Small Near-Earth Asteroids as a Source of Meteorites

TL;DR

This paper reviews how small near-Earth asteroids become meteorites, analyzing bolide observations to understand asteroid properties, impact flux, and atmospheric entry processes, with insights from notable meteorite falls.

Contribution

It compiles and analyzes observational data on bolides and meteorite falls, providing new insights into asteroid composition, impact processes, and the flux of small bodies impacting Earth.

Findings

22 instrumentally observed meteorite falls analyzed

Revolutionary insights from Almahata Sitta and Benešov meteorites

Chelyabinsk fall caused significant blast damage

Abstract

Small asteroids intersecting Earth's orbit can deliver extraterrestrial rocks to the Earth, called meteorites. This process is accompanied by a luminous phenomena in the atmosphere, called bolides or fireballs. Observations of bolides provide pre-atmospheric orbits of meteorites, physical and chemical properties of small asteroids, and the flux (i.e. frequency of impacts) of bodies at the Earth in the centimeter to decameter size range. In this chapter we explain the processes occurring during the penetration of cosmic bodies through the atmosphere and review the methods of bolide observations. We compile available data on the fireballs associated with 22 instrumentally observed meteorite falls. Among them are the heterogeneous falls Almahata Sitta (2008 TC$_3$) and Bene\v{s}ov, which revolutionized our view on the structure and composition of small asteroids, the P\v{r}\'{\i}bram-Neuschwanstein orbital pair, carbonaceous chondrite meteorites with orbits on the asteroid-comet boundary, and the Chelyabinsk fall, which produced a damaging blast wave. While most meteoroids disrupt into fragments during atmospheric flight, the Carancas meteoroid remained nearly intact and caused a crater-forming explosion on the ground.