Detection of the Large Surface Explosion Coupling Experiment by a Sparse Network of Balloon-Borne Infrasound Sensors

In recent years, high-altitude infrasound sensing has become more prolific, demonstrating an enormous value especially when utilized over regions inaccessible to traditional ground-based sensing. Similar to ground-based infrasound detectors, airborne sensors take advantage of the fact that impulsive atmospheric events such as explosions can generate low frequency acoustic waves, also known as infrasound. Due to negligible attenuation, infrasonic waves can travel over long distances, and provide important clues about their source. Here, we report infrasound detections of the Apollo detonation that was carried on 29 October 2020 as part of the Large Surface Explosion Coupling Experiment in Nevada, USA. Infrasound sensors attached to solar hot air balloons floating in the stratosphere detected the signals generated by the explosion at distances 170-210 km. Three distinct arrival phases seen in the signals are indicative of multipathing caused by the small-scale perturbations in the atmosphere. We also found that the local acoustic environment at these altitudes is more complex than previously thought.

Automated summary

High-altitude infrasound sensing has become more common in recent years, especially in regions where traditional ground-based sensing is not feasible. Airborne sensors, similar to ground-based detectors, can detect low frequency acoustic waves generated by impulsive atmospheric events such as explosions. In this study, infrasound sensors attached to solar hot air balloons in the stratosphere detected signals from the Apollo detonation at distances of 170-210 km. The signals showed three distinct arrival phases, indicating multipathing caused by small-scale atmospheric perturbations. The study also revealed a more complex acoustic environment at these altitudes than previously believed.