Earth’s magnetic field is facing a notable issue. A weak spot over the South Atlantic Ocean, called the South Atlantic Anomaly (SAA), is expanding. This change has been tracked for over a decade by the European Space Agency’s Swarm satellites. Since 2014, this region has grown by an area that’s half the size of continental Europe.
Chris Finlay, a geomagnetism researcher at Danmarks Tekniske Universitet, highlights that understanding these changes is crucial. “It was expected, but confirming its continuous expansion is important,” he notes. His recent findings appear in the journal Physics of the Earth and Planetary Interiors.
Launched in 2014, the three Swarm satellites monitor Earth’s magnetic signals, helping scientists understand the geomagnetic field generated deep within our planet. This magnetic field protects us from harmful solar radiation. When charged particles from the Sun hit it, we often see stunning auroras in the sky.
However, as the weak spot grows, satellites and astronauts passing through could face increased radiation. Finlay warns that this could lead to more malfunctions in satellite systems and a heightened risk of health issues for astronauts, including DNA damage and a potential rise in cancer risk over time. Interestingly, while satellites may spend many years in orbit, astronauts usually spend only a few months at a time.
The geomagnetic field’s strength varies. Typically, it measures between 22,000 to 67,000 nanoteslas, while a fridge magnet is about 10 million nanoteslas! In the SAA, the field is currently at about 22,094 nanoteslas and continues to decline.
In contrast, regions with a strong magnetic field, like northern Canada and Siberia, are experiencing changes too. The field strength in Canada has dropped, while a stronger area in Siberia has expanded. Finlay admits that the reasons behind these changes are still a bit of a mystery but are related to the movements of liquid metal in Earth’s core.
Past records show that the magnetic field has weakened before without flipping. So while fluctuations are happening, a complete reversal isn’t anticipated anytime soon, according to Finlay.
To protect against the increasing risks from solar radiation, future spacecraft should be designed to withstand these changes better. Hagay Amit, a geophysicist from Nantes Université in France, emphasizes the need for continuous, high-quality geomagnetic measurements to gain insights into Earth’s dynamics.
As our understanding of the geomagnetic field grows, so does the need to consider its implications for technology and human health in space. The importance of monitoring these changes cannot be overstated.
This article originally appeared in EOS Magazine.
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