Bolide light curve systematics from 75 recovered meteorites

Abstract

How does the energy deposition profile (light curve), deceleration, and penetration depth in Earth's atmosphere depend on asteroid composition and meteorite type? Here, we present the light curve and velocity profile of 75 bolides from camera-documented meteorite falls. The light curves as a function of altitude generally develop in the following seven phases: Phase (1) an initial rapid brightening; (2) a gradual increase that sometimes shows periodic brightness variations; (3) an onset and rapid increase of brightness until reaching a plateau; (4) a plateau with occasionally chirping brightness oscillations; (5) flares that result in fragments in the meteor wake; (6) an end flare of sometimes different color; and (7) ongoing ablation and fragmentation until dark flight. These seven phases are interpreted as resulting from solid bodies that cause early brightness oscillations from meteoroid spin, a plateau because of melting and reaching melting equilibrium, chirping oscillations due to plasma instabilities, flares due to fragmentations along fractures from dynamic pressure and thermal stress, and an end flare when the surviving back of the meteoroid explodes. This paper discusses the systematics of how the phase heights depend on entry speed, entry angle, initial mass, and meteorite type. The dynamic pressures during the onset of fragmentation and the end flare correlate with the tensile strength of the recovered meteorites. The results have implications for Planetary Defense when anticipating the energy deposition curve of small solid-body airbursting asteroid impacts like Chelyabinsk.