NASA Tracks Huge and Growing Anomaly in Earth’s Magnetic Field: ScienceAlert

NASA is actively monitoring a strange anomaly in Earth’s magnetic field: a giant region of low magnetic density in the sky above the planet, stretching between South America and southwest Africa.

This broad and growing phenomenon, called the South Atlantic Anomaly, has intrigued scientists for years, perhaps none more so than NASA researchers.

The space agency’s satellites and spacecraft are particularly vulnerable to the weak magnetic field strength within the anomaly, and the resulting exposure to charged particles from the sun.

The South Atlantic Anomaly (SAA) — likened by NASA to a “bending” in Earth’s magnetic field, or a kind of “crack in space” — generally does not affect life on Earth, but the same cannot be said of orbiting spacecraft (including That’s the International Space Station), which passes right through the anomaly as it orbits the planet at low altitudes in Earth’s orbit.

During these encounters, the reduced magnetic field strength within the anomaly means that technological systems aboard the satellites can short-circuit and malfunction if they collide with high-energy protons emitted from the sun.

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These indiscriminate strikes would typically result in low-level malfunctions, but carry the risk of causing significant data loss, or even permanent damage to key components—threats that oblige satellite operators to routinely shut down spacecraft systems before spacecraft enter the drift zone.

Mitigating these risks in space is one reason NASA pursues the SAA. Another is that the mystery of anomalies presents a great opportunity to investigate a complex and difficult-to-understand phenomenon, and NASA’s vast resources and research groups are uniquely designated to study their occurrence.

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

The primary source is a swirling ocean of molten iron within the Earth’s outer core, thousands of kilometers underground. The movement of that mass generates electric currents that create the Earth’s magnetic field, though not necessarily uniformly, it seems.

A huge reservoir of dense rock called the African Great Low Shear Province, which lies about 2,900 kilometers (1,800 miles) below the African continent, disturbs field generation, resulting in a significant weakening effect – which is aided by the planet’s magnetic tilt on its axis.

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

“More specifically, a localized field of opposite polarity grows stronger in the SAA region, making the field strength very weak, weaker than that in the surrounding regions.”

Satellite data indicating SAA cleavage. (Department of Geomagnetism, DTU Area)

While many scientists still do not fully understand this anomaly and its implications, new insights are constantly shedding light on this strange phenomenon.

For example, one study Led by NASA heliophysicist Ashley Greeley in 2016, it revealed that the SAA is drifting slowly in a northwesterly direction.

However, he doesn’t just move. More importantly, the phenomenon appears to be in the process of splitting in two, as researchers discovered in 2020 that the SAA appeared to split into two different cells, each representing a separate center of magnetic minimum within the larger anomaly.

What this means for the future of the Syrian Arab Army remains unknown, but in any case there is evidence to suggest that the anomaly is not a new manifestation.

A study published in July 2020 indicated that this phenomenon is not a freak recent event, but rather a recurring magnetic event that may have affected Earth as early as 11 million years ago.

If so, that could indicate that the South Atlantic Anomaly is neither a cause nor a harbinger of an inversion of the entire planet’s magnetic field, which is something that does happen, if not for hundreds of thousands of years at a time.

Obviously, huge questions remain, but with so much of this massive magnetic weirdness out there, it’s good to know that the most powerful space agency in the world is watching it as closely as it is.

“Although SAA is slow moving, it does go through some change in morphology, so it is also important that we continue to monitor it through ongoing missions,” He said racing.

“Because that’s what helps us make models and predictions.”

A previous version of this article was published in August 2020.