Speaker
Description
Solar System objects impact Earth’s atmosphere daily, but their small size makes them undetectable before atmospheric entry. To better understand these impactors, we need multi-instrument observations of their disintegration phase [1].
In this study we explore several methods of measuring the pre-atmospheric mass of meteoroids with well-known trajectory, at the source of ton TNT-scale atmospheric impacts [2]. On this scale, the impact is less likely to cause an airwave signal which can be detected instrumentally, or the estimation methods carry high uncertainty [e.g. 3, 4], hence, their mass is poorly constrained.
To assess the robustness of the energy estimation methods, we first collected meteoroid-derived measurements from the literature. We found that the radiation of the object is the most commonly measured property of the event [2]. Thus, the analysis focused on the optical energy signature of the objects. Most of the bolides did not have their total radiated energy estimated, hence, this was obtained based on the published light curve. Next, their kinetic energy was computed based on given estimates
of velocity and mass.
We derived an empirical relation between source energy and optical energy. We found a good correlation between entry kinetic energy and light radiation during deceleration, which holds regardless of fragmentation and ablation profiles.
The next step would be to extend this relation to more frequent, lower-energy impactors, and use it to calibrate complementary equipment (e.g. radiometers [5] or lightning mappers), to constrain size-frequency distribution of atmospheric impacts.
References
[1] F. Colas, et al., FRIPON: a worldwide network to track incoming meteoroids, Astronomy & Astrophysics 644 (2020) A53.
[2] S. Anghel, et al., Energy signature of ton TNT-class impacts: analysis of the 2018 December 22 fireball over Western Pyrenees, Monthly Notices of the Royal Astronomical Society 508 (2021) 5716.
[3] W. N. Edwards, et al., Estimate of the radiative power of bolides based on optical and infrasonic records, Journal of Atmospheric and Solar-Terrestrial Physics 68 (2006) 1136.
[4] T. A. Ens, et al., Infrasound production by bolides: A global statistical study, Journal of Atmospheric and Solar-Terrestrial
Physics 80 (2012) 208.
[5] J. L. Rault, F. Colas, Radiometry of meteors, arXiv 1911 (2019) 04290