ESA Swarm mission

Swarm constellation.

The European Space Agency (ESA) will launch a new satellite mission called Swarm on 22 November 2013.

The mission consists of three identical satellites which will measure the strength and direction of Earth’s magnetic field to new levels of precision.

These new data will be processed by BGS (amongst others) to produce the most accurate maps of the Earth’s magnetic field ever.

Magnetic field sources

The magnetic field we measure comes from four main sources:

  • the main field from the Earth’s core
  • the field from the Earth’s crust (magnetic rocks)
  • the upper atmosphere (ionosphere)
  • the interaction of the Earth and the Sun’s magnetic fields (magnetosphere)

In order to best measure the field, the satellites will orbit in a unique configuration. Two satellites will fly side-by-side at height of 450 km, while the third satellite will fly at an altitude of 530 km.

The lower two satellites will give very detailed measurements of the magnetic field generated by the rocks in the Earth’s crust, which are difficult to detect otherwise.

The upper satellite will give a simultaneous measurement at a different location. This is important for identifying magnetic fields generated by the magnetosphere and ionosphere.

Better maps and models

ESA have commissioned the BGS and five other European research institutes to produce specific types of magnetic field maps and processed data for the general public.

The combination of all three satellites will provide better maps and models of the main field which are primarily used for navigation purposes. For example, for shipping, in smartphone map applications, or directional drilling for oil and gas.

The measurements will also help us better understand the impact of space weather events on technology such as satellite communications and GPS accuracy.

Each satellite is about nine metres long, consisting of the main body covered in solar panels and a four-metre boom on which the sensitive magnetic field measuring instruments sit — away from electrical and magnetic interference.

The magnetic field is measured by two instruments — an instrument at the end of the boom which measures the strength of the field and another in the middle of the boom, which measures the direction of the field, using the star cameras to work out the orientation of the satellite.

The BGS Geomagnetism Team have spent the past three years preparing for the launch of Swarm. All data will be provided for free by ESA on their website.

Swarm satellite instrumentation

Swarm satellite instrumentation.


For more information contact Dr Ciaran Beggan or visit the BGS Geomagnetism website