NASA listens in as electrons whistle while they work

July 17, 2017 by Mara Johnson-Groh
Space is not empty, nor is it silent. The region around Earth is filled with magnetic field lines and trapped energetic particles, zooming about in a high-speed dance around the planet (shown here in an illustration). Credit: NASA's Goddard Space Flight Center/Brian Monroe

Space is not empty, nor is it silent. While technically a vacuum, space nonetheless contains energetic charged particles, governed by magnetic and electric fields, and it behaves unlike anything we experience on Earth. In regions laced with magnetic fields, such as the space environment surrounding our planet, particles are continually tossed to and fro by the motion of various electromagnetic waves known as plasma waves. These plasma waves, like the roaring ocean surf, create a rhythmic cacophony that—with the right tools—we can hear across space.

Just as roll across the ocean or storm fronts move through the atmosphere, disturbances in space, can cause waves. These waves occur as fluctuating electric and magnetic fields plow through clumps of ions and electrons that compose the plasma, pushing some to accelerated speeds. This interaction controls the balance of highly energetic particles injected and lost from in the near-Earth environment.

One type of plasma wave fundamental to shaping our near-Earth environment are whistler-mode waves. These waves create distinct sounds dependent on the plasma they travel through. For example, the region tight around Earth, called the plasmasphere, is relatively dense with cold plasma. Waves traveling inside this region sound much different than those outside. While different whistler-mode waves sing different sounds, they all move in the same way, with the same electromagnetic properties.

When lighting strikes the ground, the electrical discharge can also trigger whistler-mode plasma waves. Some of the waves escape beyond the atmosphere to bounce like bumper cars along Earth's lines between the north and south poles. Since the lightning creates a range of frequencies, and since higher frequencies travel faster, the wave howls a falling pitch, giving the wave its name—a whistler.

Different types of plasma waves triggered by various mechanisms, occupy different regions of space around Earth. Credit: NASA's Goddard Space Flight Center/Mary Pat Hrybyk-Keith

Out beyond the plasmasphere, where the plasma is tenuous and relatively warm, whistler-mode waves create primarily rising chirps, like a flock of noisy birds. This type of wave is called chorus and is created when electrons are pushed towards the night side of Earth—which in some cases, may be caused by magnetic reconnection, a dynamic explosion of tangled on the dark side of Earth. When these low energy electrons hit the plasma, they interact with particles in the plasma, imparting their energy and creating a unique rising tone.

Whistler-mode waves traveling inside the plasmasphere are called plasmaspheric hiss and sound a lot like radio station static. Some scientists think hiss is also caused by lightning strikes, but others think it could be caused by chorus waves that have leaked inside the plasmasphere. Both chorus and hiss waves are key shapers of the near-Earth environment including the Van Allen radiation belts, doughnut-shaped rings of high-energy particles encircling the planet.

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A type of plasma wave known as chorus as heard by the EMFISIS instrument aboard NASA’s Van Allen Probes as it passed around Earth. Credit: NASA/University of Iowa

NASA scientists, with the help of the Van Allen Probes mission, are working to understand the dynamics of waves to improve predictions of space weather, which can have damaging effects on satellites and telecommunications signals. As a part of their observations, the scientists have recorded these eerie sounds made by different in the particle symphony surrounding Earth.

NASA's two Van Allen Probe spacecraft use an instrument called EMFISIS, short for Electric and Magnetic Field Instrument Suite and Integrated Science, to measure electric and magnetic waves as they circle Earth. As the spacecraft encounter a wave, sensors record the changes in the frequency of the electric and magnetic fields. The scientists shift the frequencies to the audible range so that we can listen to the sounds of space.

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Whistler waves as heard by the EMFISIS instrument aboard NASA’s Van Allen Probes as it passed around Earth. Credits: NASA/University of Iowa

By understanding how waves and interact, scientists can learn how electrons are accelerated and lost from the radiation belts and help protect our satellites and telecommunications in .

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Chorus waves as heard by the EMFISIS instrument aboard NASA’s Van Allen Probes as it passed around Earth. Credits: NASA/University of Iowa

Explore further: Making waves with the hot electrons within Earth's radiation belts

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9 comments

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Chris_Reeve
2 / 5 (4) Jul 17, 2017
It's interesting that the author managed to avoid a single usage of the term "double layer" in an article entirely dedicated to plasmas generating noises.
Hyperfuzzy
not rated yet Jul 17, 2017
You are only looking upon the wrinkles in field and the motion of field centers. All of space, at each point, is the summation of the fields of every charge in the universe, i.e. the field due to each charge or each charge as its field!

I would learn to surf, or ski, or control a charge distribution such that it accelerates through this sea. We got more to do just listening to the silence!

Note: Charge is its center and its field, at the center is only the field. When a charge oscillates, its field wrinkles as per Maxwell. The relative speed of these wrinkles, or the speed of light is the original wavelength divided by the measured period.
Hyperfuzzy
not rated yet Jul 17, 2017
Empty space cannot exist. Charge, apparently never created or destroyed, its field, or the charge, extends from its center to infinity.
Captain Stumpy
4.2 / 5 (5) Jul 17, 2017
@idiot eu pseudoscience cult peon chris/hannes
It's interesting that the author managed to avoid a single usage of the term "double layer"...
have you tried asking why?

no... that would be far, far too easy a solution
it is also demonstrably dead set against eu policy to actually deal in verifiable facts

given your extreme veneration of the eu idol Alfven, lets talk about experience, lab results and things that can be measured:

Mara Johnson-Groh of the Department of Physics and Astronomy, University of Victoria has: 40+ published papers with a trend (plasma physics) that are based on experiment

chris reeve has: a blog where he whinges on about the treatment his eu cult gets while attempting to show where there is some grand conspiracy against his cult using historical non-relevant anecdotal stories that don't apply to reality

who should we consider the more reputable in this case?
considering her material is published and able to be verified
vrs his zilch....
Hyperfuzzy
1 / 5 (1) Jul 17, 2017
Listening is one thing, frequency down shifting creates very interesting audio. It gives one an audible field for the waves, i.e. the audible time varying frequency and amplitude, it's almost as if on can field actions of the sea within the space-time about the planet.
andyf
5 / 5 (2) Jul 17, 2017
Hyper, are you sure you're not a chat-bot?
Captain Stumpy
5 / 5 (2) Jul 18, 2017
@idiot eu pseudoscience cult peon chris/hannes

awww! you downrated me!
boohoo

i thought you were a researcher seeking to find truth and expose the problems of modern science?

does the logic of the point sting as it penetrates your delusion?

i mean, you keep alluding to the failure of the modern scientists so... where is the correction published from the eu cult of pseudoscience idiots?

where is the study that explains it all with experiments and validation?

this is logic 101 - basic sh*t here

you have been arguing for years about how modern scientists fail and that only you and your cult of eu idiots can help expose the problem using historical examples which don't apply to modern reality

you keep arguing that they don't learn these historical examples (even though i proved that wrong with evidence)

every argument you've made typically ends up argument from authority (usually irrelevant)
they have it in spades
you don't

next?
Hyperfuzzy
not rated yet Jul 18, 2017
Hyper, are you sure you're not a chat-bot?

Before I give an answer, answer this, "Is their intelligent life on planet earth?" Better stated, "Is the idea of an intelligent humanity whimsical!?"
cantdrive85
1 / 5 (3) Jul 18, 2017
Is their intelligent life on planet earth?" Better stated, "Is the idea of an intelligent humanity whimsical!?"

If Cap'n Stoopid is the proxy, then the answers are no and yes, respectively

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