Solar-Powered Balloons Detect Strange Noises

Picture of the atmosphere | Image by Chaleephoto, Shutterstock

Scientists are making discoveries in the earth’s upper atmosphere.

Researchers released solar-powered balloons into the stratosphere and discovered strange sounds emanating above our planets with no known origin.

The stratosphere is the second layer of the atmosphere and extends from just over 6 miles to an altitude of about 31 miles. While commercial aircraft do not fly at this altitude, weather balloons, spy planes, and the ozone layer are all found at this height.

The United Corporation for Atmospheric Research reported that air in that layer is about 1,000 times thinner at the upper edge of the stratosphere than at sea level.

Principal Scientist Daniel Bowman of Sandia National Laboratories and his team released balloons spanning 19 to 22 feet into the stratosphere to document sounds in this layer. Bowman said in a news release that his team made the balloons from rudimentary materials such as painter’s plastic, shipping tape, and charcoal powder.

“When the sun shines on the dark balloons, the air inside heats up and becomes buoyant. This passive solar power is enough to bring the balloons from the surface to over 20 km (66,000 ft) in the sky,” Bowman added. “Each balloon only needs about $50 worth of materials and can be built in a basketball court.”

Bowman presented this research at the 184th Meeting of the Acoustical Society of America in Chicago on Thursday.

Bowman and his team sent these devices up to 70,000 feet, or just over 13 miles, into the air. The researchers then used microbarometers to collect data and observe low-frequency sounds and tracked the location of the balloons using GPS.

Researchers documented not only natural and man-made sounds but also observed sounds that appear to have no known origin.

“[In the stratosphere], there are mysterious infrasound signals that occur a few times per hour on some flights, but the source of these is completely unknown,” said Bowman in the press release.

According to PubMed, infrasound is an audible frequency that ranges from “very low-frequency atmospheric fluctuations up into the lower audio frequencies.” The National Library of Medicine reported that this sound can be traced to “low-speed machinery, natural causes, and industrial installations.”

While these scientists have not determined the source of the sounds, they are hopeful that these balloons could aid in researching the planet Venus and observing its geological processes through its cloud cover.

“I’ve been doing it for about 10 years now, and, you know, the fact that there’s mysterious sounds that I don’t understand is troubling, but it’s not like a revelation,” said Bowman, according to the Washington Post.

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