NASA researchers are closely monitoring the South Atlantic Anomaly (SAA), a region over South America and the southern Atlantic Ocean where Earth’s magnetic field is significantly weaker. This reduced intensity allows high-energy solar particles to come closer to the planet than usual, increasing risks for satellites and space missions.
The SAA originates from processes deep within Earth’s core, where molten iron and nickel generate the planet’s magnetic field through the geodynamo effect. A combination of the magnetic axis tilt and the influence of a dense subterranean structure beneath Africa contributes to disruptions in field strength. This has led to the development of a localised area of reversed polarity, further weakening the region’s magnetic shielding.
Satellites passing through the SAA experience increased exposure to charged solar particles, leading to potential system malfunctions known as single event upsets (SEUs). These disruptions can cause data corruption or, in severe cases, permanent damage to critical components. To minimise risks, some spacecraft power down non-essential systems while crossing the anomaly. The International Space Station (ISS) also passes through the SAA regularly, affecting onboard instruments.
Satellite data from NASA and ESA confirm that the SAA is shifting northwest while expanding. Researchers have observed that it is splitting into two distinct regions of minimum magnetic intensity, creating additional high-risk zones for satellites. These changes complicate the modelling of geomagnetic conditions and require continuous monitoring to update space mission protocols.
Earth’s magnetic field typically deflects solar wind particles, preventing them from reaching the surface. However, in the SAA, weakened shielding allows more particles to enter, particularly during solar events like coronal mass ejections (CMEs). Studies show that the radiation levels in this region are significantly higher, making it a focus for heliophysics research.
NASA combines satellite data with geophysical simulations to track the evolution of the anomaly. The information contributes to global models such as the International Geomagnetic Reference Field (IGRF), which helps scientists predict future magnetic field changes. This approach, similar to weather forecasting but on longer timescales, is essential for planning future space missions and understanding Earth’s core dynamics.
While the current expansion of the SAA is notable, geological records indicate that similar anomalies have occurred before. Studies suggest that comparable weak spots in Earth’s magnetic field may have existed as far back as 11 million years ago. Researchers emphasise that this phenomenon does not signal an imminent magnetic pole reversal but is part of Earth’s long-term geomagnetic variations.