A novel methodology to estimate pre-atmospheric dynamical conditions of small meteoroids

Abstract

Recent observations using the Wind and Ulysses spacecrafts and the Solar Occultation For Ice Experiment (SOFIE) during the period between 2007 and 2020 indicate a total cosmic dust influx at Earth ranging from 22 to 32 tonnes per day. Much is still unclear about the formation, evolution, and propagation of this cosmic dust throughout our Solar System, as well as the transport and chemical interaction of such particles within our own atmosphere. Studying meteoroids, which are particles small and fast enough to ablate in the Earth’s upper atmosphere producing meteor plasma detectable by meteor radars, offers an opportunity to better understand these processes. While meteor radars provide a powerful tool to detect meteoroids, they are limited to detecting particles that produce a sufficient amount of plasma within the instrument’s field-of-view, and thus most of their trajectory remains undetected. In this work, we report a novel methodology, using new polarization measurements as well as two state-of-the art models, to determine the pre-atmosphere dynamical characteristics of the detected particles, before they suffer any significant ablation or deceleration. We present the results for 20 meteor detection case studies, and find that for the majority of particles, at least 80% (typically 95%) of the particle mass has already been lost at the time of detection. In addition, while all particles experienced deceleration by the time of detection, this was typically small (≤4% of their initial velocity). Future work will implement this new methodology to automatically determine the initial mass and velocities of individual meteors. This will help provide more precise meteor orbits and characterization of parent source populations, as well as the identification of potential interstellar particles.