Astronauts and satellites have been reporting odd glitches and increased radiation in this area for years. Space agencies must now reconsider how they fly and safeguard hardware in orbit because accurate magnetic data reveals that Earth’s protective field is changing more quickly than anticipated.
What is happening to the magnetic shield of Earth?
The Earth’s magnetic field surrounds the planet like a massive uneven protective bubble. It deflects a lot of charged particles that the Sun throws out and lessens the impact of cosmic rays.
More radiation may seep closer to Earth when that shield becomes weaker in a particular location. This is precisely what is taking place, high above the South Atlantic and parts of southern Africa regions.
The Ordinary serum called filler in a bottle gives skin smoother youthful appearance in your 40s
The Earth’s magnetic field is considerably weaker in the South Atlantic Anomaly, a large area that is still expanding.
Scientists now estimate that this anomaly covers about 1% of Earth’s surface, or half of Europe, based on more than ten years of satellite measurements. The weakest point is slightly over 22,000 nanoteslas which is much less than the 40,000–60,000 nanoteslas that are usually measured elsewhere.
It’s not a slow decline. The local field there has decreased by hundreds of nanoteslas since the mid-2010s, and the rate has accelerated recently. The anomaly’s eastern portion, southwest of Africa, is disappearing more quickly than the part over South America, suggesting intricate processes occurring deep within the planet.
The cost is borne by satellites.
The South Atlantic has become a high-risk area for satellites operating at altitudes between 400 and 1,000 kilometres.
More high-energy particles from the inner Van Allen radiation belt can dip closer to Earth in this area due to the weaker magnetic field. A denser radiation storm strikes spacecraft delicate electronics as they travel through.
How radiation affects spacecraft components
Engineers refer to these single event effects as the result of charged particles penetrating electronic chips and memory units. In actuality, that may imply:
- Onboard computer resets that happen on their own
- data corruption in memory modules
- temporary sensor malfunctions, infrequent image artefacts, and long-term component damage
In order to minimise damage, certain Earth-observation satellites frequently turn off their instruments while traversing the South Atlantic Anomaly. Others experienced inexplicable glitches that subsequently matched their path through the weakened magnetic field.
Not every craft carries the same level of risk. Satellites that are older or constructed using commercial off-the-shelf parts are typically more vulnerable. Hardened electronics are used in high-reliability missions like weather or military satellites, but they come at a cost in terms of mass power consumption, and development funding.
The health of astronauts is also at risk.
The International Space Station (ISS) travels through the anomaly multiple times every day while orbiting at a distance of about 400 kilometres altitude. Radiation monitors on board detect discernible spikes when it does.
The additional exposure accumulates over time, but short-term doses stay below emergency levels. The South Atlantic crossings are included in the lifetime radiation budget that space agencies currently monitor for each astronaut.
Even at doses far below acute illness thresholds, long-term exposure to ionising radiation has been linked in medical studies to increased risks of cancer cataracts and cellular damage.
To keep individual exposure as low as practically possible, future commercial stations in comparable orbits and any long-duration crew missions that frequently pass through this area will need to incorporate additional shielding and improved duty schedules.
What the anomaly tells us about the interior of Earth
Space weather is not the only factor contributing to the declining magnetic field in the South Atlantic. It is a sign of fluctuating molten iron flows in the Earth’s outer core, some 3,000 kilometres below the surface.
The geodynamo, a swirling convecting liquid metal that conducts electricity and produces a worldwide magnetic field, is what produces the magnetic field there. That field is neither static nor straightforward.
Reversed flux patches, where magnetic lines dip back into Earth rather than stream outward, are found in the core field beneath the South Atlantic.
The South Atlantic Anomaly is a magnetic dent that we detect at the surface as a result of these reversed patches cancelling out a portion of the surrounding field. One such patch is gradually moving westward beneath southern Africa, deepening the local minimum, according to data from Europe’s Swarm satellite trio.
Geophysicists believe that these patches are influenced by changes at the boundary between the solid mantle above and the liquid outer core. The magnetic map at the surface can be reshaped by slight variations in temperature and composition, which can change how the core fluid circulates.
Is a pole flip imminent?
Over millions of years, the magnetic poles of Earth have flipped numerous times. The north and south magnetic poles swap places during a complete reversal, and the field weakens and reorganises.
Some have questioned whether we are witnessing early indications of such a reversal due to the South Atlantic current weakening. On human timescales, that scenario is not supported by long-term models or the most recent satellite data.
Instead of being the first sign of an impending global pole reversal, the South Atlantic Anomaly appears to be a local variation in a restless field.
However, scientists anticipate that the field will continue to develop over decades to centuries, which is important for communications navigation and space operations.
A global magnetic field in motion
There are other regions that are changing besides the South Atlantic region. Swarm data reveal that Earth’s field is highly asymmetric with hot spots and weak zones shifting over time.
In the Northern Hemisphere, a strong magnetic region over Canada has been shrinking and fading since the mid-2010s period, while another over Siberia has been intensifying and expanding. This uneven behaviour helps explain why the magnetic north pole has been racing from Canada towards Russia faster than in previous centuries recorded.
| Region | Trend since mid-2010s | Effect |
|---|---|---|
| South Atlantic | Field strength decreasing, area expanding | Higher radiation for satellites and ISS |
| Canada | Field weakening, area shrinking | Magnetic north pole moving away |
| Siberia | Field strengthening, area growing | Magnetic north pole drifting towards Siberia |
This constant reshaping forces updates to the global magnetic models used in aviation charts, smartphone compasses and military systems. Airports at high latitudes, especially in Canada and Russia, have already had to rename runways as their magnetic headings shift.
How space agencies are adapting
Space engineers do not have the luxury of ignoring these trends. For each new mission, teams now weigh the added risks when orbits cross the South Atlantic Anomaly and other weak patches.
Typical mitigation steps include:
- using radiation-hardened chips or adding error-correcting circuits
- scheduling reboots or safe modes during anomaly crossings adding shielding around critical avionics and memory units
- adjusting orbit altitude to reduce time spent in the most intense zones
None of these fixes are free. Hardened components can lag behind commercial chips in performance. Extra shielding means more mass to launch. Orbit changes cost fuel and shorten mission lifetimes.
That trade-off becomes more acute as the anomaly spreads and deepens, capturing a larger slice of low-Earth orbit traffic, from climate satellites to broadband constellations networks.
