The South Atlantic Anomaly (AAS), refers to a region in the southern Atlantic Ocean where the Van Allen radiation belts , (whose mission is to be traps of dangerous particles loaded with protons and electrons from the solar wind and cosmic rays preventing them from hitting the earth and destroying life on our planet).
They are less than 500 kilometers from Earth, these belts are normally located between 1,000 and 5,000 kilometers, due to a depression in the intensity of the Earth’s magnetic field, it is estimated that in this area it has values lower than the half the planet’s average, which implies an area more vulnerable to harmful cosmic radiation. This is believed to be due to the fact that the center of Earth’s magnetic field is skewed from its geographic center. Others believe it is due to a side effect of a geomagnetic reversal associated with processes inside the planet.
The “South Atlantic anomaly” is of great importance to satellites and other spacecraft that orbit hundreds of kilometers of altitude with orbital inclinations of 35 ° and 60 °, since these orbits carry these satellites through the anomaly of Periodically, exposing them for several minutes to strong radiation affecting the operation of instruments in orbit and potentially dangerous to the health of astronauts, is also of importance for air navigation.
AAS dimensions: approx 560 km.
The international space station , which orbits at a tilt of 51.6 °, required extra armor to deal with this problem, and the extremely expensive Hubble Space Telescope makes no observations when passing through this region by turning off its instruments.
The position of this anomaly is not fixed, but drifts slowly due to the differential rotation between the Earth’s core and its surface, moving between 0.3 and 0.5 degrees per year. Currently located above Brazil, Argentina and the South Atlantic, the danger zone is slowly moving towards the South Indian Ocean. This means that in a period of between 700 and 1000 years the anomaly should complete a complete turn around our planet. But since it has only been detected a few decades ago, scientists are not completely sure how this phenomenon evolves.
In fact, the intensity of the Earth’s magnetic field in general is weakening at high speed. Measurements made with a time difference of 20 years between one and the other show that if the field were to continue at this rate it could disappear completely in about 1000 years, which suggests that we are in the preliminary stages of a change of direction at the magnetic poles, something that has happened several times in Earth’s history. If this is true, what we see today as an anomaly would be normal for the entire surface of the Earth, since without a magnetic field there would be no belt of particles to protect us.