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On August 30, 2012, NASA launched the Van Allen Probes into orbit in near-Earth space to study the donut-shaped radiation belts for which they were named.  The goal of the mission was to gather data from within the Van Allen belts to further the understanding of these rings of highly charged particles that shield the Earth’s atmosphere from the ravages of solar radiation while also damaging communications satellites.  These space probes were disabled in 2019 and will re-enter the Earth’s atmosphere in 2034.  

EMFISIS, the Electric and Magnetic Field Instrument Suite and Integrated Science, was placed aboard each of the Van Allen probes collect data about electric and magnetic waves in the Earth’s orbit.   Two main sensors, a fluxgate magnetometer (MAG) and a magnetic search coil magnetometer (MSC), measured the energies the spacecraft encountered within a frequency range of 10 Hz to 400 kHz. This waveform data was then shifted into the range of human hearing to create sounds representative of the movement of energy particles within the Van Allen radiation belt.  The two distinctive sounds that have been observed across multiple data sets have been dubbed “whistlers” and “chorus”.

What is so interesting about these sounds, created by fluctuating magnetics and electric fields, is that they are not unknown to us.  Similar energetic effects can be observed here on Earth.  VLF radio field recordings of the Earth’s magnetic field have captured the birdlike chirp referred to as “chorus”.   Electromagnetic energy dispersed by lightning strikes creates a similar sounding effect to the “whistlers” measured in the Van Allen Belt, via its disruption of radio waves within the Earth’s ionosphere, and has been documented by HAM radio operators for decades.   What we have been hearing on Earth, however, are the echoes energized particles inhabiting the magnetic fields ringing our planet.  With the publication of the data from the Van Allen probes we have the opportunity to listen to these events captured at the source, in full 16-bit glory.

All sounds are from data published by the EMFISIS team, Department of Physics at the University of Iowa

Video is a NASA simulation based on data collected by the Van Allen Probes of the effects of a solar storm that took place March 17 2015.


Broadcast date: June 27, 2021
KCHUNG Los Angeles 1630AM

SPECIAL COLLECTIONS is a broadcast project by Sam Rowell.
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