The 'alien sounds' captured 22 MILES above Earth: Nasa recording from the edge of space has unexplained hisses and whistles
- Special microphones picked up infrasounds at frequencies below 20 hertz
- Theories range from gravity waves to wind farms and clear air turbulence
- Nasa still can't explain noises and will launch another study later this year
Mysterious 'infrasounds' have been captured from the edge of space for the first time in 50 years.
The sounds were recorded aboard a Nasa student balloon experiment using infrared microphones.
The recording features unexplained hisses and whistles heard 22 miles (36km) above the Earth's surface.
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Mysterious 'infrasounds' have been captured from the edge of space for the first time in 50 years. The sounds were recorded aboard a Nasa student balloon experiment using infrared microphones
WHAT ARE INFRASOUNDS?
Infrasound are sound waves at frequencies below 20 hertz.
Sounds at those frequencies are inaudible to the human ear.
An important characteristic of infrasonic sound is that it travels long distances. Natural phenomenon such as storms and earthquakes can produce infrasonic sounds.
They were captured by Daniel Bowman, a student at the University of North Carolina at Chapel Hill, according to a report in LiveScience.
He was able to pick up sound waves at frequencies below 20 hertz, which can only be heard by human ears by speeding up recordings.
'It sounds kind of like The X-Files,' Bowman told Live Science.
An important characteristic of infrasonic sound is that it travels long distances.
While natural phenomenon such as storms and earthquakes can cause infrasounds, researchers still don't know what was picked up in these recordings.
To capture the noises, Bowman released the infrared microphones on a helium balloon above New Mexico and Arizona in August as part of the High Altitude Student Platform (HASP) study.
The balloon floated 450 miles (725 km) across the Earth's surface and reached a height of more than 123,000ft (37,500 metres).
Students at the University of North Carolina at Chapel Hill released the infrared microphones on a helium balloon above New Mexico and Arizona in August as part of the High Altitude Student Platform (HASP) study
This is the first time an infrasound study has reached these heights.
Theories for the sounds range from a wind farm under the balloon's path, to ocean waves, gravity waves and clear air turbulence.
Nasa now plans to send another payload to record more of these strange noises later this year
Others suggest the noises may be coming from movements from the balloon cable.
A Nasa-backed project now plans to send another payload to record more of these strange noises later this year.
'There haven't been acoustic recordings in the stratosphere for 50 years,' Bowman told LiveScience.
'Surely, if we place instruments up there, we will find things we haven't seen before,' he said.
While these sounds from space are unexplained, Esa has been putting together a collection of more familiar noises from the cosmos in a soundcloud.
The amazing collection of clips include some that have been artificially amplified to be audible to humans, and others that are simply as they originally sounded.
The various noises from space are shared on Esa's esaops Soundcloud page.
One clip uses audio data collected by the Huygens probe as it descended onto the surface of Saturn's moon Titan on 14 January 2005.
The spacecraft carried with it acoustic sensors on the Huygens Atmospheric Structure Instrument (Hasi), which recorded the surroundings as the probe descended.
According to Esa they ‘give a realistic reproduction of what a traveller on board Huygens would have heard during one minute of the descent through Titan's atmosphere.’