NASA balloon captured 'alien sounds' from the edge of space

A student experiment revealed strange sounds of unknown origin.
By Kathy Fey | May 07, 2015
A NASA balloon experiment picked up odd sounds while floating 22 miles above the Earth. The balloon carried infrasound microphones capable of recording sound waves in the atmosphere at frequencies below 20 hertz. In order to be audible to humans, the recordings were sped up into human hearing frequency range.

According to LiveScience, a student from the University of North Carolina named Daniel Bowman designed and built the equipment. The balloon captured the sounds while flying over Arizona and New Mexico as part of a student program run by NASA and the Louisiana Space Consortium. The experiment that captured the sounds was one of ten flown from the High Altitude Student Platform. Since 2006, the program has launched over 70 student experiments.

The balloon flew for 9 hours, reaching a height of over 37,500 meters above Earth, which is higher than airplanes fly but lower than the very top of the stratosphere. The balloon's flight marked the highest point to which infrasound equipment has ever been carried.

The sounds picked up by the instrument puzzled scientists. Researchers working to decipher the recordings claimed they had never encountered such signals before. "It sounds kind of like 'The X-Files,'" Bowman said. Some possibilities for the source of the sounds include a wind farm, crashing ocean waves, atmospheric turbulence, gravity waves, and vibrations created by the balloon cable.

Referring to the visual representation of the sounds via spectrogram, Bowman said, "I was surprised by the sheer complexity of the signal. I expected to see a few little stripes."

Infrasound carries for great distances, and is typically created by low-frequency wave-creating events like earthquakes, volcanoes, thunderstorms and meteors. As infrasound detectors can be used to monitor weather and geologic activity, scientists have considered including infrasound detectors in future Mars missions.

Bowman hopes this recent infrasound experiment will spark more interest in the subject. "There haven't been acoustic recordings in the stratosphere for 50 years. Surely, if we place instruments up there, we will find things we haven't seen before,"he said.

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