NASA is actively monitoring a strange anomaly in the Earth's magnetic field: we're talking about a huge region of low magnetic intensity in the sky above the planet that stretches between South America and southwest Africa.
This vast and emerging phenomenon, called the South Atlantic Anomaly, has intrigued scientists for years, and perhaps worries more than NASA researchers.
The space agency's satellites and spacecraft are particularly vulnerable to exposure to the weakened magnetic field strength within the anomaly and consequent charged particles from the Sun.
Life on Earth is generally unaffected by the South Atlantic Anomaly (SAA), which NASA likens to a "pit" or a kind of "space trough" in Earth's magnetic field. However, the situation is different for orbital spacecraft, such as the International Space Station, which pass directly through the anomaly as it orbits the planet at low Earth orbit altitudes.
Due to the weak magnetic field within the anomaly during these encounters, the technical equipment on the satellites is prone to short circuit and malfunction if affected by high energy protons from the Sun.
While these individual collisions typically cause only minor disruptions, they still have the potential to permanently destroy critical components or lose a lot of data, forcing satellite operators to regularly shut down spacecraft systems before approaching the anomalous zone.
One reason NASA monitors SAA is to reduce these risks in space; second, the mystery surrounding the anomaly presents a great opportunity to investigate a complex and challenging phenomenon, and NASA's extensive resources and research groups are particularly suited to studying it.
"The magnetic field is actually 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 boiling thousands of kilometers below the surface in the Earth's outer core. Although not continuous, the movement of this mass seems to generate electric currents that generate the Earth's magnetic field.
The severe weakening effect is due to a massive deposit of thick rock known as the African Great Low Shear Velocity Zone, located about 2.900 kilometers (1.800 miles) below the African continent. The tilt of the planet's magnetic axis also plays a role in this process.
Weijia Kuang, a geophysicist and mathematician at NASA Goddard, stated in 2020 that "the observed SAA can also be interpreted as a result of the weakening dominance of the dipole field in the region."
“More specifically, a localized field with reverse polarity grows strongly in the SAA region, resulting in a very weak field intensity, weaker than neighboring regions.”
While there is still much that scientists still don't fully understand about the anomaly and its effects, new information is continually illuminating this strange phenomenon.
For example, a 2016 study under the guidance of NASA heliophysicist Ashley Greeley revealed that the LAA is increasingly moving in a northwesterly direction.
But it doesn't just move. This phenomenon seems to be splitting in two, which is even more surprising. In 2020, the researchers found that the SAA appears to split into two separate cells, each representing a separate center of minimum magnetic intensity within the larger anomaly.
Exactly what this means for the future of SAA is unclear, but there is evidence to support the idea that the anomaly is not a new development.
According to a study published in July 2020, this phenomenon is not a one-time freak event, but a periodic magnetic event that may have affected Earth as much as 11 million years ago.
If this is the case, the South Atlantic Anomaly may mean that the planet's magnetic field as a whole is not the cause or precursor to the reversal; this happens at a time, albeit for periods of thousands or even millions of years.
While there are still many unanswered concerns regarding this enormous magnetic anomaly, it's comforting to know that the world's most powerful space agency is keeping a close eye on it.
According to Sabaka, although the SAA moves slowly, it undergoes some morphological changes, so it's crucial that we continue to monitor it through missions.
“Because that's how we make models and predictions,” the speaker said.
Source: sciencealert – SPACE 23 March 2023 ByPETER DOCKRILL
Günceleme: 24/03/2023 14:17