Lithological diversity among howardites and its implications for the HED parent body

霍华德陨石属于最丰富的分化陨石组，霍华德陨石-钙铝榴石-闪长岩（HED）套件。这些无球粒陨石被认为是来自灶神星4，它是火星和木星之间的主小行星带中的第二大天体。霍华德岩是表层岩石，即，碎片角砾岩，包括最完整的样本集的岩性存在灶神星。美国宇航局正在进行的小行星带（黎明）使命将最终证明HED和灶神星之间的遗传联系。对小行星表面的遥感探测将返回可能与霍华德陨石的化学特征相匹配的数据。在这种情况下，至关重要的是要知道这个陨石子类的各个组成部分和类别。到目前为止，许多焦点已经放在霍华德石体化学，只有少数样品已被详细描述。就广泛的岩石学调查和寻找可能的系统成分变化而言，存在缺陷。本项目的目的是对霍瓦迪岩中的石质成分及其对HEDs形成的意义进行全面的概述，即：例如，灶神星的岩石成因。此外，了解灶神星的演化历史将有助于了解早期太阳系中小行星的过程和演化。

Howardites belong to the most abundant group of differentiated meteorites, the howardite-eucrite-diogenite (HED) suite. These achondrites are believed to originate from 4 Vesta, the second largest body in the main asteroid belt between Mars and Jupiter. Howardites are surface rocks, i.e., fragmental breccias, comprising the most complete sample set of lithologies existing on Vesta. The ongoing NASA mission to the asteroid belt (Dawn) is set to ultimately prove the genetic link between HEDs and Vesta. Remote sensing exploration of the asteroid’s surface will return data that can potentially be matched with the chemical features of howardites. In this context, it is crucial to know the individual components and categories of this meteorite subclass. So far, much focus has been placed on howardite bulk chemistry, and only few samples have been described in detail. Deficits exist as far as an extensive petrologic survey and the search for possible systematic compositional variations are concerned. It is the goal of this project to give a comprehensive overview of lithic ingredients in howardites and their implications for the formation of HEDs, i. e., Vesta’s petrogenesis. In addition, learning about the evolutionary history of Vesta will contribute to understanding the processes and evolution of small planetesimals in the early Solar System.