Where Did They Come From, Where Did They Go. Grazing Fireballs

TL;DR

This paper details the observation and analysis of a rare grazing fireball event captured by the Desert Fireball Network, revealing its origin from an Apollo-type orbit and its future orbital evolution.

Contribution

It provides the first detailed trajectory and origin analysis of a grazing fireball, including its deep atmospheric penetration and orbital transition due to Earth's gravitational influence.

Findings

The fireball lasted over 90 seconds and traveled 1,300 km.

It originated from an Apollo-type orbit and transitioned to a Jupiter-family comet orbit.

The meteoroid's initial mass was estimated at at least 60 kg.

Abstract

For centuries extremely-long grazing fireball displays have fascinated observers and inspired people to ponder about their origins. The Desert Fireball Network (DFN) is the largest single fireball network in the world, covering about one third of Australian skies. This expansive size has enabled us to capture a majority of the atmospheric trajectory of a spectacular grazing event that lasted over90 seconds, penetrated as deep as ~58.5km, and traveled over 1,300 km through the atmosphere before exiting back into interplanetary space. Based on our triangulation and dynamic analyses of the event, we have estimated the initial mass to be at least 60 kg, which would correspond to a30 cm object given a chondritic density (3500 kg m-3). However, this initial mass estimate is likely a lower bound, considering the minimal deceleration observed in the luminous phase. The most intriguing quality of this close encounter is that the meteoroid originated from an Apollo-type orbit and was inserted into a Jupiter-family comet (JFC) orbit due to the net energy gained during the close encounter with the Earth. Based on numerical simulations, the meteoroid will likely spend ~200kyrs on a JFC orbit and have numerous encounters with Jupiter, the first of which will occur in January-March 2025. Eventually the meteoroid will likely be ejected from the Solar System or be flung into a trans-Neptunian orbit.