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Campo del Cielo modeling and comparison with observations: I. Atmospheric entry of the iron meteoroid

This paper presents an attempt to reconstruct the Campo del Cielo (CdC) impact event, that is, to estimate the preatmospheric mass and velocity of the iron meteoroid and pre‐impact parameters of its fragments allowing formation of funnels and impact craters. The goal of this study is to improve the understanding of the effects small‐scale iron meteoroids can have on the Earth's surface. We model the meteoroid's atmospheric flight taking deceleration, ablation, and fragmentation into account, and then compare the results with available observations. We found that a fragment's velocity near the surface should be <1 km s−1 in order to form a funnel with an intact meteorite inside. The estimates of preatmospheric (at an altitude of 100 km) parameters of the CdC impact event are as follows: minimal mass of 7500–8500 t, which corresponds to a diameter range of 12.2–12.8 m; maximum entry angle above the atmosphere of ~16.5° and velocities of 14.5–18.4  km s−1, which is close to the one most frequently reached by Near‐Earth objects (NEOs). Near the surface, the largest fragments with a mass of 400–1500 t and velocities of 4–7 km s−1 form impact craters whereas fragments with a mass <31 t and velocities <1 km s−1 form funnels. Masses <3 t are not included in our simulations. Their total mass is 280–460 t at the point of disruption but <110 t on the Earth's surface. These numerous small fragments are dispersed over a large area and are very popular among meteorite hunters and dealers. In spite of all the observed crater location/size data and impactor velocity limits from the models, there are far more free parameters than constraints. As a result, any values for preatmospheric mass, velocity, and entry angle are merely representative or limitative as opposed to true values.