Uploaded July 2026 | Updated September 2026, 2 weeks ago
ESA's Swarm mission comprises three satellites designed to measure Earth's magnetic field with exceptional precision. Among its many applications, Swarm can probe the electrical conductivity of Earth's deep interior – a property that cannot be measured directly, and that provides a unique window into the planet's composition. Electric currents flowing in the ionosphere and magnetosphere generate time-varying magnetic fields that penetrate deep into Earth.
These primary currents (Jp) and their associated magnetic field (Bp) induce secondary electric currents (Js) within Earth's conductive interior – principally the mantle and oceans. These secondary currents in turn generate a secondary magnetic field (Bs). By measuring both the primary and secondary magnetic signals – using Swarm satellites in orbit and a global network of ground-based observatories – scientists can map how electrical conductivity (σ) varies through Earth's layers and infer the composition of the deep interior.
Animation concept by Dr Alexander Grayver (Institute of Geophysics and Meteorology, University of Cologne).
Credits: European Space Agency (ESA)
Our main YouTube channel: youtube.com/@EuropeanSpaceAgency
We are Europe's gateway to space. Our mission is to shape the development of Europe's space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
Copyright information about our videos is available here: https://www.esa.int/ESA_Multimedia/Terms_and_Conditions
ESA's Swarm mission comprises three satellites designed to measure Earth's magnetic field with exceptional precision. Among its many applications, Swarm can probe the electrical conductivity of Earth's deep interior – a property that cannot be measured directly, and that provides a unique window into the planet's composition. Electric currents flowing in the ionosphere and magnetosphere generate time-varying magnetic fields that penetrate deep into Earth.
These primary currents (Jp) and their associated magnetic field (Bp) induce secondary electric currents (Js) within Earth's conductive interior – principally the mantle and oceans. These secondary currents in turn generate a secondary magnetic field (Bs). By measuring both the primary and secondary magnetic signals – using Swarm satellites in orbit and a global network of ground-based observatories – scientists can map how electrical conductivity (σ) varies through Earth's layers and infer the composition of the deep interior.
Animation concept by Dr Alexander Grayver (Institute of Geophysics and Meteorology, University of Cologne).
Credits: European Space Agency (ESA)
Our main YouTube channel: youtube.com/@EuropeanSpaceAgency
We are Europe's gateway to space. Our mission is to shape the development of Europe's space capability and ensure that investment in space continues to deliver benefits to the citizens of Europe and the world. Check out https://www.esa.int/ to get up to speed on everything space related.
Copyright information about our videos is available here: https://www.esa.int/ESA_Multimedia/Terms_and_Conditions
