Adam
- KinetX Aerospace, Simi Valley, CA, USA
| | - M Al Asad
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, BC, Canada
| | | | - R-L Ballouz
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B J Bos
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - M Brozović
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA.,Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - A B Davis
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J de León
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.,Department of Geosciences, University of Arizona, Tucson, AZ, USA
| | | | - J P Dworkin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J P Emery
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA.,Department of Astronomy and Planetary Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - D Farnocchia
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - D P Glavin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C M Hartzell
- Department of Aerospace Engineering, University of Maryland, College Park, MD, USA
| | - R A Jacobson
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - P Jenniskens
- SETI (Search for Extraterrestrial Intelligence) Institute, Mountain View, CA, USA
| | - J N Kidd
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - J-Y Li
- Planetary Science Institute, Tucson, AZ, USA
| | - G Libourel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - J Licandro
- Instituto de Astrofísica de Canarias and Departamento de Astrofísica, Universidad de La Laguna, Tenerife, Spain
| | - A J Liounis
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - C K Maleszewski
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C Manzoni
- London Stereoscopic Company, London, UK
| | - B May
- London Stereoscopic Company, London, UK
| | | | - J W McMahon
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - J L Molaro
- Planetary Science Institute, Tucson, AZ, USA
| | - M C Moreau
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | | | - W M Owen
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H L Roper
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rozitis
- School of Physical Sciences, Open University, Milton Keynes, UK
| | - E M Sahr
- KinetX Aerospace, Simi Valley, CA, USA
| | - D J Scheeres
- Smead Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J A Seabrook
- The Centre for Research in Earth and Space Science, York University, Toronto, ON, Canada
| | - S H Selznick
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - Y Takahashi
- Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
| | - F Thuillet
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS (Centre national de la recherche scientifique), Laboratoire Lagrange, Nice, France
| | - P Tricarico
- Planetary Science Institute, Tucson, AZ, USA
| | - D Vokrouhlický
- Institute of Astronomy, Charles University, Prague, Czech Republic
| | - C W V Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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14
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Elkins‐Tanton LT, Asphaug E, Bell JF, Bercovici H, Bills B, Binzel R, Bottke WF, Dibb S, Lawrence DJ, Marchi S, McCoy TJ, Oran R, Park RS, Peplowski PN, Polanskey CA, Prettyman TH, Russell CT, Schaefer L, Weiss BP, Wieczorek MA, Williams DA, Zuber MT. Observations, Meteorites, and Models: A Preflight Assessment of the Composition and Formation of (16) Psyche. JOURNAL OF GEOPHYSICAL RESEARCH. PLANETS 2020; 125:e2019JE006296. [PMID: 32714727 PMCID: PMC7375145 DOI: 10.1029/2019je006296] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/29/2020] [Accepted: 01/29/2020] [Indexed: 06/02/2023]
Abstract
Some years ago, the consensus was that asteroid (16) Psyche was almost entirely metal. New data on density, radar properties, and spectral signatures indicate that the asteroid is something perhaps even more enigmatic: a mixed metal and silicate world. Here we combine observations of Psyche with data from meteorites and models for planetesimal formation to produce the best current hypotheses for Psyche's properties and provenance. Psyche's bulk density appears to be between 3,400 and 4,100 kg m-3. Psyche is thus predicted to have between ~30 and ~60 vol% metal, with the remainder likely low-iron silicate rock and not more than ~20% porosity. Though their density is similar, mesosiderites are an unlikely analog to bulk Psyche because mesosiderites have far more iron-rich silicates than Psyche appears to have. CB chondrites match both Psyche's density and spectral properties, as can some pallasites, although typical pallasitic olivine contains too much iron to be consistent with the reflectance spectra. Final answers, as well as resolution of contradictions in the data set of Psyche physical properties, for example, the thermal inertia measurements, may not be resolved until the NASA Psyche mission arrives in orbit at the asteroid. Despite the range of compositions and formation processes for Psyche allowed by the current data, the science payload of the Psyche mission (magnetometers, multispectral imagers, neutron spectrometer, and a gamma-ray spectrometer) will produce data sets that distinguish among the models.
