Revisiting the Impact Energy Estimation of Well-Known Atmospheric Impacts

Introduction: Cosmic objects impact Earth's atmosphere on a daily basis, but due to their their small size, they often go unnoticed before atmospheric interaction. To better constrain impactor size and characteristics, we require calibrated multi-detector observations of meteoroid impacts. In a previous study, Anghel et al. (2021) [1] explored techniques for measuring pre-atmospheric mass of meteoroids with well-known trajectories at the source of ton TNT-scale impacts. This resulted in an empirical correspondence relation: log(E) = 0.72 · log(Eo) + (0.6 ± 0.5), where E represents the impact energy and Eo is the optical energy.

Methods: For the current analysis, we focused on an additional set of eight well-documented atmospheric impacts with meteorite recovery. We explore the full range of published results for each impact, including the data for Winchcombe (UK) [2], Saint-Pierre-le-Viger (France) [3], and Ribbeck (Germany) [4]. The bolides did not have their total radiated energy estimated, hence, this was obtained by digitizing the published light curve, and converting it into TNT equivalent. Next, their kinetic energy was computed based on the published estimates of velocity and mass.

Results & Conclusions: We found a very strong correlation between the object's kinetic energy at entry, and its light radiation during the entire deceleration, agreeing (within error) with the previous relation [1], regardless of fragmentation and ablation profiles (Fig 1). This consistency shows that calibrated light curves of atmospheric impacts provide a reliable energy and mass estimations across diverse meteoroid compositions and entry characteristics. 

Furthermore, this method can be enhanced with calibrated radiometers or extended to next-generation lightning mappers, whose relative luminosity measurements remain unaffected by cloud cover, ultimately helping to constrain the size-frequency distribution of impacts.

 

Acknowledgements: This work has received funding from the European Union’s Horizon Europe research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 101150536, for the project ”FLAME”.

References: [1] Anghel et al. (2021) Monthly Notices of the Royal Astronomical Society 508, 4, 5716-5733. [2] McMullan et al. (2024) Meteoritics & Planetary Science, 59, 5, 927-947. [3] Egal et al. (Accepted). [4] Spurný et al. (2024) Astronomy and Astrophysics, 686, A67.

 

Fig 1. The source energy vs radiated energy correspondence. The thick line represents a luminous efficiency of 100%. The red line represents the best fit line thorough the gray data, extracted from Anghel+21. The new data represents well-known bolides with independent energy estimations overlapped for comparison.