It remains contentious whether the meteoritic material delivered to the terrestrial planets after the end of core formation was rich or poor in water and other volatiles. As Venus’s atmosphere has probably experienced less volatile recycling over its history than Earth’s, it may be possible to constrain the volatile delivery to the primitive Venusian atmosphere from the planet’s present-day atmospheric composition. Here we investigate the long-term evolution of Venus using self-consistent numerical simulations of global thermochemical mantle convection coupled with both an atmospheric evolution model and a late accretion N-body delivery model. We found that atmospheric escape is only able to remove a limited amount of water over the history of the planet, and that the late accretion of wet material exceeds this sink and would result in a present-day atmosphere that is too rich in volatiles. A preferentially dry composition of the late accretion impactors is most consistent with measurements of atmospheric H₂O, CO₂ and N₂. Hence, we suggest that the late accreted material delivered to Venus was mostly dry enstatite chondrite, consistent with isotopic data for Earth, with less than 2.5% (by mass) wet carbonaceous chondrites. In this scenario, the majority of Venus’s and Earth’s water would have been delivered during the main accretion phase.

在岩心形成结束后输送到地面行星的气象材料中的水和其他挥发物的富与少仍然有争议。由于金星的大气在其历史上经历的挥发循环次数可能少于地球，因此可能有可能将挥发物从当今行星的大气成分输送到原始的金星大气中。在这里，我们使用全球热化学地幔对流的自洽数值模拟，结合大气演化模型和后期积聚的N体传递模型，研究了金星的长期演化。我们发现，大气逃逸仅能清除地球历史上有限的水分，并且湿物料的后期积聚超过了该下沉，将导致当今的大气中挥发物过多。后期积聚撞击物的优先干燥成分与大气H的测量最一致₂ O，CO ₂和N ₂。因此，我们建议输送到金星的后期积积物质主要是干顽辉辉石球粒陨石，与地球的同位素数据一致，湿碳质球粒陨石少于2.5％（按质量计）。在这种情况下，金星和地球的大部分水将在主要增生阶段被输送。