Strange hissing and whistling sounds that have been picked up 22 miles above Earth by a NASA student balloon have left the US space agency’s scientists baffled. The person who detected the sounds described the enigma like something from the X-Files.
Daniel Bowman, a doctoral student at the University of North Carolina at Chapel Hill, captured the sounds using infrared microphones aboard the balloon. Mr. Bowman also designed and built the equipment.
The sounds, which appeared at frequencies below 20 hertz, cannot be heard by human ears, unless the recordings are speeded up.
Daniel Bowman launching a NASA student balloon. (Image: geosci.unc.edu)
Infrasonic sound (low frequency sound) can travel very long distances and can be caused by natural phenomena including storms and earthquakes. However, in this case, scientists have no idea where they came from.
This is the first time these types of sounds have been captured so high up in our atmosphere, scientists say. NASA says it plans investigate further by sending more balloons.
What may have caused the weird sounds?
According to LiveScience, scientists have offered the following guesses to explain the eerie sounds:
– the signals came from a wind farm under the balloon’s flight path,
– ocean waves create low frequency sounds, they could have been the source,
– wind turbulence,
– the balloon cable vibrating could be the culprit,
– gravity waves, and
– clear air turbulence.
Mr. Bowman said to LiveScience:
“I was surprised by the sheer complexity of the signal. I expected to see a few little stripes.”
Video – Eerie infrasound recording