Weak spot growing in the earth’s magnetic field can damage satellites

Earth’s pack of geomagnetic weapons has a chink, and it’s growing.

This weak spot in the magnetic field of our planet lies above the southern Atlantic Ocean, between South America and southern Africa. Since 2014, the dent has grown in size and started to split, while also getting weaker.

For humans on the ground, this is not a cause for concern: The protective field still protects the planet from deadly solar radiation. But the South Atlantic Anomaly, as it is aptly called, affects space travel, the International Space Station and low-orbit satellites throughout the region. This is because the higher amounts of charged solar particles that are sucking through can cause errors in computers and circuits.

That’s why NASA scientists are following this weak spot, the agency announced Monday.

“Those particles can be destroyed by satellite instrumentation, so it’s good to follow the South Atlantic Anomaly, and especially the changing form, so we can take preventative action,” Terence Sabaka, a NASA geophysicist, told NBC News.

The weak spot grows and splits

Scientists use a set of three satellites, collectively nicknamed Swarm, to hold tabs on the Earth’s changing magnetic field.

Some studies suggest that the total area of ​​the SAA has doubled in the last 200 years, and that the SAA is expanding year over year.

In the last five years or so, the anomaly may have split in half, according to scientists at NASA and the European Space Agency (ESA): One area of ​​magnetic weakness has developed over the ocean southwest of Africa, while another east from the south sits America.

The SAA has also weakened by 8% since 1970. This reflects what is happening to the Earth’s magnetic field as a whole: the field has lost an average of 9% of its power over the last 200 years, according to the ESA.

The weak spot spells trouble for satellites and the space station

A weaker field introduces more charged particles from solar wind to make its way through Earth’s protective screen. Typically, the magnetic field repels these particles or traps them in areas called Van Allen belts, which hang the particles 400 miles above the planet’s surface.

But in a belly like the SAA, those charged particles can get closer to Earth – so much closer that low-orbit satellites and the space station, which hangs about 220 miles up, are forced to pass through a region full of them.

This can cause problems with electronic systems, interrupt data collection, and lead to expensive computer components in space, such as the Hubble Space Telescope becoming obsolete. Hubble goes through the anomaly every day in 10 of its 15 orbits around the Earth, spending almost 15% of its time in this “hostile region”, according to NASA.

The ISS has additional protection to protect astronauts on board from solar radiation, but the instruments in and around the space station are not as well protected. So if solar particles hit an important component of any of those instruments, then she could completely free them.

Nothing has gone wrong yet, but the SAA causes ISS instruments such as the Global Ecosystem Dynamics Investigation mission, which observes the planet’s declining tree cover from space, to lose a few hours of data every month.

The ESA also notes that satellites flying through the region are “more likely to have technical malfunctions”, such as short glitches that could disrupt communications.

Therefore, it is common for satellite operators to close non-essential components as the objects continue through the SAA to lose instruments such as the entire satellite, according to NASA’s Goddard Space Flight Center.

The abdomen changes as the earth’s moving liquid metal core shifts

To predict how this dent will change in the future, NASA scientists are looking deep into the Earth.

The magnetic field exists thanks to floating liquid iron in the outer core of the planet, about 1,800 miles below the surface. Anchored by the north and south magnetic poles (which shift the trend and even reverse every million years or so), the field grows and blows in strength, undulating based on what is happening at the core.

Periodic and sometimes random changes in the distribution of that turbulent liquid metal can cause idiosyncrasies in the magnetic field such as the SAA. If you imagine the field as a series of rubber bands that push through the magnetic pulse, then in the core essentially different bands change in different places.

These geomagnetic drag buses affect how strong or weak certain parts of the field are, and can also cause the magnetic north pole to shift its location.

That NASA is working continuously to predict these tugs and the effect they will have on the SAA, through a model that predicts the future of the Earth’s magnetic field.

“This is similar to how weather forecasts are produced, but we are working with much longer time scales,” NASA mathematician Andrew Tangborn said in the release.