Modeling the measurement accuracy of pre-atmosphere velocities of meteoroids

TL;DR

This paper investigates the discrepancy between pre-atmosphere meteoroid velocities and observed velocities at detection, revealing significant underestimations that affect orbit calculations, using numerical ablation models validated against observational data.

Contribution

It introduces a numerical model to quantify pre-atmosphere velocities and demonstrates the impact of neglecting early deceleration on meteoroid orbit estimations.

Findings

Most low-velocity meteoroids have velocity underestimations of 100-750 m/s.

Neglecting early deceleration leads to systematically lower orbit semi-major axes.

Model validation shows good agreement with observed luminous beginning heights.

Abstract

Many existing optical meteor trajectory estimation methods use the approximation that the velocity of the meteor at the beginning of its luminous phase is equivalent to its velocity before atmospheric entry. Meteoroid kinetic energy loss prior to the luminous phase cannot be measured, but for some masses and entry geometries neglecting this loss may lead to non-negligible deceleration prior to thermal ablation. Using a numerical meteoroid ablation model, we simulate the kinematics of meteoroids beginning at 180 km with initial velocities ranging from 11 km/s to 71 km/s, and compare model velocities at the moment of detection to measurements. We validate the simulations by comparing the simulated luminous beginning heights with observed beginning heights of different populations of meteors detected with different optical systems. We find that most low-velocity meteoroids have a significant velocity difference of 100 m/s to 750 m/s (depending on meteoroid type, mass, and observation system). This systematic underestimate of meteoroid speeds also results in systematically lower semi-major axes for meteoroid orbits.