NASA is actively monitoring for a strange anomaly in Earth’s magnetic field: a giant region of lower magnetic density in the sky above the planet that stretches between South America and southwest Africa. This massive, evolving phenomenon, called the South Atlantic Anomaly, has intrigued and worried scientists for years, and perhaps none more so than NASA researchers. The space agency’s satellites and spacecraft are particularly vulnerable to the weakened magnetic field strength within the anomaly and the consequent impact of charged particles from the Sun.

The South Atlantic Anomaly (SAA), which NASA compares to a “pit” in Earth’s magnetic field or a type of “pit in space”, does not generally affect life on Earth, but the same cannot be said for orbiting spacecraft (including). The International Space Station) passes directly through the anomaly orbiting the planet in low Earth orbit. During these collisions, the reduced magnetic field strength within the anomaly means that technological systems on the satellites could shut down and malfunction if high-energy protons from the Sun were struck.

These random hits can often only cause low-level outages, but they run the risk of causing significant data loss and even permanent damage to key components—threats that force satellite operators to routinely shut down spacecraft systems before the spacecraft enters a region of anomaly.

Reducing these dangers in space is one of the reasons NASA monitors the SAA; the other is that the mystery of the anomaly provides an excellent opportunity to investigate a complex and elusive phenomenon, and NASA’s extensive resources and research teams are uniquely positioned to study it.

“The magnetic field is essentially a superposition of fields from many available sources,” geophysicist Terry Sabaka of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, said in 2020.

The main source is thought to be an ocean of molten iron swirling within the Earth’s outer core, thousands of kilometers below the ground. The movement of this mass creates electric currents that create the Earth’s magnetic field, but it seems that this is not necessarily uniform.

About 2,900 kilometers (1,800 mi) below the African continent, a massive reservoir of dense rock called the African Great Low Slip Zone is disrupting field formation, causing a sharp weakening of the effect facilitated by the planet’s magnetic tilt. area. axis.

“The observed SAA can also be interpreted as a result of weakening dipole field dominance in the region,” NASA geophysicist and mathematician Goddard Weijia Kuang said in 2020. Said.

“More specifically, the localized reverse polarity field increases strongly in the SAA region, thus making the field strength very weak, weaker than in the surrounding regions.”

While scientists still don’t fully understand this anomaly and its consequences, new ideas are constantly shedding light on this strange phenomenon.

For example, a 2016 study led by NASA heliophysicist Ashley Greeley found that the SAA is slowly drifting in a northwesterly direction. But this is not just a movement. Even more strikingly, the phenomenon appears to be in the process of splitting in two, and in 2020 the researchers discovered that the SAA appears to split into two separate cells, each representing a separate center of minimum magnetic intensity within the larger anomaly. What this means for the future of SAA is unknown, but in any case there is evidence that this anomaly is not new.

A study published in July 2020 showed that this phenomenon was not a recent freak event, but a recurrent magnetic event that may have affected Earth as early as 11 million years ago. If so, this could mean that the South Atlantic Anomaly is not the trigger or precursor of a magnetic field reversal that is actually occurring planet-wide, if not for hundreds of thousands of years at a time. Obviously, there are still huge questions, but with so much going on with this massive magnetic wonder, it’s good to know that the world’s most powerful space agency is watching it as closely as they do.

“Although the SAA moves slowly, it undergoes some changes in morphology, so it’s also important that we continue to observe it as we go about our missions,” Sabaka said. Said.