Scientists at NASA are closely monitoring a vast region of weakened magnetic intensity—known as the South Atlantic Anomaly (SAA)—due to the unique challenges it poses for satellites.
From South America to southwest Africa, the SAA has been likened to a “dent” in Earth’s magnetic field or a “pothole in space” by the premier space agency. The phenomenon has intrigued and concerned scientists for years.
While it has little impact on life on Earth, the same cannot be said for orbital spacecraft, including the International Space Station, which passes directly through this anomaly in low-Earth orbit.
Scientists fear the weakening magnetic intensity inside the anomaly could malfunction or lead to short circuits in technological systems onboard satellites if they get struck by high-energy protons from the sun.
A growing concern for satellites
Though these hits may produce only low-level glitches, they could lead to significant data loss or even permanent damage to key components, forcing the satellite operators to shut down systems before spacecraft enter the anomaly zone routinely.
Yet, beyond the risks, researchers see the SAA as a valuable opportunity to probe the complexities of Earth’s magnetic field. “The magnetic field is actually a superposition of fields from many current sources,” explained geophysicist Terry Sabaka from NASA’s Goddard Space Flight Center in 2020.
“The magnetic field is a superposition of fields from many current sources,” geophysicist Terry Sabaka from NASA’s Goddard Space Flight Centre in Greenbelt, Maryland, said while explaining the phenomenon in 2020.
Scientists suggest that the anomaly may originate from the turbulent flow of molten iron in Earth’s outer core, deep beneath the surface. This churning motion generates electrical currents that shape the planet’s magnetic field—though not always in a perfectly uniform manner.
Situated roughly 2,900 kilometers (1,800 miles) beneath the African continent, a massive reservoir of dense rock—known as the African Large Low Shear Velocity Province—is believed to disrupt Earth’s magnetic field formation.
Credits: NASA’s Goddard Space Flight Center
This disturbance, combined with the tilt of the planet’s magnetic axis, contributes to the significant weakening observed in the region.
In 2020, NASA Goddard geophysicist and mathematician Weijia Kuang suggested that the South Atlantic Anomaly (SAA) could result from the weakening dominance of the dipole field in the region.
He explained that a localized field with reversed polarity appears to strengthen within the anomaly, significantly reducing the overall magnetic intensity compared to surrounding areas.
However, scientists are far from unraveling the mystery behind SAA and its implications. However, recent studies are providing fresh insights into this vast phenomenon.
A shifting, evolving mystery
Recent studies reveal that the SAA is not static. A 2016 study led by NASA heliophysicist Ashley Greeley found that the anomaly gradually drifts—a finding later confirmed by CubeSat tracking in 2021.
But the movement is not its only peculiarity. In 2020, scientists discovered that the anomaly appears to split into two regions of minimum magnetic intensity, suggesting a more complex evolution than previously thought.
While its future implications remain unclear, evidence suggests the anomaly is not recent.
A study published in July 2020 indicated that similar magnetic disturbances may have occurred as far back as 11 million years ago, suggesting the SAA is not necessarily a precursor to a full-scale planetary magnetic field reversal—an event that occurs but only over hundreds of thousands of years.
More recently, a 2024 study revealed that the anomaly also influences auroras on Earth. With so many unanswered questions, continued observation is crucial.
As NASA scientist Terry Sabaka emphasized, the SAA changes over time, making ongoing monitoring essential for refining models and predictions.