When in 2012 the very first Dragon ship built by SpaceX first arrived and docked to the ISS, then in the report on this mission, among other things, there was a curious fact.
During the passage of the station over the Atlantic and South America on the “Dragon” there was some temporary failure in the remote control system, that is, the onboard equipment is out of order. Later it was restarted, and everything was fine again.
And this did not surprise the world astronautics at all. On huge screens in the Mission Control Centers in both Korolev and Houston, this region above the Earth is always highlighted.
Astronauts on board notice that it is there that “flashes” in their eyes flicker more often. And these “flashes” are nothing but charged particles from space that constantly pass through a person at a height of 400 kilometers. In other words, radiation.
Back in the late 90s, an instrument aboard the space shuttle Columbia measured the level of radiation in space at an altitude of about 300 kilometers.
It turned out that over the south Atlantic and Brazil it almost doubled – 413 microsieverts against 264. There is evidence that in this area of the ocean and in a considerable part of South America, even at sea level, the magnetic field is as weak as in any other place on an altitude of several hundred, or even a whole thousand kilometers.
That is, as in the ionosphere, in the highest and rarefied layers of our atmosphere. So satellite operators have long been accustomed to partially turning off their devices while they travel around these parts.
And all these are symptoms of the same amazing phenomenon called “South Atlantic Magnetic Anomaly”. Sometimes it is divided into Brazilian and Cape Town, but so far this area is a single whole. Although, according to the latest data, it is now expanding, slowly moving to the northwest and at the same time gradually splitting in two.
This is some mysterious failure, a hole in the Earth’s magnetosphere. As you know, it is the planet’s magnetic field that holds back and does not let solar and galactic deadly radiation reach us. In total, this “weak spot” in the magnetic shield extends over almost eight million square kilometers.
Scientists believe that this particular anomaly appeared around the beginning of the 19th century. The analysis of ancient rocks shows that such a situation with the Earth’s magnetic field is cyclical, that is, these fluctuations have been occurring periodically for at least many millions of years.
There are even predictions on this basis about how much longer we will observe radiation over the south Atlantic: about a few hundred years.
The causes of the anomaly are the subject of numerous studies and scientific disputes. One of the main versions is the uneven distribution of matter in the bowels of the Earth.
Geologists have determined that there are some vast areas of somewhat denser rock in the lower part of the mantle. And just one of these areas is located approximately under the African continent at a depth of about 2900 kilometers, it was called the Greater African Province.
So, scientists suspect that this impressive dense accumulation in the mantle goes a little deeper into the outer core of the Earth. Recall that the outer core is its “upper”, surrounding, liquid layer.
Molten iron is constantly mixed in it, a powerful electric current flows, hence the magnetic field of the planet. Accordingly, immersion in it of some harder piece interferes with this process.
So we get a noticeably weaker magnetic field approximately over this part of the world. And due to the fact that the Earth rotates along with all its contents, we observe the consequences not only over Africa, but also over South America.
It is worth mentioning that, in general, in recent centuries, the Earth’s magnetic field has been weakening, and this leads to considerations about a possible revolution of the magnetic poles.
Researchers are speculating whether the South American anomaly can be somehow connected with this, whether it is a harbinger of a magnetic flip.
By the way, when this happens, the names of the magnetic poles will finally coincide with the names of the geographic ones: now we have the South magnetic pole in the Arctic, and the North in Antarctica.