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Affiliation(s)
| | | | | | | | - B. Bills
- Jet Propulsion LaboratoryPasadenaCAUSA
| | - R. Binzel
- Massachusetts Institute of TechnologyCambridgeMAUSA
| | | | - S. Dibb
- Arizona State UniversityPhoenixAZUSA
| | | | - S. Marchi
- Southwest Research InstituteBoulderCOUSA
| | | | - R. Oran
- Massachusetts Institute of TechnologyCambridgeMAUSA
| | | | | | | | | | | | | | - B. P. Weiss
- Massachusetts Institute of TechnologyCambridgeMAUSA
| | - M. A. Wieczorek
- Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Université Côte d'AzurNiceFrance
| | | | - M. T. Zuber
- Massachusetts Institute of TechnologyCambridgeMAUSA
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15
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Jaumann R, Schmitz N, Ho TM, Schröder SE, Otto KA, Stephan K, Elgner S, Krohn K, Preusker F, Scholten F, Biele J, Ulamec S, Krause C, Sugita S, Matz KD, Roatsch T, Parekh R, Mottola S, Grott M, Michel P, Trauthan F, Koncz A, Michaelis H, Lange C, Grundmann JT, Maibaum M, Sasaki K, Wolff F, Reill J, Moussi-Soffys A, Lorda L, Neumann W, Vincent JB, Wagner R, Bibring JP, Kameda S, Yano H, Watanabe S, Yoshikawa M, Tsuda Y, Okada T, Yoshimitsu T, Mimasu Y, Saiki T, Yabuta H, Rauer H, Honda R, Morota T, Yokota Y, Kouyama T. Images from the surface of asteroid Ryugu show rocks similar to carbonaceous chondrite meteorites. Science 2020; 365:817-820. [PMID: 31439797 DOI: 10.1126/science.aaw8627] [Citation(s) in RCA: 80] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 07/23/2019] [Indexed: 11/02/2022]
Abstract
The near-Earth asteroid (162173) Ryugu is a 900-m-diameter dark object expected to contain primordial material from the solar nebula. The Mobile Asteroid Surface Scout (MASCOT) landed on Ryugu's surface on 3 October 2018. We present images from the MASCOT camera (MASCam) taken during the descent and while on the surface. The surface is covered by decimeter- to meter-sized rocks, with no deposits of fine-grained material. Rocks appear either bright, with smooth faces and sharp edges, or dark, with a cauliflower-like, crumbly surface. Close-up images of a rock of the latter type reveal a dark matrix with small, bright, spectrally different inclusions, implying that it did not experience extensive aqueous alteration. The inclusions appear similar to those in carbonaceous chondrite meteorites.
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Affiliation(s)
- R Jaumann
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany. .,Free University of Berlin, Institute of Geosciences, Berlin, Germany
| | - N Schmitz
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - T-M Ho
- DLR, Institute of Space Systems, Bremen, Germany
| | - S E Schröder
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - K A Otto
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - K Stephan
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - S Elgner
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - K Krohn
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - F Preusker
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - F Scholten
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - J Biele
- DLR, Microgravity User Support Center, Linder Höhe, Cologne, Germany
| | - S Ulamec
- DLR, Microgravity User Support Center, Linder Höhe, Cologne, Germany
| | - C Krause
- DLR, Microgravity User Support Center, Linder Höhe, Cologne, Germany
| | - S Sugita
- Department of Earth and Planetary Science, School of Science, University of Tokyo, Tokyo 113-0033, Japan
| | - K-D Matz
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - T Roatsch
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - R Parekh
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany.,Free University of Berlin, Institute of Geosciences, Berlin, Germany
| | - S Mottola
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - M Grott
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de la Recherche Scientifique, Laboratoire Lagrange, Nice, France
| | - F Trauthan
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - A Koncz
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - H Michaelis
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - C Lange
- DLR, Institute of Space Systems, Bremen, Germany
| | | | - M Maibaum
- DLR, Microgravity User Support Center, Linder Höhe, Cologne, Germany
| | - K Sasaki
- DLR, Institute of Space Systems, Bremen, Germany
| | - F Wolff
- DLR, Institute of System Dynamics and Control, Oberpfaffenhofen, Germany
| | - J Reill
- DLR, Institute of Robotics and Mechatronics, Oberpfaffenhofen, Germany
| | - A Moussi-Soffys
- Centre National d'Études Spatiales, 18 Avenue E. Belin, Toulouse 31401, France
| | - L Lorda
- Centre National d'Études Spatiales, 18 Avenue E. Belin, Toulouse 31401, France
| | - W Neumann
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - J-B Vincent
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - R Wagner
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany
| | - J-P Bibring
- L'Université de Paris Sud-Orsay, Institut d'Astrophysique Spatiale, Orsay, France
| | - S Kameda
- Department of Physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501, Japan
| | - H Yano
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - S Watanabe
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan.,Department of Earth and Planetary Sciences, Nagoya University Furo-cho Chikusa-ku, Nagoya, Japan
| | - M Yoshikawa
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Y Tsuda
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - T Okada
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - T Yoshimitsu
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - Y Mimasu
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - T Saiki
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - H Yabuta
- Department of Earth and Planetary Systems Science, Hiroshima University, Hiroshima, Japan
| | - H Rauer
