Satellite Trio to Study the Earth's Magnetic Field in Unprecedented Detail

The European Space Agency (ESA) launched three identical satellites Friday that together will help researchers measure the Earth's magnetic field.

"The magnetic field of the Earth is our shield against cosmic particle radiation," Johanna Wanka, fedearl minister of education and research, said in a statement. "But it is subject to natural fluctuations, from the Earth's interior or eruptions on the Sun. Improving the exploration of its function and recording space weather data more accurately allows us to draw conclusions for life on our planet."

The trio comprise the ESA's SWARM mission, part of the agency's "Living Planet" program, and are designed to fly in an "optimized formation," with two hovering at an altitude of 450 km and with a distance of 150 km between them, and the third at an altitude of 530 km. Doing so will allow the satellites to observe the individual components that influence the magnetic field.

The field is generated 2,900 km below the crust by the flow of electrically conducting liquid iron in the Earth's outer core, and is affected by the conductivity and dynamics of the overlying mantle, found up to 40 km below the planet's surface. The Sun, currents in near-Earth space and magnetized rocks of the Earth's crust all contribute to the magnetic field.

"From its distance of 150 kilometers, the lower flying SWARM pair can look at the magnetic field of the Earth's crust with a stereo view," said Hermann Lühr, one of the three principal investigators of the mission. "We can therefore analyze this component with very high accuracy."

The third satellite will, over time, fly in progressively increasing angles to the path of the lower pair, gathering measurements with unprecedented precision.

An added bonus is the possibility of observing space weather with similarly unheard of accuracy. This includes magnetic storms generated by our Sun and even distant stars, and that possess the power to debilitate satellite communication and electrical power over an entire region.