Swarm

ESA’s Swarm mission will unravel one of the most mysterious aspects of our planet: the magnetic field.

Although invisible, the magnetic field and electric currents in and around Earth generate complex forces that have immeasurable impact on everyday life. The field can be thought of as a huge bubble, protecting us from cosmic radiation and charged particles that bombard Earth in ‘solar winds’. Without this protective shield, the atmosphere as we know it would not exist, rendering life on Earth virtually impossible.

Even as it is, strong solar storms have the potential to cause power and communication blackouts, and also to damage satellites orbiting Earth. A visible display of what happens when charged particles collide with atoms and molecules in the upper atmosphere can be seen as waves of luminous green light in the polar skies – the aurora borealis and aurora australis.

Earth’s magnetic field is in a permanent state of flux. Magnetic north wanders, and every few hundred thousand years the polarity flips so that a compass would point south instead of north. Moreover, the strength of the magnetic field constantly changes – and it is currently showing signs of significant weakening.

Swarm is ESA’s first constellation of satellites to advance our understanding of how Earth works. Harnessing European and Canadian technological excellence, the three Swarm satellites will measure precisely the magnetic signals that stem from Earth’s core, mantle, crust and oceans, as well as its ionosphere and magnetosphere.

By analysing the different characteristics of the observed field, this state-of-the-art mission will lead to new insight into many natural processes, from those occurring deep inside the planet to weather in space caused by solar activity. In turn, this information will yield a better understanding of why the magnetic field is weakening.

The geomagnetic field models resulting from the mission will provide new insights into Earth’s interior. These data along with measurements of atmospheric conditions around the orbiting satellites will further studies into Earth’s weakening magnetic shield, space weather and radiation hazards.

As well as furthering science, the measurements delivered by the three Swarm satellites will be valuable for a range of applications. For example, the data will be put to practical use to help improve the accuracy of navigation systems including those systems carried on satellites, to advance earthquake prediction and to improve the efficiency of drilling for natural resources.