Supersonic plasma jets detected for the first time in the Earth’s atmosphere

For the very first time, supersonic plasma jets reaching temperatures of 10,000°C have been detected in the ionosphere (earth’s upper atmosphere). This drastically changed its chemical composition.

The ionosphere is an atmospheric layer covering 75 to 1,000 kilometers above the Earth’s surface. A hundred years ago, Norwegian scientist Kristian Birkeland proposed the idea that vast electric currents powered by solar winds travel through this layer through the Earth’s magnetic field. Later, the first satellites sent into the upper atmosphere confirmed the existence of these currents: these are the “Birkeland currents”.

Birkeland currents are very powerful. These carry up to 1 TW of electrical power into the upper atmosphere, equivalent to one-third of the total energy consumption of the United States each year. They are also responsible for the aurora borealis and australis which sublimate the North and South poles. Eager to know more, the European Space Agency (ESA) sent in 2013 a trio of Swarm satellites into the space between the Earth’s ionosphere and the magnetosphere to investigate these famous Birkeland currents. They then discovered that these powerful electric fields could drive supersonic plasma jets: powerful electric currents that could reach 10,000°C. And inevitably, it is not without consequence.

 » These jets can indeed heat the ionosphere to temperatures close to 10,000°C, and therefore radically modify its chemical composition. says Bill Archer of the University of Calgary.  » They also carry currents from the ionosphere upwards, to higher altitudes where the extra excitation can cause material to be lost to space. « . The researchers also confirmed that these currents were stronger in the northern hemisphere and that they varied depending on the season (they are more intense in winter).

Since their launch in 2013, the Swarm satellites have been able to untangle the various magnetic signals that flow from the Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere. Swarm has been opening our eyes to the very complex functioning of our planet for four years now, from the heart to the highest atmospheric layers. And the more we “get to know” our planet, the more we will be able to understand and respond to its moods.


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