论文标题
对早期地球的巨大影响：行星灭菌和铁输送
Large Impacts onto the Early Earth: Planetary Sterilization and Iron Delivery
论文作者
论文摘要
晚期积聚到Hadean Earth上的巨大影响可能会影响早期的居住能力，无论是通过提供所需的铁所需的铁所需的铁所需的铁而造成生命的起源，从而影响了早期的宜居性。我们提出了直径为1500-3400 km的3D数值模拟对地球早期的影响，以量化其对行星居住性的影响。我们发现，灭菌影响事件需要比以前假设的更大的弹丸，并且直径为2000-2700 km的冲击器才能完全融化地球表面，并且外推> 700 km的直径直径为海洋蒸发所需的直径。我们还发现，在影响很大的情况下，减少环境的可能性较小，因为> 70％的弹丸铁被沉积在地壳和上层地幔中，在那里无法立即使用以减少地表水并形成还原的气氛。尽管最大的预期后积聚影响（〜1个月球质量）向大气中输送了足够的铁，以减少整个海洋水，但这种影响也会融化整个表面，潜在地隔离凝结的凝结铁，而不会迅速氧化。在巨大影响后出现生命的假说需要有效的机制来利用在地壳/地幔中隔离铁的减少能力，或者是在更弱减少的后影响后环境中运行的生命途径的起源，这些环境需要较小的撞击量造成的撞击量。
Late accretion onto the Hadean Earth included large impacts that could have influenced early habitability, either by sterilizing the planet or alternatively catalyzing the origin of life by delivering iron required to create a reducing environment/atmosphere. We present 3D numerical simulations of 1500-3400 km diameter impacts on the early Earth in order to quantify their effects on planetary habitability. We find sterilizing impact events require larger projectiles than previously assumed, with a 2000-2700 km diameter impactor required to completely melt Earth's surface and an extrapolated >700 km diameter impactor required for ocean-vaporization. We also find that reducing environments are less likely to arise following large impacts than previously suggested, because >70% of the projectile iron is deposited in the crust and upper mantle where it is not immediately available to reduce surface water and contribute to forming a reducing atmosphere. Although the largest expected late accretion impacts (~1 lunar mass) delivered sufficient iron to the atmosphere to have reduced an entire ocean mass of water, such impacts would also have melted the entire surface, potentially sequestering condensing iron that is not oxidized quickly. The hypothesis that life emerged in the aftermath of large impacts requires an efficient mechanism of harnessing the reducing power of iron sequestered in the crust/mantle, or an origin of life pathway that operates in more weakly-reducing post-impact environments that require smaller quantities of impact-delivered iron.
