A solar-powered balloon has just detected mysterious sounds in our atmosphere. More specifically, repetitive infrasound picked up from the side of the stratosphere. Researchers don’t know what it is…
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[EN VIDÉO] Stratobus, a stationary inflatable platform in the stratosphere. Certain missions transmitted by satellites (observation of an area on the ground, surveillance of fires…)
Our ears don’t hear everything that’s around us. Infrasound – low-frequency sounds – generated by things like earthquakes, volcanic eruptions, or even extreme weather events. Therefore, researchers have developed techniques to record them. To better understand how our earth works.
A team at Sandia Laboratories, one of the US Department of Energy’s main laboratories, has just made a startling discovery on the matter. During certain flights of their solar balloons, they recorded mysterious infrasound several times an hour. Infrasound, the origin of which is completely unknown.
Natural sounds, but also artificial sounds
This infrasound – sound with frequencies below 20 HzHz – has been detected in the stratosphere, a rather quiet layer of our atmosphere. Without turbulence and commercial air traffic. Thanks to microbarometers, originally developed to listen to volcanoes, researchers can even hear the sound of waves on the sea or the rumble of thunder. And, a little less naturally, the sound of rocket launches or rotating wind turbines.
To reach the stratosphere, the microbarometers are transported on board large balloons. With a diameter of 6 to 7 meters. Balloons for a maximum of 50 euros each, filled with charcoal dust. When the sun shines, the dust heats the air inside the balloons, and the whole thing rises to over 20 kilometers in the air. Now all they have to do is track their route with GPSGPS.
Coming back to those funny noises the researchers recorded, they could very well be pretty mundane. Areas with turbulence, violent storms or even freight trains. All possibly amplified and scrambled in some kind of conduit that carries sound long distances through the atmosphere. The investigation continues…