Since August 2025, Swarm A has been among the satellites observed by ARCA Dynamics as part of a service evaluation supported by the European Space Agency (ESA) under its Space Safety Programme (S2P).
Launched on November 22, 2013, ESA’s Swarm mission has quietly revolutionized our understanding of Earth’s magnetic field. Over the past eleven years, the trio of satellites (Swarm Alpha, Bravo, and Charlie) has delivered the most precise and continuous measurements of the planet’s geomagnetic environment ever recorded from low Earth orbit.
A Decade of Magnetic Insights
Swarm was designed to unravel the complexities of Earth’s magnetic field, which shields life from harmful solar and cosmic radiation. By measuring both vector and scalar components, the satellites have helped scientists decode the contributions of the planet’s core, mantle, crust, oceans, ionosphere, and magnetosphere.
Some of its most impactful findings include:
- Improved models of the geodynamo, the turbulent flow of molten iron in Earth’s outer core that generates the magnetic field
- Tracking the migration of the magnetic poles, especially the rapid drift of the North Magnetic Pole toward Siberia
- Refining space weather forecasts, crucial for satellite operations and communication systems
- Mapping electric currents in the ionosphere and magnetosphere, enhancing our understanding of solar-terrestrial interactions
The South Atlantic Anomaly: A Growing Concern
Swarm’s latest contribution, published in Physics of the Earth and Planetary Interiors, focuses on the South Atlantic Anomaly (SAA), a region where Earth’s magnetic field is significantly weaker. Between 2014 and 2025, Swarm data revealed that the SAA has expanded by nearly 1% of Earth’s surface area, with its minimum intensity dropping from 22,430 nT to 22,094 nT.
This weakening exposes satellites to higher radiation levels, increasing the risk of system failures. The anomaly’s evolution is linked to reversed flux zones at the core-mantle boundary, regions where magnetic field lines re-enter the Earth instead of emerging. One such zone is drifting westward beneath Africa, intensifying the anomaly and reshaping our models of core dynamics.
Reference: “Core field changes from eleven years of Swarm satellite observations” by C.C. Finlay, C. Kloss, N. Gillet. Published in Physics of the Earth and Planetary Interiors, 2025. Available on ScienceDirect.
Eyes On is ARCA Dynamics’ editorial series spotlighting the satellites we observe closely.
This article is part of Eyes On, a recurring series in which ARCA Dynamics explores the missions included in its portfolio of actively monitored space assets. Within this framework, ARCA Dynamics is deploying and refining its space-based Space Surveillance and Tracking (SST) service, which includes direct in-orbit monitoring capabilities. These activities, part of a service evaluation supported by ESA’s Space Safety Programme (S2P), contribute to the safe and sustained operation of space missions in low Earth orbit, supporting ESA’s broader goals of orbital resilience and European competitiveness in space safety.
Swarm A continues to deliver vital data from orbit, and we wish it a long, healthy, and secure journey ahead.