Dynamic Trajectory Analysis of Meteoroids Showing Minimal Deceleration

Abstract

Meteoroids decelerate and ablate as they descend through the atmosphere, however a portion of instrumentally observed meteors show little measurable deceleration and remain poorly characterised. These are referred to as minimally decelerating objects (MDOs). The traditional alpha-beta method of dynamic trajectory analysis cannot reliably determine their preatmospheric masses or rates of ablation. We present a new approach for estimating the ballistic coefficients (alpha) and mass loss parameters (beta) of MDOs, allowing their inclusion in dynamic analyses. This new method employs bulk ablation coefficients derived from instrumentally observed meteorite falls and large meteor shower bodies. It is applied to MDOs comprising approximately one-third of the Global Fireball Observatory (GFO) 2014 - 2024 dataset. Our results show that MDOs are predominantly small objects occupying a distinct region of alpha-beta space. Material types can be identified using supplementary data such as emission spectra, which we demonstrate using observations of 10 small iron meteoroids. This methodology expands the range of meteoroid populations accessible to dynamic trajectory analysis, providing new constraints on meteorite deposition and the compositional diversity of near-Earth objects.