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A growing weak spot in the magnetic field surrounding the Earth could lead to satellite malfunction and even cause them to undergo full blackouts, scientists warned in a new study.
The Earth’s complex and dynamic magnetic field is vital to the survival of all life, protecting the planet from cosmic radiation and charged particles from the Sun.
It is generated by a global ocean of molten liquid iron, which makes up the Earth’s outer core about 3000km beneath our feet.
Like a bicycle dynamo, this spinning ocean of iron creates electrical currents, which in turn, generates the planet’s protective electromagnetic field.
But the exact processes generating the magnetic field is far more complex and remains to be thoroughly studied.
For instance, in the southern hemisphere the magnetic field is particularly strong at one point, and in the northern hemisphere there are two such points – one around Canada and the other around Siberia.
Scientists are gaining more insights into the planet’s magnetism thanks to data from a constellation of three identical satellites launched in 2013 that measure the magnetic signals separately from Earth’s core, mantle, crust and oceans as well as the planet’s outer atmosphere layers.
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Satellite swarm (ESA)
Now, after tracking 11 years of magnetic field measurements from this satellite constellation, researchers have discovered that the weak region in Earth’s magnetic field over the South Atlantic – known as the South Atlantic Anomaly.
This weak spot has also expanded by an area nearly half the size of continental Europe since 2014, according to a new study published in the journal Physics of the Earth and Planetary Interiors.
“The South Atlantic Anomaly is not just a single block. It’s changing differently towards Africa than it is near South America. There’s something special happening in this region that is causing the field to weaken in a more intense way,” says Chris Finlay, lead author of the study from the Technical University of Denmark.
Researchers link this distortion of the Earth’s magnetic field to strange patterns in the boundary between Earth’s liquid outer core and its rocky mantle.
“Normally we’d expect to see magnetic field lines coming out of the core in the southern hemisphere, but beneath the South Atlantic Anomaly we see unexpected areas where the magnetic field, instead of coming out of the core, goes back into the core,” Dr Finlay explains.
“Thanks to the Swarm data we can see one of these areas moving westward over Africa, which contributes to the weakening of the South Atlantic Anomaly in this region,” he said.
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South Atlantic anomaly (ESA)
Latest satelite data suggests the magnetic field over Siberia has strengthened, while it has weakened over Canada.
This shift is important for satellite navigation systems, which are affected by the dance between these two areas of strong magnetic field, scientists say.
It can be a major factor in determining the radiation dose experienced by low Earth orbit satellites, they warn.
Researchers caution that spacecraft and spacefarers, including those aboard the International Space Station, that enter the South Atlantic weak spot could now be exposed to more radiation.