- German Aerospace Center (DLR), Institute of Planetary Research, Berlin, Germany.,Free University of Berlin, Institute of Geosciences, Berlin, Germany
| | - R Honda
- Kochi University, Department of Information Science, Akebono, Kochi, Japan
| | - T Morota
- University of Tokyo, Department of Earth and Planetary Science, Hongo, Bunkyo, Tokyo, Japan
| | - Y Yokota
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, Sagamihara, Japan
| | - T Kouyama
- National Institute of Advanced Industrial Science and Technology, Aomi, Koto, Tokyo, Japan
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16
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Libourel G, Nakamura AM, Beck P, Potin S, Ganino C, Jacomet S, Ogawa R, Hasegawa S, Michel P. Hypervelocity impacts as a source of deceiving surface signatures on iron-rich asteroids. SCIENCE ADVANCES 2019; 5:eaav3971. [PMID: 31489363 PMCID: PMC6713493 DOI: 10.1126/sciadv.aav3971] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 07/19/2019] [Indexed: 06/02/2023]
Abstract
Several arguments point to a larger proportion of metal-rich asteroids than that derived from spectral observations, as remnants of collisional disruptions of differentiated bodies. We show experimentally that this apparent deficit may result from the coating of metallic surfaces by silicate melts produced during impacts of hydrated or dry projectiles at typical asteroid impact speeds. Spectral analysis of steel and iron meteorite targets after impact shows a profoundly modified optical signature. Furthermore, hydrated projectiles leave a 3-μm absorption hydration feature. This feature is thus consistent with a metallic surface and does not require an unusual low-speed impact. Unless systematizing radar measurements, ground-based spectral observations can be deceptive in identifying iron-rich bodies. The NASA Psyche mission rendezvous with Psyche will offer the unique opportunity both to measure the relative abundances of regolith and glassy coated surfaces and to substantially increase our understanding of impact processes and signatures on a metal-rich asteroid.
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Affiliation(s)
- Guy Libourel
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
- Hawai‘i Institute of Geophysics and Planetology, School of Ocean, Earth Science and Technology, University of Hawai‘i at Mānoa, Honolulu, HI 96821, USA
| | - Akiko M. Nakamura
- Graduate School of Science, Kobe University, 1-1 Rokkoudai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Pierre Beck
- UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041, France
| | - Sandra Potin
- UJF-Grenoble 1/CNRS-INSU, Institut de Planétologie et d’Astrophysique de Grenoble (IPAG) UMR 5274, Grenoble F-38041, France
| | - Clément Ganino
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Géoazur, 250 rue Albert Einstein, Sophia-Antipolis, 06560 Valbonne, France
| | - Suzanne Jacomet
- MINES Paristech, PSL-Research University, CEMEF-Centre de Mise en Forme des Matériaux/Centre for Material Forming, CNRS UMR 7635, CS 10207, 1 rue Claude Daunesse, 06904 Sophia-Antipolis Cedex, France
| | - Ryo Ogawa
- Graduate School of Science, Kobe University, 1-1 Rokkoudai-cho, Nada-ku, Kobe 657-8501, Japan
| | - Sunao Hasegawa
- Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara 252-5210, Japan
| | - Patrick Michel
- Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, Boulevard de l’Observatoire, CS 34229, 06304 Nice Cedex 4, France
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17
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Lauretta DS, DellaGiustina DN, Bennett CA, Golish DR, Becker KJ, Balram-Knutson SS, Barnouin OS, Becker TL, Bottke WF, Boynton WV, Campins H, Clark BE, Connolly HC, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Enos HL, Hamilton VE, Hergenrother CW, Howell ES, Izawa MRM, Kaplan HH, Nolan MC, Rizk B, Roper HL, Scheeres DJ, Smith PH, Walsh KJ, Wolner CWV. The unexpected surface of asteroid (101955) Bennu. Nature 2019; 568:55-60. [PMID: 30890786 PMCID: PMC6557581 DOI: 10.1038/s41586-019-1033-6] [Citation(s) in RCA: 268] [Impact Index Per Article: 53.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 02/15/2019] [Indexed: 11/09/2022]
Abstract
NASA'S Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft recently arrived at the near-Earth asteroid (101955) Bennu, a primitive body that represents the objects that may have brought prebiotic molecules and volatiles such as water to Earth1. Bennu is a low-albedo B-type asteroid2 that has been linked to organic-rich hydrated carbonaceous chondrites3. Such meteorites are altered by ejection from their parent body and contaminated by atmospheric entry and terrestrial microbes. Therefore, the primary mission objective is to return a sample of Bennu to Earth that is pristine-that is, not affected by these processes4. The OSIRIS-REx spacecraft carries a sophisticated suite of instruments to characterize Bennu's global properties, support the selection of a sampling site and document that site at a sub-centimetre scale5-11. Here we consider early OSIRIS-REx observations of Bennu to understand how the asteroid's properties compare to pre-encounter expectations and to assess the prospects for sample return. The bulk composition of Bennu appears to be hydrated and volatile-rich, as expected. However, in contrast to pre-encounter modelling of Bennu's thermal inertia12 and radar polarization ratios13-which indicated a generally smooth surface covered by centimetre-scale particles-resolved imaging reveals an unexpected surficial diversity. The albedo, texture, particle size and roughness are beyond the spacecraft design specifications. On the basis of our pre-encounter knowledge, we developed a sampling strategy to target 50-metre-diameter patches of loose regolith with grain sizes smaller than two centimetres4. We observe only a small number of apparently hazard-free regions, of the order of 5 to 20 metres in extent, the sampling of which poses a substantial challenge to mission success.
