Swarm is a constellation of three satellites that study Earth’s geomagnetic field. This magnetic field that extends from Earth’s interior into space is thought to be produced largely by an ocean of liquid iron in the planet’s outer core. Other sources of magnetism include magnetised rocks in the crust.
And although we might not normally think of oceans as generating magnetism, the salty sea water is a moderate electrical conductor. This means that as tides flow across Earth’s magnetic field, they generate weak electric currents, which in turn induce small magnetic signals – that can be detected from space.
With its satellites flying at an altitude between 462 km and 511 km, Swarm measures Earth’s magnetic field more accurately than ever before. It can detect faint tidal signatures and distinguish them from other stronger magnetic field sources from Earth’s interior.
“This study shows that Swarm can provide data on properties of the entire water column of our oceans.” says Anja Strømme, ESA’s Swarm Mission Manager.
Swarm’s data can also provide insights into the distribution of magma, which could in future support better understanding of events such as the Hunga-Tonga volcanic eruption of 2022.
The study of these signatures made the front cover of the world’s oldest scientific journal, Philosophical Transactions of the Royal Society A, and was conducted by a team from the University of Cologne and the Technical University of Denmark.
See www.esa.int for more information.
