The magnetic field protects us, acting as a shield against the solar wind – stream of charged particles and radiation – that flows from the sun. The protection of this field also extends to include satellites orbiting near Earth.
But the South Atlantic Anomaly allows solar particles to get closer than before. Solar radiation could have a negative effect if satellites pass through this area, knock out their computers and collect data, according to NASA.
The South Atlantic Anomaly, new data have also shown, is weakening and expanding to the west. Moreover, it splits into two lobes, instead of one size one, which will cause further headaches for managing satellite missions.
Across a wide range of research areas, NASA scientists are examining the anomaly to prepare them for those challenges, as well as how it may affect humans in space.
Earth scientists at NASA are also checking the anomaly to see how these localized changes in the strength of the magnetic field can affect our atmosphere.
What damage can the anomaly cause?
If satellites traveling through this weak area in the magnetic field are hit by trigger particles, they can cause short circuit, glitch or even permanent damage. Thus, satellite operators regularly shut down satellite components as they travel through the anomaly so that they do not risk losing important instruments such as the entire satellite.
The International Space Station also runs through the anomaly. While the astronauts are safe inside the station, instruments on the outside of it can collect data and experience problems.
In fact, the anomaly is known to put powerboards back on the Global Ecosystem Dynamics Investigation mission, as GEDI, installed on the outside of the station, as often as once a month.
While this does not cause any material damage, it results in a few hours of lost data each month, according to Bryan Blair, the deputy chief investigator and instrument scientist of the mission, and a scientist lidar instrument at Goddard.
What causes it?
The Earth’s magnetic field is produced by its molten, iron-rich core, which lies in a constant state of motion 1,800 miles below the surface. These motions act as a generator, known as the geodynamo, and the electric currents that create the motions produce the magnetic field, according to NASA.
The north and south poles of the Earth also have magnetic field lines that extend, but they are not perfectly tuned as stable.
The motions of the outer core of the planet are variable, causing fluctuations in the magnetic field, and the magnetic pulse tilts and migrates. Together, these factors have helped create the South Atlantic Anomaly.
“The magnetic field is actually a superposition of fields from many current sources,” said Terry Sabaka, a geophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, in a statement.
A weak area in the magnetic field is more sensitive to close encounters with the solar wind, such as ejections of coronal mass, which are massive clouds of heated plasma and radiation emitted by the sun.
The Van Allen radiation belts, which surround the earth, are full of charged particles and plasma. These belts, shaped like donuts, can usually capture and hold the particles and radiation in place, so that they essentially jump from the earth’s magnetic field.
The belts form part of the Earth’s magnetosphere, as the area of space where the Earth’s magnetic field interacts with solar wind.
Closer to the two belts lies 400 miles from the Earth’s surface – a good distance to protect Earth and its satellites from radiation. It is more stable than the outer belt, which fluctuates and lies 8,400 to 36,000 miles above the earth’s surface.
But there’s a flip side to the Van Allen belts: More intense space water generated by the sun, which are rare events, can actually tighten the belts, deform the magnetic field and allow radiation and charged particles into our atmosphere.
Scientists are also studying particle radiation in the area where the anomaly lies with data collected by NASA’s Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) mission.
The mission operated between 1992 and 2012, and its data helped reveal that the anomaly was moving in a northwesterly direction, meaning that its location shifted as the geomagnetic field evolved.
“These particles are indeed connected to the magnetic field, which leads their motions,” said Shri Kanekal, a researcher in the Heliospheric Physics Laboratory at NASA Goddard, in a statement. “Therefore, any knowledge of particles also gives you information about the geomagnetic field.”
Preparing for the future
SAMPEX data has been used to design satellites that are less susceptible to failure if they encounter a problem going through the anomaly. The European Space Agency’s Swarm mission, launched in 2013, observes the Earth’s magnetic field.
Then scientists on Earth can create models and understand their current state. NASA scientists such as Sabaka and Weijia Kuang, who is a geophysicist and mathematician at NASA Goddard’s Geodesy and Geophysics Laboratory, combine data from various sources to predict how rapid changes may occur in the magnetic field ahead.
These NASA team members have contributed to the International Geomagnetic Reference Field. This collaborative effort helps with research on topics as varied as the Earth’s core and the outer limits of the atmosphere, and models the Earth’s magnetic field and its changes.
“This is similar to how weather forecasts are produced, but we work with much longer time scales,” Andrew Tangborn, a mathematician at Goddard’s Planetarium Geodynamics Laboratory, said in a statement.
Scientists at NASA will continue to observe the South Atlantic Anomaly with future missions so that they can make models and predictions as well as better understand the Earth’s core.
And missions like NASA’s Parker Solar Probe and the European Space Agency’s Solar Orbiter are helping us to stream the solar wind to Earth.
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