South Atlantic anomaly: A dent redefines satellite safety
NASA is monitoring the South Atlantic Anomaly (SAA), an unusual phenomenon in Earth's magnetic field. This region, characterised by a weakened magnetic field, has drawn scientists' interest and concern. According to Science Alert, this anomaly is particularly significant for satellites and spacecraft exposed to solar radiation in the affected area.
The SAA, described by NASA as a "dent" in Earth's magnetic field, does not directly impact life on Earth. However, satellites orbiting at low altitudes, including the International Space Station (ISS), regularly pass through this region, which can lead to failures in electronic systems. Interactions with high-energy protons from solar radiation can damage these systems and may even cause permanent failures.
Anomaly in Earth's magnetic field
According to Science Alert, satellite operators often shut down sensitive systems during passages through the anomaly to minimise the risk of data loss or serious damage. NASA is actively monitoring the phenomenon to develop methods to mitigate risks and better understand its nature.
In 2020, Terry Sabaka from the Goddard Space Flight Centre noted that the anomaly is caused by a complex interaction of magnetic fields generated by various sources. The primary source is the movement of liquid iron in Earth's outer core, which generates electric currents responsible for creating the magnetic field.
Additionally, a large mass of dense rocks, known as the "large low shear velocity province" (LLSVP), located about 2,900 kilometres under the surface of Africa, may disrupt this process. NASA suggests that the weakening of the magnetic field in this region is likely the result of local fields with reversed polarity.
NASA research indicates that the SAA is not static. In 2016, a team led by Ashley Greeley discovered that the anomaly was slowly drifting westward. Furthermore, research from 2020 showed that the anomaly is beginning to split into two parts, creating two separate centres of minimum magnetic field intensity. Additionally, analyses suggest that the SAA is not a new phenomenon.
Science Alert points out that a study published in July 2020 indicates that similar anomalies may have occurred on Earth as far back as 11 million years ago. This discovery challenges the theory that the current anomaly is a precursor to a global magnetic pole reversal, which occurs every few hundred thousand years. Scientists still have many questions about the SAA and the phenomenon's future. They believe it could provide valuable insights into the evolution of Earth's magnetic field and its impact on technology and life on Earth.
