Using atmospheric impact data to model meteoroid close encounters

Abstract

ABSTRACT Based on telescopic observations of Jupiter-family comets (JFCs), there is predicted to be a paucity of objects at sub-kilometre sizes. However, several bright fireballs and some meteorites have been tenuously linked to the JFC population, showing metre-scale objects do exist in this region. In 2017, the Desert Fireball Network (DFN) observed a grazing fireball that redirected a meteoroid from an Apollo-type orbit to a JFC-like orbit. Using orbital data collected by the DFN, in this study, we have generated an artificial data set of close terrestrial encounters that come within 1.5 lunar distances (LD) of the Earth in the size-range of 0.01–100 kg. This range of objects is typically too small for telescopic surveys to detect, so using atmospheric impact flux data from fireball observations is currently one of the only ways to characterize these close encounters. Based on this model, we predict that within the considered size-range 2.5 × 108 objects ($0.1{{\ \rm per\ cent}}$ of the total flux) from asteroidal orbits (TJ > 3) are annually sent on to JFC-like orbits (2 < TJ < 3), with a steady-state population of about 8 × 1013 objects. Close encounters with the Earth provide another way to transfer material to the JFC region. Additionally, using our model, we found that approximately 1.96 × 107 objects are sent on to Aten-type orbits and ∼104 objects are ejected from the Solar system annually via a close encounter with the Earth.