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Affiliation(s)
- D S Lauretta
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA.
| | - D N DellaGiustina
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C A Bennett
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D R Golish
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - T L Becker
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - W F Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - W V Boynton
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H Campins
- Department of Physics, University of Central Florida, Orlando, FL, USA
| | - B E Clark
- Department of Physics and Astronomy, Ithaca College, Ithaca, NY, USA
| | - H C Connolly
- Department of Geology, Rowan University, Glassboro, NJ, USA
| | | | - J P Dworkin
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - J P Emery
- Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, TN, USA
| | - H L Enos
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C W Hergenrother
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E S Howell
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M R M Izawa
- Institute for Planetary Materials, Okayama University-Misasa, Misasa, Japan
| | - H H Kaplan
- Southwest Research Institute, Boulder, CO, USA
| | - M C Nolan
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - B Rizk
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - H L Roper
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D J Scheeres
- Smead Department of Aerospace Engineering, University of Colorado, Boulder, CO, USA
| | - P H Smith
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - C W V Wolner
- Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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18
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Barnouin OS, Daly MG, Palmer EE, Gaskell RW, Weirich JR, Johnson CL, Asad MMA, Roberts JH, Perry ME, Susorney HCM, Daly RT, Bierhaus EB, Seabrook JA, Espiritu RC, Nair AH, Nguyen L, Neumann GA, Ernst CM, Boynton WV, Nolan MC, Adam CD, Moreau MC, Risk B, D'Aubigny CD, Jawin ER, Walsh KJ, Michel P, Schwartz SR, Ballouz RL, Mazarico EM, Scheeres DJ, McMahon J, Bottke W, Sugita S, Hirata N, Hirata N, Watanabe S, Burke KN, DellaGuistina DN, Bennett CA, Lauretta DS. Shape of (101955) Bennu indicative of a rubble pile with internal stiffness. NATURE GEOSCIENCE 2019; 12:247-252. [PMID: 31080497 PMCID: PMC6505705 DOI: 10.1038/s41561-019-0330-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 02/15/2019] [Indexed: 05/18/2023]
Abstract
The shapes of asteroids reflect interplay between their interior properties and the processes responsible for their formation and evolution as they journey through the Solar System. Prior to the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) mission, Earth-based radar imaging gave an overview of (101955) Bennu's shape. Here, we construct a high-resolution shape model from OSIRIS-REx images. We find that Bennu's top-like shape, considerable macroporosity, and prominent surface boulders suggest that it is a rubble pile. High-standing, north-south ridges that extend from pole to pole, many long grooves, and surface mass wasting indicate some low levels of internal friction and/or cohesion. Our shape model indicates that, similar to other top-shaped asteroids, Bennu formed by reaccumulation and underwent past periods of fast spin leading to its current shape. Today, Bennu might follow a different evolutionary pathway, with interior stiffness permitting surface cracking and mass wasting.
