It has been nicknamed the Bermuda Triangle of space. Spacecraft passing through are prone to electronic malfunctions, which have caused at least one spacecraft to break up in flight. Astronauts’ laptop computers are disabled, and astronauts themselves report seeing flashing lights that no instruments can detect.
This region of near-Earth space is called the South Atlantic Anomaly. As cosmic distances go, it is a pretty close neighbor to the Bermuda Triangle, located in a region above the Atlantic Ocean between Africa and South America, dipping as close as 200 miles to Earth.
A Peculiar Corner of Space
While a popular legend has manifested about ships and planes traversing the Bermuda Triangle being affected by strange instrument readings, sometimes with deadly results, no investigation has ever confirmed any such effects.
In contrast, according to David Crookes at Space.com, the Anomaly is a well-known distortion of Earth’s magnetic field, charted by both Earth-based explorers and spacecraft. We even know what causes it, in a general way.
What we don’t know are crucial details that would help us understand how the Anomaly developed, why it is currently undergoing changes and what the consequence of those changes could be — not only for future space exploration but for the future of human life and civilization here on Earth.
When Magnetism Goes Awry
The short-form explanation of the South Atlantic Anomaly is that it is a distortion in Earth’s magnetic field. The basic principle of this magnetic field is similar to that of a bar magnet. But Earth’s magnetic field is produced by the very slow, but enormously powerful churning of Earth’s liquid iron core.
This process is not perfectly symmetrical. Earth’s magnetic poles do not line up exactly with the geographical North and South poles. The centerline of the magnetic field is also offset by about 400 miles from the actual center of the Earth.
But what happens deep inside Earth does not always stay deep inside Earth. Energetic, charged particles from the sun get trapped in Earth’s magnetic field, forming the Van Allen radiation belts. And because of the magnetic field’s offset, the Van Allen belts dip closest to Earth’s surface over the Atlantic ocean between Africa and South America. This low overhang of the Van Allen belts is the South Atlantic Anomaly.
The Anomaly and the Van Allen Belts
The Anomaly is a problem for space exploration because most satellites orbit just a few hundred miles above Earth, this being the easiest region of space for us to reach. For the most part, these satellites are safely below the Van Allen belts, which Space Center Houston describes as “two donuts of seething radiation.” But whenever a satellite’s orbit crosses the Anomaly, it passes through the low-hanging sections of the Van Allen belts, exposing it to a period of intense radiation.
This radiation is the cause of the electronic oddities and failures that have afflicted spacecraft passing through the Anomaly. One such malfunction, aboard Japan’s Hitomi spacecraft, triggered an uncontrolled rotation that eventually tore the craft apart. Radiation effects also produce the light flashes reported by astronauts.
Heavy radiation armor had to be included in the International Space Station design to protect its crew when it passes through the Anomaly. Future space exploration will only increase the number of spacecraft — and humans — passing through the Anomaly, which will require special protection.
But there are also implications for people here on Earth. The Anomaly is gradually weakening and changing shape, reports Stephanie Pappas at Space.com.
Meanwhile, ScienceAlert notes indications that it is quite possibly breaking into two separate anomalies. This may be related to the phenomenon of Earth’s magnetic field periodically reversing directions.
This matters, because the same Van Allen belts that are dangerous to spacecraft also help to protect Earth itself from dangerous radiation. If Earth’s magnetic field starts to fade and reverse, we do not yet know what the impact might be on human life and health, or on the host of earthbound electronic devices that we rely on.
All of this makes continued study of the South Atlantic Anomaly a very big deal.