Meteoroids are small bodies of extraterrestrial material that enter the Earth’s atmosphere, creating streaks of light called meteors. If they survive their passage through the atmosphere and land on Earth, they become meteorites and settle in littered fields. A scattered field is the area over which meteorites are scattered from a single fall, usually tens of kilometers in length. Since falling meteorites can provide large amounts of kinetic energy and are therefore potentially dangerous, the study of the physical properties, trajectory, velocity and entry angle of a meteoroid is d of paramount importance.
The Aletai meteorite is a metallic iron meteorite of which 74 tons were recovered from the Aletai region in Xinjiang province in China. The total length of the field dotted with Aletai is 430 kilometers, the longest known to date. To understand how this impact event generated such a widespread distribution of meteorite fragments, Ye Li and his colleagues at the Chinese Academy of Sciences’ Purple Mountain Observatory combined analyzes from petrology and geochemistry. of the meteorite, with radionuclide analyzes and numerical modeling, to estimate the depths from which these fragments were derived in the meteoroid. This led to estimates of the meteoroid’s mass, as well as its speed and angle of entry.
The results of this work indicated that the Aletai meteoroid, which mainly consists of the mineral kamacite (Fe-Ni alloy), had a low angle of entry into the Earth’s atmosphere. Numerical modeling of its trajectory, based on mass, velocity and angle of entry, indicated that rock-hopping-like behavior was responsible for the unusual length of the scattered field. Rock-jumping trajectories could cause a meteoroid to dissipate a long-lasting energy into the atmosphere rather than the ground, making it potentially less dangerous. These new results could help determine if other large sparse fields are the result of similar dynamics in Earth’s atmosphere. READ MORE