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

霍华德陨石属于分异陨石中最丰富的一组，即霍华德-欧长岩-闪长岩（HED）组。这些无球粒陨石被认为来自灶神星4号，它是火星和木星之间主要小行星带中的第二大天体。霍华德岩是灶神星表面岩石，即破碎角砾岩，是灶神星现存岩性最完整的样品集。美国宇航局正在进行的小行星带任务（黎明号）将最终证明HEDs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，了解这个陨石亚类的各个组成部分和类别是至关重要的。到目前为止，大部分的焦点都放在了霍华德铁矿体化学上，只有少数样品被详细描述过。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。该项目的目标是全面概述howardites中的岩石成分及其对HEDs形成的影响，即Vesta的岩石成因。此外，了解灶神星的进化史将有助于了解早期太阳系中小型行星的过程和演化。

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.