South Atlantic Anomaly 2015 through 2025 2160_p60

The bulk of Earth’s magnetic field originates deep within its core, at the boundary between the molten outer core and the solid mantle. The magnetic field extends past the surface into space and 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 (SAA), allows these particles to dip much closer to the surface. Particle radiation in the SAA can knock out onboard computers and interfere with the data collection of satellites that pass through it.

The SAA creates no visible impacts on daily life on the surface, and its weakening magnetic intensity is still within the bounds of what scientists consider normal variation. However, recent observations and forecasts show that the region is expanding westward and continuing to weaken in intensity. Observational data from 2015-2020 found that the SAA has recently started to split from a single valley, or region of minimum field strength, into two cells; and models out to the year 2025 show the split continuing in the future, creating additional challenges for satellite missions.

NASA’s geomagnetic and geophysical research groups are using observations and models to monitor and predict future changes in the SAA and the rest of Earth’s geomagnetic field – helping prepare for future challenges to satellites and humans in space.