Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs
Abstract The shapes of regolith particles on airless bodies, such as the Moon and asteroids, are important to understand their formation and evolution on surfaces. Limited studies have shown that the three-dimensional (3D) shapes of lunar regolith particles are, on average, more equant (spherical) t...
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| Format: | Article |
| Language: | English |
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SpringerOpen
2022-11-01
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| Series: | Earth, Planets and Space |
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| Online Access: | https://doi.org/10.1186/s40623-022-01737-9 |
| _version_ | 1811304638751703040 |
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| author | Akira Tsuchiyama Takashi Sakurama Tsukasa Nakano Kentaro Uesugi Makiko Ohtake Takashi Matsushima Kazuo Terakado Erik M. Galimov |
| author_facet | Akira Tsuchiyama Takashi Sakurama Tsukasa Nakano Kentaro Uesugi Makiko Ohtake Takashi Matsushima Kazuo Terakado Erik M. Galimov |
| author_sort | Akira Tsuchiyama |
| collection | DOAJ |
| description | Abstract The shapes of regolith particles on airless bodies, such as the Moon and asteroids, are important to understand their formation and evolution on surfaces. Limited studies have shown that the three-dimensional (3D) shapes of lunar regolith particles are, on average, more equant (spherical) than those of asteroid Itokawa or fragments by impact experiments. Therefore, more studies are required to determine whether such a feature is common. Accordingly, we performed X-ray microtomography imaging of lunar regolith particles collected by the Apollo program by NASA and the Luna program by the Soviet Union to obtain their 3D shapes. The ten samples (65 to 1108 particles/sample) examined had varieties of sampling sites (maria and highlands), reflecting the difference in materials (basalts and anorthosites, respectively, in general), regolith maturities, particle size ranges (< 74 to 450 µm), and petrographic textures (monomineralic, polymineralic, and agglutinate). The 3D particle shape distributions regarding three-axial length ratios (L:I:S, where L, I, and S are the longest, intermediate, and shortest lengths, respectively) showed that the average three-axial ratios were almost similar among the samples, irrespective of the sampling sites, maturities, and the size ranges [S/I = 0.770(8), I/L = 0.758(10), and S/L = 0.581(11) for whole samples]. The 3D shapes of lunar particles were more equant (spherical) than those of the particles collected from asteroid Itokawa and fragments by hypervelocity impact experiments which had the average ratios similar to the 2D silver ratio (S/I = I/L = 0.707 and S/L = 0.500). These findings showed that the balance between impact fragmentation and mechanical abrasion controls the 3D shapes of lunar particles because impact and particle motion on the Moon’s surface occur for a longer duration; however, impact fragmentation on this small asteroid surface primarily controls those of Itokawa particles. We also found shape dependence on petrographic textures of the lunar particles, and this could be explained by the strength of the materials against abrasion. The results obtained in this study will be the basic data to be compared with upcoming new results, such as particles collected from asteroid Ryugu, possibly from asteroid Bennu and Martian moons. Graphical Abstract |
| first_indexed | 2024-04-13T08:10:54Z |
| format | Article |
| id | doaj.art-fa5ed5eea2054b899739a78a432110a4 |
| institution | Directory Open Access Journal |
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| language | English |
| last_indexed | 2024-04-13T08:10:54Z |
| publishDate | 2022-11-01 |
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| series | Earth, Planets and Space |
| spelling | doaj.art-fa5ed5eea2054b899739a78a432110a42022-12-22T02:55:01ZengSpringerOpenEarth, Planets and Space1880-59812022-11-0174111110.1186/s40623-022-01737-9Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programsAkira Tsuchiyama0Takashi Sakurama1Tsukasa Nakano2Kentaro Uesugi3Makiko Ohtake4Takashi Matsushima5Kazuo Terakado6Erik M. Galimov7Research Organization of Science and Technology, Ritsumeikan UniversityDivision of Earth and Planetary Sciences, Graduate School of Science, Kyoto UniversityThe Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST)The Scattering and Imaging Division, Japan Synchrotron Radiation Research Institute (JASRI)Department of Computer Science and Engineering/Division of Information Systems, The University of AizuInstitute of Systems and Information Engineering, University of TsukubaJapan Space ForumV.I. Vernadsky Institute of Geochemistry and Analytical ChemistryAbstract The shapes of regolith particles on airless bodies, such as the Moon and asteroids, are important to understand their formation and evolution on surfaces. Limited studies have shown that the three-dimensional (3D) shapes of lunar regolith particles are, on average, more equant (spherical) than those of asteroid Itokawa or fragments by impact experiments. Therefore, more studies are required to determine whether such a feature is common. Accordingly, we performed X-ray microtomography imaging of lunar regolith particles collected by the Apollo program by NASA and the Luna program by the Soviet Union to obtain their 3D shapes. The ten samples (65 to 1108 particles/sample) examined had varieties of sampling sites (maria and highlands), reflecting the difference in materials (basalts and anorthosites, respectively, in general), regolith maturities, particle size ranges (< 74 to 450 µm), and petrographic textures (monomineralic, polymineralic, and agglutinate). The 3D particle shape distributions regarding three-axial length ratios (L:I:S, where L, I, and S are the longest, intermediate, and shortest lengths, respectively) showed that the average three-axial ratios were almost similar among the samples, irrespective of the sampling sites, maturities, and the size ranges [S/I = 0.770(8), I/L = 0.758(10), and S/L = 0.581(11) for whole samples]. The 3D shapes of lunar particles were more equant (spherical) than those of the particles collected from asteroid Itokawa and fragments by hypervelocity impact experiments which had the average ratios similar to the 2D silver ratio (S/I = I/L = 0.707 and S/L = 0.500). These findings showed that the balance between impact fragmentation and mechanical abrasion controls the 3D shapes of lunar particles because impact and particle motion on the Moon’s surface occur for a longer duration; however, impact fragmentation on this small asteroid surface primarily controls those of Itokawa particles. We also found shape dependence on petrographic textures of the lunar particles, and this could be explained by the strength of the materials against abrasion. The results obtained in this study will be the basic data to be compared with upcoming new results, such as particles collected from asteroid Ryugu, possibly from asteroid Bennu and Martian moons. Graphical Abstracthttps://doi.org/10.1186/s40623-022-01737-9X-ray tomographyThree-axial ratioAirless bodyImpactAbrasionAsteroid Itokawa |
| spellingShingle | Akira Tsuchiyama Takashi Sakurama Tsukasa Nakano Kentaro Uesugi Makiko Ohtake Takashi Matsushima Kazuo Terakado Erik M. Galimov Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs Earth, Planets and Space X-ray tomography Three-axial ratio Airless body Impact Abrasion Asteroid Itokawa |
| title | Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs |
| title_full | Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs |
| title_fullStr | Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs |
| title_full_unstemmed | Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs |
| title_short | Three-dimensional shape distribution of lunar regolith particles collected by the Apollo and Luna programs |
| title_sort | three dimensional shape distribution of lunar regolith particles collected by the apollo and luna programs |
| topic | X-ray tomography Three-axial ratio Airless body Impact Abrasion Asteroid Itokawa |
| url | https://doi.org/10.1186/s40623-022-01737-9 |
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