Understanding Earth’s protective shield
The existence of Earth’s magnetic field is largely thanks to an ocean of swirling iron that makes up the outer core 3000 km under our feet. Driven by convection, it acts like the spinning conductor in a bicycle dynamo generating electric currents and the changing electromagnetic field.
Other sources of magnetism are the minerals in Earth’s mantle and crust, while the ionosphere and the magnetosphere also play a role. Since salt water is conductive, oceans make an additional, albeit weak, contribution to the magnetic field.
By untangling and modelling the many sources and strengths of the continuously changing magnetic field, Swarm is set to advance many areas of Earth science.
One of the few ways of probing Earth’s liquid core is to measure the magnetic field it creates and how it changes over time. Since variations in the field directly reflect the flow of fluid in the outermost core, new information from Swarm will further our understanding of the physics and dynamics of Earth’s stormy heart.
The constellation will produce, for the first time, global 3D images of electrical conductivity in the mantle to help understand its chemical composition and temperature. By mapping the magnetic fingerprints in Earth’s crust, this unique mission will result in an improved understanding of plate tectonics.
In addition, Swarm will also provide a better understanding of space weather and the way charged particles carried in solar winds enter the Earth system. This is important for protecting satellite technologies, radio communications, navigation and power infrastructures.
Uniquely, a better knowledge of electric currents in the atmosphere will also allow us to learn more about the composition of the Earth’s mantle.
With evidence pointing to a weakening magnetic field, it is more important than ever to understand how it is generated and the processes causing it to fluctuate. This is necessary for adopting precautionary measures and for developing new technologies to cope with solar storms.