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Protecting nature

ESA’s Swarm prepares for flight

Swarm constellation
Swarm constellation

13 January 2012
There is an invisible magnetic field all around us. Although we don’t normally notice it, the Earth’s magnetic field is very important as it protects us from dangerous solar storms and space radiation. Without it, there would be no life on our planet. In order to measure this magnetic force with greater accuracy than ever before, ESA is preparing to send a special mission into orbit called Swarm.

The Swarm concept consists of a constellation of three satellites in three different polar orbits at heights of between 400 and 550 km. High-precision and high-resolution measurements of the strength and direction of the magnetic field will be provided by each satellite. Many of the sensitive instruments will be mounted on a 4 metre long boom to limit interference from the electrical systems on the spacecraft.
Swarm constellation
Swarm constellation
The magnetic field is thought to be created by swirling liquid in Earth’s iron-rich outer core, but we still don’t fully understand how it is generated and how it changes over time. For example, the surface locations of the north and south magnetic poles are continually shifting. The strength of the field also changes. From time to time, the poles actually reverse, so that the present north pole becomes the south pole. At such times, a magnetic compass would point south instead of north! Scientists hope that the Swarm mission will be able to solve these and many other magnetic mysteries.

In order to ensure that the measurements are as accurate as possible, the satellites have all undergone lengthy tests. Some of these were carried out in a ‘magnetically clean’ environment – a room with a wooden floor, located deep in a German forest, far from any other buildings. Once their test programme is completed, the Swarm trio will be delivered to the Russian spaceport at Plesetsk, for launch by a Rockot vehicle later this year.

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