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首页> 外文期刊>Icarus: International Journal of Solar System Studies >Surface morphological features of boulders on Asteroid 25143 Itokawa
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Surface morphological features of boulders on Asteroid 25143 Itokawa

机译:小行星25143丝川上巨石的表面形态特征

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摘要

On the sub-kilometer S-type asteroid, 25143 Itokawa, some boulders on rough terrains seem to be exposed without any powdery material covering. Based on surface morphological features, there are two major types of boulders: one has rounded edges and corners (rounded boulders), while the other has angular edges and corners (angular boulders). The surface features of the rounded boulders suggest that they have hardness heterogeneity and that some may be breccias. The angular boulders appear to be more resistant to impact disruption than the rounded ones, which may be due to a difference in lithology. The major constituents of Itokawa may be LL chondrite-like brecciated lithology (rounded boulders) along with a remarkable number of boulders suggesting that lithology is atypical among LL chondrites (angular boulders). Some of both types of boulders contain intersecting and stepped planar foliations. Comparison with meteorite ALH76009 suggests that the planar foliations may be marks where rocks were torn apart. As lithified breccias cannot be formed on present-day sub-kilometer-sized Itokawa, it is reasonable that boulders with various lithologies on Itokawa were formed on its large ancestor(s). The rubble-pile structure of Itokawa suggested by its low density (~1.9 g/cm~3) indicates that boulders on Itokawa are reassembled fragments formed by catastrophic disruption of large ancestor(s).
机译:在亚公里S型小行星25143 Itokawa上,崎rough地形上的一些巨石似乎裸露在外,没有任何粉状物质覆盖。根据表面形态特征,有两种主要类型的巨石:一种具有圆形的边缘和角(圆形巨石),而另一种则具有角形的边缘和角(角巨石)。圆形巨石的表面特征表明它们具有硬度异质性,有些可能是角砾岩。角砾岩似乎比圆形巨石更能抵抗冲击破坏,这可能是由于岩性不同。丝川的主要成分可能是LL角陨石状的角砾岩性(圆形巨石),还有大量的巨石表明LL球状陨石(角巨石)中的岩性是非典型的。两种类型的巨石都包含相交的和阶梯状的平面叶。与陨石ALH76009的比较表明,平面页岩可能是岩石撕裂的标记。由于目前的亚千米大小的Itokawa无法形成片状角砾岩,因此在Itokawa的大祖先上形成具有各种岩性的巨石是合理的。低密度(〜1.9 g / cm〜3)表明,伊藤川市的瓦砾堆结构表明,伊藤川市的巨石是由大祖先的灾难性破坏形成的重新组装的碎片。

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