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Affiliation(s)
- O S Barnouin
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M G Daly
- The Centre for Research in Earth and Space Science, York University, Toronto, Ontario, Canada
| | - E E Palmer
- Planetary Science Institute, Tucson, AZ, USA
| | - R W Gaskell
- Planetary Science Institute, Tucson, AZ, USA
| | - J R Weirich
- Planetary Science Institute, Tucson, AZ, USA
| | - C L Johnson
- Planetary Science Institute, Tucson, AZ, USA
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - M M Al Asad
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - J H Roberts
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - M E Perry
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - H C M Susorney
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - R T Daly
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - E B Bierhaus
- Lockheed Martin Space Systems Company, Denver, CO, USA
| | | | - R C Espiritu
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - A H Nair
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - L Nguyen
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - G A Neumann
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - C M Ernst
- The Johns Hopkins University Applied Physics Laboratory, Laurel, MD, USA
| | - W V Boynton
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - M C Nolan
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - C D Adam
- KinetX Aerospace, Inc. Simi Valley, CA, USA
| | - M C Moreau
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - B Risk
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - E R Jawin
- Smithsonian Institution National Museum of Natural History, Washington, DC, USA
| | - K J Walsh
- Southwest Research Institute, Boulder, CO, USA
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, CNRS, Laboratoire Lagrange, Nice, France
| | - S R Schwartz
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - R-L Ballouz
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - E M Mazarico
- NASA Goddard Space Flight Center, Greenbelt, MD, USA
| | - D J Scheeres
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - J McMahon
- Department of Aerospace Engineering Sciences, University of Colorado, Boulder, CO, USA
| | - W Bottke
- Southwest Research Institute, Boulder, CO, USA
| | - S Sugita
- University of Tokyo, Tokyo, Japan
| | - N Hirata
- Aizu University, Aizu-Wakamatsu, Japan
| | | | - S Watanabe
- Nagoya University, Nagoya, Japan
- Institute of Space and Astronautical Science, JAXA, Sagamihara, Japan
| | - K N Burke
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | | | - C A Bennett
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
| | - D S Lauretta
- Lunar Planetary Laboratory, University of Arizona, Tucson, AZ, USA
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19
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Sugita S, Honda R, Morota T, Kameda S, Sawada H, Tatsumi E, Yamada M, Honda C, Yokota Y, Kouyama T, Sakatani N, Ogawa K, Suzuki H, Okada T, Namiki N, Tanaka S, Iijima Y, Yoshioka K, Hayakawa M, Cho Y, Matsuoka M, Hirata N, Hirata N, Miyamoto H, Domingue D, Hirabayashi M, Nakamura T, Hiroi T, Michikami T, Michel P, Ballouz RL, Barnouin OS, Ernst CM, Schröder SE, Kikuchi H, Hemmi R, Komatsu G, Fukuhara T, Taguchi M, Arai T, Senshu H, Demura H, Ogawa Y, Shimaki Y, Sekiguchi T, Müller TG, Hagermann A, Mizuno T, Noda H, Matsumoto K, Yamada R, Ishihara Y, Ikeda H, Araki H, Yamamoto K, Abe S, Yoshida F, Higuchi A, Sasaki S, Oshigami S, Tsuruta S, Asari K, Tazawa S, Shizugami M, Kimura J, Otsubo T, Yabuta H, Hasegawa S, Ishiguro M, Tachibana S, Palmer E, Gaskell R, Le Corre L, Jaumann R, Otto K, Schmitz N, Abell PA, Barucci MA, Zolensky ME, Vilas F, Thuillet F, Sugimoto C, Takaki N, Suzuki Y, Kamiyoshihara H, Okada M, Nagata K, Fujimoto M, Yoshikawa M, Yamamoto Y, Shirai K, Noguchi R, Ogawa N, Terui F, Kikuchi S, Yamaguchi T, Oki Y, Takao Y, Takeuchi H, Ono G, Mimasu Y, Yoshikawa K, Takahashi T, Takei Y, Fujii A, Hirose C, Nakazawa S, Hosoda S, Mori O, Shimada T, Soldini S, Iwata T, Abe M, Yano H, Tsukizaki R, Ozaki M, Nishiyama K, Saiki T, Watanabe S, Tsuda Y. The geomorphology, color, and thermal properties of Ryugu: Implications for parent-body processes. Science 2019; 364:252. [PMID: 30890587 DOI: 10.1126/science.aaw0422] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2018] [Accepted: 03/12/2019] [Indexed: 11/02/2022]
Abstract
The near-Earth carbonaceous asteroid 162173 Ryugu is thought to have been produced from a parent body that contained water ice and organic molecules. The Hayabusa2 spacecraft has obtained global multicolor images of Ryugu. Geomorphological features present include a circum-equatorial ridge, east-west dichotomy, high boulder abundances across the entire surface, and impact craters. Age estimates from the craters indicate a resurfacing age of [Formula: see text] years for the top 1-meter layer. Ryugu is among the darkest known bodies in the Solar System. The high abundance and spectral properties of boulders are consistent with moderately dehydrated materials, analogous to thermally metamorphosed meteorites found on Earth. The general uniformity in color across Ryugu's surface supports partial dehydration due to internal heating of the asteroid's parent body.
