Space Tuesdays: Measuring Earth’s Magnetic Armor with Swarm

The next #CNEStweetup will explore the mission to understand the planet’s magnetic field, where it comes from and where it’s going

In 1859, telegraph operators across Europe and North America were astonished to receive shocks from their instruments, while their telegraph paper caught fire. Even when they disconnected their batteries, messages could still be sent along the live wires. The sun had released a blast of charged particles in the direction of the Earth, whose interaction with the planet’s magnetic field produced a huge geomagnetic storm that fried telegraph cables in its wake. A solar storm of the same size occurred in 2012. This time, thankfully, it missed the earth, but what will happen when it hits us full on? The vast, long-lasting power outages that could result would, for a time, change life as we know it. Understanding Earth’s magnetic field suddenly seems paramount.

The next Space Tuesday (Mardi de l’espace) will explore Swarm, the space mission aiming to do just that. Come discuss the study of this fascinating boundary between Earth and Space, with two experts: Mioara Mandea, Solid Earth Programme Manager for the CNES, and Gauthier Hulot, an expert on geomagnetism at the IPGP. Join us Tuesday 20 January 2015, from 7:30pm at the Café du Pont Neuf in Paris, or on Twitter via the hashtag #CNESTweetup. 

 Image: ESA/ATG MedialabESA’s constellation of three Swarm satellites is designed to identify and measure the different magnetic signals contributing to Earth's magnetic field.


Social unrest, riots, theft. What possible connection is there with the magnetic field enveloping our planet? This is what insurer Lloyd’s of London predicts for us if a very large electromagnetic storm on the sun were to hose the Earth with charged particles. The damage that could be done to our fundamental power infrastructure would cause massive disruption to society. A more complete understanding of our planet’s magnetic field and all the sources that feed into it might be a first step toward protecting ourselves.

Luckily, there’s a space mission for that! Launched in November 2013 by the European Space Agency, Swarm features three identical satellites circling the Earth in different orbits. These three separate points of view will allow scientists to pinpoint the contribution of the different known sources of our magnetic field. Movement in the Earth’s core (the geodynamo) is the principal player, but circulation in the ocean participates, too, as do phenomena in the crust and atmosphere. “Swarm will provide us with more information on the interactions between the magnetosphere, the ionosphere and the atmosphere—it’s a real puzzle!” says Gauthier Hulot, one of the mission’s leaders and an expert on geomagnetism at the Institute of Earth Physics of Paris (IPGP). Swarm promises to increase our knowledge on multiple levels: from processes taking place deep within the Earth to the terrestrial effects of space weather created by the sun.

Onboard each satellite are two magnetometers: one to measure the direction of Earth’s magnetic field, and a new, ultra high-precision instrument, the absolute scalar magnetometer developed by the CNES, to measure its intensity. The latter are much more precise than their predecessors used in the missions Ørsted and Champ.

The IPGP, in addition to participating in the magnetometer development, will be in charge of exploiting the data collected. The results sent back by Swarm’s trio of satellites will allow researchers to map the magnetic field with much higher resolution than ever before. Gauthier Hulot explains that, “Swarm is like a next-generation camera that lets us film Earth’s magnetic field in higher definition and for longer. It is helping us to know our magnetic shield better, and so, to better predict how it would react to a solar flare in our direction—but not to prevent it.”

The mission will also make it possible to recreate Earth’s protective magnetic envelope in the lab. Scientists studying topics as seemingly distant as climate change are eagerly awaiting the models developed from this information. “It is very difficult to establish a link between the evolution of Earth’s magnetic field and the climate,” Gauthier Hulot admits. “But it is possible or even probable that the protection given by the magnetic field has an influence on the atmosphere and, thus, the climate.” 

Swarm is busy tracking changes in the magnetic field over time, as well. In June 2014, results from the previous six months showed that, while the magnetic field had grown stronger over the southern Indian Ocean, for example, the magnetic shell protecting Earth from the powerful radiation of space is weakening, overall. Scientist are particularly concerned about the South Atlantic Anomaly, a spot where the magnetic field is much weaker; this is risky territory for satellites in low orbit.

  • Image: ESA/DTU Space"Snapshot" of the main magnetic field at Earth’s surface as of June 2014 based on Swarm data.

What should the world expect as the Earth’s magnetic field changes? Is there any way to prepare for the risk of major disturbances to our GPS and other technologies resulting from inclement space weather? And how, exactly, does Swarm do what it does?? The CNES, in partnership with MyScienceWork and the Bar des sciences, invites you to take part in the discussion, next Tuesday 20 January, at 7:30pm at the Café du Pont Neuf in Paris, or on Twitter via the hashtag #CNESTweetup. 


Front page image credit: ESA/ATG Medialab. "The magnetic field and electric currents near Earth generate complex forces that have immeasurable impact on our everyday lives. Although we know that the magnetic field originates from several sources, exactly how it is generated and why it changes is not yet fully understood. ESA’s Swarm mission will help untangle the complexities of the field."