Infrasound Detection of Meteoroids

Abstract

As fragments floating through space, asteroids contain a lot of information regarding the history and development of our universe. As such, for a long time humans have been fascinated by meteor entries into the atmosphere, and have devised large scale camera networks to track the entries of such meteors. Despite the effort put into these camera networks, this approach to detecting meteors has serious limitations regarding its effectiveness during daytime or during cloudy nights as this prevents the fireballs from being visible. As such, there is interest in expanding these detection networks with infrasound sensors, highly sensitive microphones which can detect the low frequency sound that propagates from a meteoric entry shockwave.A lot is still unknown regarding the effective implementation of such infrasound sensors into a detection network. As such, this study investigates three important aspects of such a potential implementation, being the detection pipeline/algorithm, methods for reducing the wind noise, and the layout of a potential future network.Using publicly available infrasound data and meteor detections, a pipeline was developed for detecting meteoric entry signatures in this data. Although some likely meteor signatures were found within this data, the true detection rate is only around 3%-4% of the events included in this analysis, with a similar number of false positive detections being flagged.To achieve better detections in a properly integrated network, two different approaches have been tested for reducing wind noise at the infrasound sensor. Both the tested porous hose filter and the fabric dome filter successfully reduced the measured noise level by $10$ to $15$ dB between $10$ and $30$ Hz. At slightly higher frequencies, the porous hose filter started to perform worse as a filter, and began introducing artifacts into even coherent signals.Lastly, the layout of a potential infrasound network within the Netherlands has been investigated. For this network, three infrasound sensors would be placed throughout the Netherlands, with stations guaranteed at Delft University of Technology and Tilburg, and a third sensor at a yet undetermined location. From the available candidate locations, the Elburg location was found to provide the most versatile detection network for future research into infrasound detection of meteors.