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Affiliation(s)
- S Sugita
- The University of Tokyo, Tokyo 113-0033, Japan. .,Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan
| | - R Honda
- Kochi University, Kochi 780-8520, Japan
| | - T Morota
- Nagoya University, Nagoya 464-8601, Japan
| | - S Kameda
- Rikkyo University, Tokyo 171-8501, Japan
| | - H Sawada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - E Tatsumi
- The University of Tokyo, Tokyo 113-0033, Japan
| | - M Yamada
- Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan
| | - C Honda
- University of Aizu, Aizu-Wakamatsu 965-8580, 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
| | - T Kouyama
- National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064 Japan
| | - N Sakatani
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - K Ogawa
- Kobe University, Kobe 657-8501, Japan
| | - H Suzuki
- Meiji University, Kawasaki 214-8571, Japan
| | - T Okada
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,The 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
| | - 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
| | - Y Iijima
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - K Yoshioka
- The University of Tokyo, Tokyo 113-0033, Japan
| | - M Hayakawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Cho
- The University of Tokyo, Tokyo 113-0033, Japan
| | - M Matsuoka
- 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
| | - N Hirata
- Kobe University, Kobe 657-8501, Japan
| | - H Miyamoto
- The University of Tokyo, Tokyo 113-0033, Japan
| | - D Domingue
- Planetary Science Institute, Tucson, AZ 85719, USA
| | | | - T Nakamura
- Tohoku University, Sendai 980-8578, Japan
| | - T Hiroi
- Brown University, Providence, RI 02912, USA
| | - T Michikami
- Kindai University, Higashi-Hiroshima 739-2116, Japan
| | - P Michel
- Université Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de le Recherche Scientifique (CNRS), Laboratoire Lagrange, 06304 Nice, France
| | - R-L Ballouz
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan.,University of Arizona, Tucson, AZ 85705, USA
| | - O S Barnouin
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - C M Ernst
- Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA
| | - S E Schröder
- German Aerospace Center (DLR), Institute of Planetary Research, 12489 Berlin, Germany
| | - H Kikuchi
- The University of Tokyo, Tokyo 113-0033, Japan
| | - R Hemmi
- The University of Tokyo, Tokyo 113-0033, Japan
| | - G Komatsu
- International Research School of Planetary Sciences, Università d'Annunzio, 65127 Pescara, Italy.,Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan
| | - T Fukuhara
- Rikkyo University, Tokyo 171-8501, Japan
| | - M Taguchi
- Rikkyo University, Tokyo 171-8501, Japan
| | - T Arai
- Ashikaga University, Ashikaga 326-8558, Japan
| | - H Senshu
- Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan
| | - H Demura
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - Y Ogawa
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - Y Shimaki
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T Sekiguchi
- Hokkaido University of Education, Asahikawa 070-8621, Japan
| | - T G Müller
- Max-Planck-Institut für Extraterrestrische Physik, 85748 Garching, Germany
| | - A Hagermann
- University of Stirling, FK9 4LA, Scotland, UK
| | - T Mizuno
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - H Noda
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - K Matsumoto
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan.,SOKENDAI (The Graduate University for Advanced Studies), Hayama 240-0193, Japan
| | - R Yamada
- University of Aizu, Aizu-Wakamatsu 965-8580, Japan
| | - Y Ishihara
- 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
| | - H Araki
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - K Yamamoto
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - S Abe
- Nihon University, Funabashi 274-8501, Japan
| | - F Yoshida
- Planetary Exploration Research Center, Chiba Institute of Technology, Narashino 275-0016, Japan
| | - A Higuchi
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - S Sasaki
- Osaka University, Toyonaka 560-0043, Japan
| | - S Oshigami
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - S Tsuruta
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - K Asari
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - S Tazawa
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - M Shizugami
- National Astronomical Observatory of Japan, Mitaka 181-8588, Japan
| | - J Kimura
- Osaka University, Toyonaka 560-0043, Japan
| | - T Otsubo
- Hitotsubashi University, Tokyo 186-8601, Japan
| | - H Yabuta
- Hiroshima University, Higashi-Hiroshima 739-8526, Japan
| | - S Hasegawa
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - M Ishiguro
- Seoul National University, Seoul 08826, Korea
| | - S Tachibana
- The University of Tokyo, Tokyo 113-0033, Japan
| | - E Palmer
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - R Gaskell
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - L Le Corre
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - R Jaumann
- German Aerospace Center (DLR), Institute of Planetary Research, 12489 Berlin, Germany
| | - K Otto
