South Atlantic Anomaly

This leads to an increased flux of energetic particles in this region and exposes orbiting satellites (including the ISS) to higher-than-usual levels of ionizing radiation.

Since its initial discovery in 1958, the southern limits of the SAA have remained roughly constant while a long-term expansion has been measured to the northwest, the north, the northeast, and the east.

As the geomagnetic field continues to weaken, the inner Van Allen belt gets closer to the Earth, with a commensurate enlargement of the SAA at given altitudes.

[8] During the Middle Holocene, the Earth's magnetic field in the region occupied by the SAA was relatively calm and quiescent, contrasting with its present day activity.

[9] The South Atlantic Anomaly seems to be caused by a huge reservoir of very dense rock inside the Earth called the African large low-shear velocity province.

This suggests the Van Allen belt confines antiparticles produced by the interaction of the Earth's upper atmosphere with cosmic rays.

The anomaly transiently disabled a direction-finding mechanism, causing the satellite to rely solely on gyroscopes that were not working properly, after which it spun out of control, losing its solar panels in the process.