Abundances of the highly siderophile elements (HSEs) in silicate portions of Earth and the Moon provide constraints on the impact flux to both bodies, but only since ~100 Myr after the beginning of the Solar System (hereafter t_CAI). The earlier impact flux to the inner Solar System remains poorly constrained. The former dwarf planet Vesta offers the possibility to probe this early history, because it underwent rapid core formation ~1 Myr after t_CAI and its silicate portions possess elevated chondritic HSE abundances. Here we quantify the material accreted into Vesta’s mantle and crust and find that the HSE abundances can only be explained by the bombardments of planetesimals from the terrestrial planet region. The Vestan mantle accreted HSEs within the first 60 Myr; its crust accreted HSEs throughout the Solar System history, with asteroid impacts dominating only since ~4.1 billion years ago. Our results indicate that all major bodies in the inner Solar System accreted planetesimals predominantly from the terrestrial planet region. The asteroid belt was either never significantly more massive than today, or it rapidly lost most of its mass early in the Solar System history.

地球和月球的硅酸盐部分中丰富的高度亲铁元素 (HSE) 限制了对这两个天体的冲击通量，但仅在太阳系开始后约 100 Myr 之后（以下称为t _CAI）。早期对太阳系内部的冲击通量仍然受到很差的限制。前矮行星灶神星提供了探索这一早期历史的可能性，因为它在t _{CAI之后经历了快速的核心形成~1 Myr}其硅酸盐部分具有较高的球粒状 HSE 丰度。在这里，我们量化了吸积到灶神星地幔和地壳中的物质，发现 HSE 丰度只能通过来自类地行星区域的小行星轰击来解释。Vestan地幔在前60 Myr内增加了HSE；它的地壳在整个太阳系历史中都积累了 HSE，小行星撞击仅在大约 41 亿年前才占主导地位。我们的研究结果表明，太阳系内部的所有主要天体都吸积了主要来自类地行星区域的小行星。小行星带要么从来没有比今天大得多，要么在太阳系历史的早期迅速失去了大部分质量。