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A robust method to measure large meteoroids colliding with the atmosphere

Meteoroids are fragments of asteroids which travel across the interplanetary medium. Although the Earth's atmosphere is bombarded by decimeter-size objects multiple times per day, a precise measurement of their size is poorly constrained. It is known that the larger they are, the lesser the chance of an impact with the Earth. However, their size is just too small to be observed by telescopes.

In a recent study, a more robust method of measuring fireballs was proposed. The semi-empirical relation is based on the entry mass of well known objects of ton-TNT scale impact energy, and their measured radiation. This relation takes as input the fireball radiated light along the atmospheric trajectory, to estimate the source energy of the meteoroid.

This photometric-based method is becoming be very accessible to use since the optical fireball networks are increasing both in number and size. Thus, a next step is to derive a more accurate size-frequency distribution of the meteoroids, and constrain the risk involved in expanding the space-based infrastructure.

The chart to the right shows energy calibrations of well known bolides around the ton-scale TNT. The error bar on the source energy represents the combined uncertainties from mass and velocity. The thin black line is the fit obtained by (Brown et al. 2002) corresponding to source energies greater than 0.1 kt TNT. This is continued with the dotted grey line onto this energy category. The red line is obtained as a best fit of the calibrated impact energy of bolides. The displayed objects have well studied trajectory data, and all except the small circles with black contour were the subject of successful meteorite recovery campaigns. The 100% luminous efficiency correspondence is represented by the thick line.

More information: This research was presented in a paper published in “Monthly Notices of the Royal Astronomical Society” (

Published on: Jan 25, 2022

Energy calibrations of well known bolides around the ton-scale TNT

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