Swarm satellites shed light on near-Earth electric current systems

The three Swarm satellites have provided a first glimpse inside Earth and started to shed new light on the dynamics of the upper atmosphere.

The European Space Agency mission involves three satellites designed to identify and measure precisely these different magnetic signals from Earth. The planet’s magnetic field is thought to be largely generated by an ocean of superheated, swirling liquid iron that makes up the outer core 3,000 kilometres below the surface.

The latest data gives insights into behaviour of the magnetic field and electric current systems all the way from the ionosphere, about 100 kilometres above the surface, to the outer reaches of the protective magnetic shield.

Swarm’s mission will take four years while it measures and untangles the different magnetic signals that stem from Earth’s core, mantle, crust, oceans, ionosphere and magnetosphere.

The three satellites are identical, but to optimise sampling in space and time their orbits are different and change over the course of the mission’s life.

A series of scientific papers published recently in Geophysical Research Letters and collected in a special issue, looks at the first data. Rune Floberghagen, ESA’s Swarm Mission Manager, is elated.

“These results show that all the meticulous effort that went into making Swarm the best-ever spaceborne magnetometry mission is certainly paying off.”

One of the three lead proposers of the Swarm mission, Gauthier Hulot from IPG Paris, added, “Our magnetic field is largely generated by Earth’s outer core. The constellation provides detail on the way the field is changing and thereby weakening our protective shield.

“This is what will ultimately make it possible to predict the way this field will evolve over the next decades.”

The results are being presented at the 26th General Assembly of the International Union of Geodesy and Geophysics from 22 June to 2 July in Prague, Czech Republic.

An artist’s impression of the constellation of Swarm satellites at work.

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