‘Dent’ in earth’s magnetic field slowly expanding

Adent in Earth’s magnetic field over South America and the southern Atlantic Ocean is expanding westward and continuing to weaken in intensity, according to recent observations by NASA scientists. Currently, the dent has not created any visible impacts on daily life on Earth, but it could pose risk to satellites and spacecraft that pass through it, the US space agency said.

Earth’s magnetic field acts like a protective shield around the planet, repelling and trapping charged particles from the Sun.But over South America and the southern Atlantic Ocean, an unusually weak spot in the field – called the South Atlantic Anomaly, or SAA – allows these particles to dip closer to the surface than normal.

Particle radiation in this region can knock out onboard computers and interfere with the data collection of satellites that pass through it. Recent data shows the South Atlantic Anomaly's valley, or region of minimum field strength, has split into two lobes, creating additional challenges for satellite missions.

One study, led by NASA heliophysicist Ashley Greeley as part of her doctoral thesis, used two decades of data from SAMPEX to show that the anomaly is slowly but steadily drifting in a northwesterly direction.

“These particles are intimately associated with the magnetic field, which guides their motions,” said Shri Kanekal, a researcher in the Heliospheric Physics Laboratory at NASA Goddard Space Flight Center in Greenbelt, Maryland. Greeley’s results were also able to provide a clear picture of the type and amount of particle radiation satellites receive when passing through the South Atlantic Anomaly, which emphasised the need for continuing monitoring in the region.