Unusual Space Weathering on a CE-5 Metal Grain Indicates Deceptive Surface Signatures of M-type Asteroids
M-type asteroids are historically thought to be exposed metallic cores of differentiated planets with a composition dominated by pure iron and nickel. However, recent spectral and radar observations reveal an insufficient number of M-type asteroids in the main belt. Here, we report unusual space wea...
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Main Authors: | , , , , , , , |
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Format: | Article |
Language: | English |
Published: |
IOP Publishing
2025-01-01
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Series: | The Astrophysical Journal Letters |
Subjects: | |
Online Access: | https://doi.org/10.3847/2041-8213/ada559 |
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Summary: | M-type asteroids are historically thought to be exposed metallic cores of differentiated planets with a composition dominated by pure iron and nickel. However, recent spectral and radar observations reveal an insufficient number of M-type asteroids in the main belt. Here, we report unusual space weathering characteristics associated with a natural metal grain found in Chang'e 5 lunar soil. Microcraters, impact glass, iron whiskers, and unique vesicular rims on the surface of this grain help to explain the unusual properties of some potential M-type asteroids, including low thermal inertia and density. Our findings indicate that space weathering processes, including micrometeorite bombardment and solar wind irradiation, conceal the real surface signatures of M-type asteroids. Furthermore, the presence of He and Ge alloy on the metal grain suggests that M-type asteroids are not only a large metallic Fe and Ni reservoir but also a potential source of noble gases and precious metals. |
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ISSN: | 2041-8205 |