Researchers show that bolides – meteoroids that explode in the atmosphere – create sound waves that can be analyzed for warning purposes about space debris and other astronomical threats
Earth is constantly gaining mass from space: cosmic dust, meteorites, and even bits of space junk that fall from the sky. Scientists are now investigating how to better track mysterious “skyrockets” – known as bullies – Using global infrasound sensors, which are able to hear the echoes of deep sound waves in the sky.
A faint sound from space that helps locate incoming fragments
Every year, the Earth adds thousands of tons of space dust and about 50 tons of meteorites. Since the 60s, discarded space equipment has also occasionally entered the atmosphere: parts of launchers, instruments lost during spacewalks, defunct satellites, and other objects moving in low-Earth orbit at a speed of about 29,000 kilometers per hour.
When one of these objects—natural or man-made—enters the atmosphere, scientists track its trajectory to predict where it will fall. Will it plunge straight down, or move at some angle before hitting the ground?
How Bolides Create a Unique Analysis Challenge
At the European Union's General Conference on Earth Sciences, Elizabeth Silver of Sandia Laboratories presented research on using infrasound sensors to monitor meteoroids—intense flashes of light and supersonic booms that occur when large meteoroids disintegrate high in the atmosphere. The explosion releases a lot of energy, creating shock waves that travel as infrasound waves for thousands of kilometers.
But unlike a point explosion, a bolide produces sound along its entire path through the atmosphere, especially when it enters at a flat angle. This makes it difficult to determine its exact location, as different sensors may pick up the sound from different points along the path.
The importance of the angle in the bolide's trajectory
Silver used the Treaty on the Non-Proliferation of Nuclear Tests (CTBTO)’s global network of infrasound sensors, which listens for both nuclear explosions and thunder, supersonic aircraft – and bolides. She found that when a bolide enters at a sharp angle (above 60°), its trajectory is easier to determine. But at a shallower angle, the uncertainty increases.
“Infrasound from a bolide is more like a supersonic boom stretching across the sky than a single explosion,” Silver explained. “You have to consider that the sound is created along its flight path.”
Conclusion: We must understand the route
Silver's conclusion: It's important to incorporate the object's trajectory when interpreting infrasound data. Infrasound sensors are essential tools for planetary defense—whether it's meteoroids or space debris.
“If you don’t know where something is going, it’s hard for you to prepare for it,” she concluded.
More of the topic in Hayadan:
