Bland P A, Artemieva N A
Department of Earth Science and Engineering, Exhibition Road, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Nature. 2003 Jul 17;424(6946):288-91. doi: 10.1038/nature01757.
Accurate modelling of the interaction between the atmosphere and an incoming bolide is a complex task, but crucial to determining the fraction of small asteroids that actually hit the Earth's surface. Most semi-analytical approaches have simplified the problem by considering the impactor as a strengthless liquid-like object ('pancake' models), but recently a more realistic model has been developed that calculates motion, aerodynamic loading and ablation for each separate particle or fragment in a disrupted impactor. Here we report the results of a large number of simulations in which we use both models to develop a statistical picture of atmosphere-bolide interaction for iron and stony objects with initial diameters up to approximately 1 km. We show that the separated-fragments model predicts the total atmospheric disruption of much larger stony bodies than previously thought. In addition, our data set of >1,000 simulated impacts, combined with the known pre-atmospheric flux of asteroids with diameters less than 1 km, elucidates the flux of small bolides at the Earth's surface. We estimate that bodies >220 m in diameter will impact every 170,000 years.
准确模拟大气与来袭火流星之间的相互作用是一项复杂的任务，但对于确定实际撞击地球表面的小天体比例至关重要。大多数半解析方法通过将撞击体视为无强度的类液体物体（“煎饼”模型）来简化问题，但最近已开发出一种更现实的模型，该模型可计算破裂撞击体中每个单独颗粒或碎片的运动、气动载荷和烧蚀情况。在此，我们报告大量模拟的结果，其中我们使用这两种模型来构建初始直径达约1千米的铁质和石质物体的大气 - 火流星相互作用的统计图景。我们表明，分离碎片模型预测的石质天体的大气完全破裂情况比之前认为的要多得多。此外，我们超过1000次模拟撞击的数据集，结合已知的直径小于1千米的小行星的大气前通量，阐明了地球表面小火流星的通量。我们估计直径大于220米的天体每17万年就会撞击一次。
