Delving Into Mysterious Irregularity Of Earth's Magnetic Field: Observatory Being Built In Middle Of Atlantic Ocean

The new geomagnetic observatory is located on the island of Tristan da Cunha and was inaugurated on Friday 14 November by the island’s roughly 300 inhabitants and a few of the researchers on the project.

Tristan da Cunha is the remotest inhabited island in the world and is also located right in the middle of the South Atlantic Anomaly, which is the area where the Earth’s magnetic field is weakest. This makes it incredibly interesting for the Danish researchers, who are working to understand the Earth’s magnetic field and the way in which it affects satellites, for example.

“Until now, Denmark has mostly been involved in projects that measure the magnetic field from space, with the Ørsted satellite and the future Swarm satellite mission, as well as the measuring stations in Greenland,” says Professor Nils Olsen of DTU Space. “With the observatory on Tristan da Cunha, we will have a measuring station in the Tropics right in the middle of the South Atlantic Anomaly, where the strength of the magnetic field is only half as high as in Denmark.”

The Earth’s magnetic field is losing strength

At present the strength of the Earth’s magnetic field is decreasing by 5% every hundred years and researchers do not know why or what the consequences will be. In the South Atlantic Anomaly, the strength of the magnetic field is decreasing ten times as fast and the measuring station will therefore also give the researchers the opportunity to learn more about the consequences of the global weakening of the magnetic field.

The magnetic field protects the Earth from radiation from space and the area around the South Atlantic Anomaly is therefore very poorly protected. In the Anomaly, the radiation belts that surround the Earth, the van Allen belts, are very close to the surface of the Earth. This is, among other things, significant to satellites, which suffer by far the majority of faults when they fly through this area.

Six days’ sailing from Cape Town

“Opening the observatory is a milestone in our research,” says senior researcher Jürgen Matzka from DMI, who is heading the project. “Finding a suitable location for the cabin on the island was a major logistical challenge, and we had a lot of help from South African colleagues and the French firm of engineers EnviroConsult. The cabin is also built exclusively of wood and brass in order not to disturb the magnetic measurements.” Shipping instruments to the island is no mean feat, as Tristan da Cunha is six days’ sailing from Cape Town, and there is no port or airport on the island.