Mysterious sounds recorded at Earth’s stratosphere leaves scientists puzzled - WION

Scientists have detected a “strange” sound of “completely unknown origin” from Earther’s upper atmosphere —the stratosphere.

The sound was recorded by large 6-7-metre-long solar balloons carrying a microphone that was sent by a team of researchers from Sandia National Laboratories, US.

The stratosphere region— found around 31 miles (50 km) above the planet—is relatively calm and free of storms, turbulence and commercial air traffic.

But the scientists were left baffled when they heard through the microphone mysterious sounds that are said to have been repeated a few times per hour.

The sounds recorded were in the infrasound range, which is at the frequency range of 20 hertz (Hz) and lower, and well below the range of the human ears. The source is yet to be identified.

"There are mysterious infrasound signals that occur a few times per hour on some flights, but the source of these is completely unknown," Daniel Bowman of Sandia National Laboratories said in a statement.

The research team used a sound gathering device called microbarometers that are capable of detecting detect low-frequency sounds. It was initially designed to monitor volcanoes.

These sensors were carried aloft by balloons that the researchers built from common and inexpensive materials.

These solar balloons are powered by sunlight and have the capability to climb to altitudes of around 70,000 feet (13.3 miles) over Earth. 

After the launch, the balloons were tracked using GPS, because they can often fly for hundreds of kilometres and may land in difficult terrains of the planet posing a challenge to locate it.

"Our balloons are basically giant plastic bags with some charcoal dust on the inside to make them dark," Bowman was quoted as saying by the CNN.

"We build them using painter's plastic from the hardware store, shipping tape, and charcoal powder from pyrotechnic supply stores. When the sun shines on the dark balloons, the air inside heats up and becomes buoyant."

Though the solar balloons offer greater access to record noise levels at lower frequency ranges since the whole Earth is accessible, they also present challenges for researchers. The stratosphere is a harsh environment with wild temperature fluctuations between heat and cold.

“Solar balloons are a bit sluggish, and we’ve wrecked a few on bushes when trying to launch them,” Bowman said.

“We’ve had to hike down into canyons and across mountains to get our payloads. Once, our Oklahoma State colleagues actually had a balloon land in a field, spend the night, and launch itself back in the air to fly another whole day!”

(With inputs from agencies)

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https://news.google.com/rss/articles/CBMicmh0dHBzOi8vd3d3Lndpb25ld3MuY29tL3NjaWVuY2UvbXlzdGVyaW91cy1zb3VuZHMtcmVjb3JkZWQtYXQtZWFydGhzLXN0cmF0b3NwaGVyZS1sZWF2ZXMtc2NpZW50aXN0cy1wdXp6bGVkLTU5MTU0M9IBdmh0dHBzOi8vd3d3Lndpb25ld3MuY29tL3NjaWVuY2UvbXlzdGVyaW91cy1zb3VuZHMtcmVjb3JkZWQtYXQtZWFydGhzLXN0cmF0b3NwaGVyZS1sZWF2ZXMtc2NpZW50aXN0cy1wdXp6bGVkLTU5MTU0My9hbXA?oc=5

2023-05-12 06:08:13Z
2022241616