- German Aerospace Center (DLR), Institute of Planetary Research, 12489 Berlin, Germany
| | - N Schmitz
- German Aerospace Center (DLR), Institute of Planetary Research, 12489 Berlin, Germany
| | - P A Abell
- NASA Johnson Space Center, Houston, TX 77058, USA
| | - M A Barucci
- Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique (LESIA)-Observatoire de Paris, Paris Sciences et Lettres (PSL), Centre National de le Recherche Scientifique (CNRS), Sorbonne Université, Université Paris-Diderot, 92195 Meudon Principal Cedex, France
| | - M E Zolensky
- NASA Johnson Space Center, Houston, TX 77058, USA
| | - F Vilas
- Planetary Science Institute, Tucson, AZ 85719, USA
| | - F Thuillet
- Université Côte d'Azur, Observatoire de la Côte d'Azur, Centre National de le Recherche Scientifique (CNRS), Laboratoire Lagrange, 06304 Nice, France
| | - C Sugimoto
- The University of Tokyo, Tokyo 113-0033, Japan
| | - N Takaki
- The University of Tokyo, Tokyo 113-0033, Japan
| | - Y Suzuki
- The University of Tokyo, Tokyo 113-0033, Japan
| | | | - M Okada
- The University of Tokyo, Tokyo 113-0033, Japan
| | - K Nagata
- National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064 Japan
| | - M Fujimoto
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, 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
| | - 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
| | - K Shirai
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - R Noguchi
- 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
| | - F Terui
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - S Kikuchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - T Yamaguchi
- Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), Sagamihara 252-5210, Japan
| | - Y Oki
- The University of Tokyo, Tokyo 113-0033, Japan
| | - Y Takao
- The University of Tokyo, Tokyo 113-0033, Japan
| | - H Takeuchi
- 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.,Research and Development Directorate, 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
| | - S Nakazawa
- 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
| | - 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
| | - 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 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
| | - 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
| | - K Nishiyama
- 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 Watanabe
- Nagoya University, Nagoya 464-8601, Japan.,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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20
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Extremely strong polarization of an active asteroid (3200) Phaethon. Nat Commun 2018; 9:2486. [PMID: 29950658 PMCID: PMC6021421 DOI: 10.1038/s41467-018-04727-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 05/14/2018] [Indexed: 11/22/2022] Open
Abstract
The near-Earth asteroid (3200) Phaethon is the parent body of the Geminid meteor stream. Phaethon is also an active asteroid with a very blue spectrum. We conducted polarimetric observations of this asteroid over a wide range of solar phase angles α during its close approach to the Earth in autumn 2016. Our observation revealed that Phaethon exhibits extremely large linear polarization: P = 50.0 ± 1.1% at α = 106.5°, and its maximum is even larger. The strong polarization implies that Phaethon’s geometric albedo is lower than the current estimate obtained through radiometric observation. This possibility stems from the potential uncertainty in Phaethon’s absolute magnitude. An alternative possibility is that relatively large grains (~300 μm in diameter, presumably due to extensive heating near its perihelion) dominate this asteroid’s surface. In addition, the asteroid’s surface porosity, if it is substantially large, can also be an effective cause of this polarization. (3200) Phaethon is a near-Earth asteroid discovered in 1983 that has large inclination and eccentricity. Here, the authors perform polarimetric observation of Phaethon over a wide range of solar phase angle and report that the asteroid exhibits a very strong linear polarization.
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21
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Shinbrot T, Sabuwala T, Siu T, Vivar Lazo M, Chakraborty P. Size Sorting on the Rubble-Pile Asteroid Itokawa. PHYSICAL REVIEW LETTERS 2017; 118:111101. [PMID: 28368621 DOI: 10.1103/physrevlett.118.111101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Indexed: 06/07/2023]
Abstract
Photographs of the asteroid Itokawa reveal unexpectedly strong size segregation between lowlands populated almost entirely by small pebbles and highlands consisting of larger boulders. We propose that this segregation may be caused by a simple and unexplored effect: pebbles accreting onto the asteroid rebound from boulders, but sink into pebbly regions. By number, overwhelmingly more particles on Itokawa are pebbles, and collisions involving these pebbles must unavoidably cause pebbly regions to grow. We carry out experiments and simulations that demonstrate that this mechanism of size sorting based on simple counting of grains produces strong lateral segregation that reliably obeys an analytic formula.
