Swarm starts mission to monitor Earth’s magnetic field

The three-satellite Swarm constellation, launched into a near-polar orbit by a Russian Rockot launcher, is expected to provide new insights into the workings of the magnetic shield that protects Earth’s biosphere from charged particles and cosmic radiation.

Over the next four years they will perform precise measurements to evaluate its current weakening and understand how it contributes to global change.

The Rockot launcher lifted off from the Plesetsk spaceport in northern Russia at 12:02 GMT today. Around 91 minutes later, its Breeze-KM upper stage released the three satellites into a near-polar circular orbit at an altitude of 490km. Contact was established with the trio minutes later through the Kiruna station in Sweden and the Svalbard station in Norway.

All three satellites are controlled by ESA teams at the European Space Operation Centre in Darmstadt, Germany. They will soon deploy their 4m-long instrument booms and over the next three months of commissioning, their scientific payloads will be verified and they will move to their respective operational orbits.

The lower pair will fly in formation side by side, about 150 km (10 seconds) apart at the equator and at an initial altitude of 460km, while the upper satellite will rise to a higher orbit of at 530km.

In a statement, Volker Liebig, ESA’s director for Earth observation said: ‘Swarm is about to fill a gap in our view of the Earth system and in our monitoring of global change issues. It will help us to better understand the field that protects us from the particles and radiation coming from the Sun.’

Swarm is ESA’s fourth Earth Explorer mission and follows CryoSat, GOCE and SMOS satellites, all of which are designed to increase knowledge of Earth and its environment.

The combination of data collected by Swarm will provide information on the sources of the magnetic field inside Earth. This includes understanding how the magnetic field is related to the motion of molten iron in the outer core, how the conductivity of the mantle is related to its composition, and how the crust has been magnetised over geological timescales.

They will also investigate how the magnetic field relates to Earth’s environment through the radiation belts and their near-Earth effects, including the solar wind energy input into the upper atmosphere.

Swarm will also be able to distinguish between the various sources of Earth’s magnetic field and ensure continuity in its monitoring from space in conjunction with measurements from ground observatories.

Earth’s magnetic field plays a major role in protecting the biosphere because it generates a bubble around Earth that deflects charged particles and traps them in the radiation belts. This shielding protects all life on Earth from the bombardment of heavy ions coming from the Sun and deep space.

Since the 1980s, previous missions have showed this field to be weakening, which could be a sign that the north and south magnetic poles are beginning to reverse.

Although such inversions usually take thousands years to complete, a further weakening of Earth’s magnetic protection could lead to an increase in events that damage orbiting satellites or disrupt power grids and other electrical systems on the ground.