An estimate of the terrestrial influx of large meteoroids from infrasonic measurements

Abstract

The influx rate of meteoroids hitting the Earth is most uncertain at sizes of ∼10 m. Here we make use of historical data of large bolides recorded infrasonically over a period of 13 years by the U.S. Air Force Technical Applications Center (AFTAC) to refine the terrestrial influx rate at these sizes. Several independent techniques were applied to these airwave data to calculate bolide kinetic energies. At low energies our flux results are within a factor of two in agreement with previous estimates. For 5–20‐m diameter objects, however, our measurements of the cumulative number of Earth‐impacting meteoroids are as much as an order of magnitude higher than estimates from telescopic surveys of near‐Earth objects and satellite‐detected bolides impacting the Earth. The precise cause of this disagreement is unclear, though we propose several possible explanations. From our infrasound study, our best estimate for the cumulative annual flux of impactors with energy equal to or greater than E (in kilotons of TNT equivalent) is N = 4.5 E−0.6.