Lithologies of Dimorphos revealed by boulder morphological classes

IF 3 2区物理与天体物理 Q2 ASTRONOMY & ASTROPHYSICS

Icarus Pub Date : 2025-07-19 DOI:10.1016/j.icarus.2025.116744

F. Tusberti , M. Pajola , L. Penasa , A. Lucchetti , M. Massironi , G. Munaretto , J. Beccarelli , R. Pozzobon , C. Rossi , G. Poggiali , N. Murdoch , C.Q. Robin , A. Duchene , M. Amoroso , I. Bertini , J.R. Brucato , A. Capannolo , S. Caporali , M. Ceresoli , G. Cremonese , L. Gomez Casajus

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引用次数: 0

Abstract

The stony/Sq-type binary system (65803) Didymos consists of two rubble pile bodies, Didymos, the primary, and its moonlet Dimorphos. In 2022, the first planetary defense mission Double Asteroid Redirection Test (DART) reached Dimorphos and collected unprecedented high-resolution images of its surface. They revealed a variegated surface completely covered by stacked boulders and cobbles with different shapes and textures. Their morphological heterogeneity likely reflects the lithologies originally present within the Didymos and Dimorphos' parent body, before its fragmentation.

We present a lithologic study of Dimorphos' surface, based on a morphological analysis of its boulders. Our approach considers each boulder's 2D outline, perceived 3D shape, and surface texture characteristics. Based on these features, we identified two main morphological classes. A total of 178 boulders were classified as Angular morphology covering 38.5 % of the mapped area. This type is characterized by cohesive boulders with straight and angular outlines as well as sharp three-dimensional edges, which form well-defined sub-planar facets. Additionally, the texture of this kind of rocks show low-to-mid Roughness and the presence of lineations on some boulders. On the other hand, 210 boulders were categorized as Hummocky morphology, which covers 61.5 % of the area. Such morphology appears more friable and features boulders with rounded shaped and ragged and irregular 2D perimeter. Their 3D perceived shape appears as flat-to-curve, with rough and hummocky surface textures due to embedded clasts. We interpret the Hummocky morphology as breccia lithology. On the other hand, although Angular morphology can be associated with multiple potential lithologies, we interpret it as either an achondritic/igneous lithology or a highly metamorphosed chondritic lithology. The breccias are likely characteristic of the parent body's outer layers, actively involved in impact and sedimentary processes. Conversely, the lithologies associated with the An morphology should represent deeper regions of the plantesimal, possibly exhumed by impacts. All these results will be further complemented by data from the Hera mission, which will arrive at (65803) Didymos system at the end of 2026.

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由岩石形态分类揭示的二形态龙的岩性

石质/ sq型双星系统（65803）Didymos由两个碎石堆体组成，主要是Didymos和它的小卫星Dimorphos。2022年，第一个行星防御任务“双小行星重定向测试”（DART）到达了Dimorphos，并收集了前所未有的高分辨率表面图像。它们揭示了一个杂色的表面，完全被不同形状和纹理的堆积的巨石和鹅卵石覆盖。它们的形态异质性可能反映了Didymos和Dimorphos母体在破碎之前的原始岩性。基于对其巨石的形态分析，我们对Dimorphos的表面进行了岩性研究。我们的方法考虑了每个巨石的2D轮廓，感知的3D形状和表面纹理特征。基于这些特征，我们确定了两个主要的形态学类。共有178块巨石被归类为棱角形态，占地图面积的38.5%。这种类型的特点是有凝聚力的巨石，具有笔直和有角的轮廓，以及锋利的三维边缘，形成明确的亚平面切面。此外，这种岩石的纹理显示出低到中等的粗糙度，并且在一些巨石上存在线条。另一方面，210块巨石被归类为丘状形态，占面积的61.5%。这样的形态显得更加脆弱，其特征是圆形的巨石和粗糙不规则的二维周长。它们的3D感知形状呈现为平面到曲线，由于嵌入的碎屑，表面纹理粗糙且凹凸不平。我们认为Hummocky形态为角砾岩岩性。另一方面，尽管角状形态可以与多种潜在的岩性相关联，但我们将其解释为球粒岩/火成岩岩性或高度变质的球粒岩岩性。角砾岩可能是母体外层的特征，积极参与了撞击和沉积过程。相反，与An形态相关的岩性应该代表更深的植物动物区域，可能是由撞击挖掘出来的。所有这些结果将由Hera任务的数据进一步补充，该任务将于2026年底到达（65803）Didymos系统。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Icarus 地学天文-天文与天体物理

CiteScore

6.30

自引率

18.80%

发文量

356

审稿时长

2-4 weeks

期刊介绍： Icarus is devoted to the publication of original contributions in the field of Solar System studies. Manuscripts reporting the results of new research - observational, experimental, or theoretical - concerning the astronomy, geology, meteorology, physics, chemistry, biology, and other scientific aspects of our Solar System or extrasolar systems are welcome. The journal generally does not publish papers devoted exclusively to the Sun, the Earth, celestial mechanics, meteoritics, or astrophysics. Icarus does not publish papers that provide "improved" versions of Bode''s law, or other numerical relations, without a sound physical basis. Icarus does not publish meeting announcements or general notices. Reviews, historical papers, and manuscripts describing spacecraft instrumentation may be considered, but only with prior approval of the editor. An entire issue of the journal is occasionally devoted to a single subject, usually arising from a conference on the same topic. The language of publication is English. American or British usage is accepted, but not a mixture of these.