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Affiliation(s)
- Troy Shinbrot
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Tapan Sabuwala
- Continuum Physics Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
| | - Theo Siu
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Miguel Vivar Lazo
- Physics Department, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Pinaki Chakraborty
- Fluid Mechanics Unit, Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0495, Japan
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22
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Super-catastrophic disruption of asteroids at small perihelion distances. Nature 2016; 530:303-6. [PMID: 26887492 DOI: 10.1038/nature16934] [Citation(s) in RCA: 131] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2015] [Accepted: 12/07/2015] [Indexed: 11/09/2022]
Abstract
Most near-Earth objects came from the asteroid belt and drifted via non-gravitational thermal forces into resonant escape routes that, in turn, pushed them onto planet-crossing orbits. Models predict that numerous asteroids should be found on orbits that closely approach the Sun, but few have been seen. In addition, even though the near-Earth-object population in general is an even mix of low-albedo (less than ten per cent of incident radiation is reflected) and high-albedo (more than ten per cent of incident radiation is reflected) asteroids, the characterized asteroids near the Sun typically have high albedos. Here we report a quantitative comparison of actual asteroid detections and a near-Earth-object model (which accounts for observational selection effects). We conclude that the deficit of low-albedo objects near the Sun arises from the super-catastrophic breakup (that is, almost complete disintegration) of a substantial fraction of asteroids when they achieve perihelion distances of a few tens of solar radii. The distance at which destruction occurs is greater for smaller asteroids, and their temperatures during perihelion passages are too low for evaporation to explain their disappearance. Although both bright and dark (high- and low-albedo) asteroids eventually break up, we find that low-albedo asteroids are more likely to be destroyed farther from the Sun, which explains the apparent excess of high-albedo near-Earth objects and suggests that low-albedo asteroids break up more easily as a result of thermal effects.
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23
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Boulders on asteroid Toutatis as observed by Chang'e-2. Sci Rep 2015; 5:16029. [PMID: 26522880 PMCID: PMC4629198 DOI: 10.1038/srep16029] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Accepted: 10/08/2015] [Indexed: 11/23/2022] Open
Abstract
Boulders are ubiquitously found on the surfaces of small rocky bodies in the inner solar system and their spatial and size distributions give insight into the geological evolution and collisional history of the parent bodies. Using images acquired by the Chang’e-2 spacecraft, more than 200 boulders have been identified over the imaged area of the near-Earth asteroid Toutatis. The cumulative boulder size frequency distribution (SFD) shows a steep slope of −4.4 ± 0.1, which is indicative of a high degree of fragmentation. Similar to Itokawa, Toutatis probably has a rubble-pile structure, as most boulders on its surface cannot solely be explained by impact cratering. The significantly steeper slope for Toutatis’ boulder SFD compared to Itokawa may imply a different preservation state or diverse formation scenarios. In addition, the cumulative crater SFD has been used to estimate a surface crater retention age of approximately 1.6 ± 0.3 Gyr.
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24
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Alí-Lagoa V, Delbo’ M, Libourel G. RAPID TEMPERATURE CHANGES AND THE EARLY ACTIVITY ON COMET 67P/CHURYUMOV–GERASIMENKO. ACTA ACUST UNITED AC 2015. [DOI: 10.1088/2041-8205/810/2/l22] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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25
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Cracks in Martian boulders exhibit preferred orientations that point to solar-induced thermal stress. Nat Commun 2015; 6:6712. [PMID: 25813699 DOI: 10.1038/ncomms7712] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2014] [Accepted: 02/20/2015] [Indexed: 11/08/2022] Open
Abstract
The origins of fractures in Martian boulders are unknown. Here, using Mars Exploration Rover 3D data products, we obtain orientation measurements for 1,857 cracks visible in 1,573 rocks along the Spirit traverse and find that Mars rock cracks are oriented in statistically preferred directions similar to those compiled herein for Earth rock cracks found in mid-latitude deserts. We suggest that Martian directional cracking occurs due to the preferential propagation of microfractures favourably oriented with respect to repeating geometries of diurnal peaks in sun-induced thermal stresses. A numerical model modified here with Mars parameters supports this hypothesis both with respect to the overall magnitude of stresses as well as to the times of day at which the stresses peak. These data provide the first direct field and numerical evidence that insolation-related thermal stress potentially plays a principle role in cracking rocks on portions of the Martian surface.
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26
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Hogan JD, Mir CE, Plescia JB, Ramesh K. Dynamic Brittle Fragmentation: Probing the Byproducts of Hypervelocity Impact in Space. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.proeng.2015.04.028] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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27
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Rozitis B, MacLennan E, Emery JP. Cohesive forces prevent the rotational breakup of rubble-pile asteroid (29075) 1950 DA. Nature 2014; 512:174-6. [DOI: 10.1038/nature13632] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Accepted: 06/26/2014] [Indexed: 11/09/2022]
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Affiliation(s)
- Heather A Viles
- School of Geography and the Environment, University of Oxford, Oxford OX1 3QY, UK
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