How an ice satellite became an unexpected tool for monitoring space weather
For almost a full 16 years, the European CryoSat satellite has been associated in public and scientific circles primarily with measuring changes in polar ice. Its basic task is to monitor the thickness of sea ice and changes in the ice sheets of Greenland and Antarctica, and those data have for years helped scientists understand how climate change is reshaping the polar regions. But at the beginning of 2026, that mission demonstrated another capability that at first glance seemed completely unexpected: it managed to record and scientifically usefully describe a geomagnetic storm caused by a powerful solar eruption.
At first glance, that sounds illogical. A satellite designed to observe ice sheets and floating sea ice should not have an important role in measuring disturbances in Earth’s magnetic field. And yet that is exactly what happened thanks to an innovative use of an instrument that was not originally intended for space weather science, but for the everyday management of the spacecraft. It is the so-called platform magnetometer, built in so that the satellite knows where it is, at what altitude it is flying, and how to properly orient its systems toward Earth.
CryoSat’s original mission remains ice, but it has gained a new scientific value
CryoSat is an ESA mission from the Earth Explorer programme launched on 8 April 2010. The spacecraft’s main instrument is the SIRAL radar altimeter, specially developed for precise monitoring of changes on the surface of ice sheets and sea ice. Thanks to that technology, CryoSat can record very small changes in surface height, allowing researchers to estimate ice loss, changes in Arctic floating ice, and processes taking place both above and below the ice surface. Over the years, that mission has grown into one of Europe’s key data sources for observing the cryosphere, but also for certain oceanographic analyses.
That is precisely why the development concerning the magnetometer is so interesting. The platform magnetometer on CryoSat was not conceived as a top-class scientific instrument like those on ESA’s Swarm mission, which is specifically dedicated to studying Earth’s magnetic field. It is first and foremost an operational sensor, part of the system that helps with the satellite’s stability and orientation. However, in recent years, experts have shown that the data from that sensor, when properly calibrated and processed, can have much broader value than originally envisaged.
At the end of 2025, CryoSat therefore received a remote software upgrade, without any physical intervention on the spacecraft itself. Such a step is especially important because this is a satellite that has long been operating beyond its initially designed lifetime. The upgrade enabled more precise processing of data from the magnetic sensor and the creation of a separate data package intended for scientific use. In other words, a signal that for years had been used mainly for the satellite’s “internal needs” began to be transformed into an additional source of information for researching external changes in Earth’s magnetic environment.
What is actually measured when a geomagnetic storm occurs
A geomagnetic storm occurs when an intensified flow of energy and particles from the Sun strongly disturbs Earth’s magnetosphere. Such events are most often associated with solar flares and coronal mass ejections, that is, enormous eruptions of ionised gas from the Sun’s outer atmosphere. When such a cloud reaches Earth, it can cause sudden changes in the magnetic field, intensify auroral activity, and create problems in satellite systems, navigation, radio communications, power grids, and other sensitive infrastructure.
The point is not that CryoSat has suddenly started doing the same work as Swarm, but that it can reliably register stronger external magnetic variations, especially those associated with space weather. This gives scientists an additional dataset from a different orbit and a different instrumental environment. In practice, that means a denser and more diverse observation network, which is particularly useful at times when Earth’s magnetic environment is changing rapidly.
ESA therefore continues to clearly separate the roles of the two missions. Swarm remains Europe’s main mission for the detailed study of the geomagnetic field, its internal structure, and its changes over time. CryoSat remains above all an ice mission. But in situations of strong external disturbances, its operational equipment can now be used as a valuable supplementary source of measurements. In a broader sense, this is an example of how space missions can gain a new function even after they have already been operating for years, without the need to launch an entirely new spacecraft for every additional task.
A powerful event on 18 January 2026 served as a real-world test
The real confirmation of that new capability came shortly after the upgrade. On 18 January 2026, a powerful X-class solar flare was recorded. According to data from NOAA’s Space Weather Prediction Center, solar region 4341 produced an X1.9 flare at 18:09 UTC. ESA then announced that the event was accompanied by a coronal mass ejection directed toward Earth. Models initially indicated a speed of around 1,400 kilometres per second, but the arrival of the wave at Earth after approximately 25 hours showed that it had travelled even faster, at around 1,700 kilometres per second.
The consequences did not remain only at the level of expert warnings. ESA states that the shower of high-energy particles on 19 January reached serious levels, and NOAA announced that on 19 January at 19:38 UTC, G4 levels were reached for the first time, marking a severe geomagnetic storm. ESA additionally warned that this was an event capable of affecting satellites in orbit, power grids, and aviation. At the same time, auroras were visible at unusually low geographic latitudes across Europe, and reports and photographs were also arriving from other parts of the world.
It was precisely at such a dynamic and scientifically very demanding moment that CryoSat showed that its new role was not merely a technical curiosity. Over the course of approximately three days, the satellite collected data that helped assess the intensity of the geomagnetic storm. According to ESA’s description, those data proved to be of good quality and complementary to Swarm’s measurements. In other words, CryoSat did not replace the specialised magnetic mission, but it did provide an additional layer of observations that helps create a more precise picture of the event.
Why the upgrade matters beyond a single storm
The value of this innovation is not only that one ice satellite “caught” one geomagnetic storm. More important is that it has shown how existing space infrastructure can be intelligently upgraded and used in a way that creates new scientific value without the cost of developing and launching a new mission. At a time when space programmes are becoming ever more expensive and the need for data is growing, such flexibility is becoming an important argument in favour of extending the lives of active satellites.
CryoSat is a good example precisely because it is a mission that long ago outlived its original expectations. ESA still uses it as a key tool for understanding polar changes, and now an additional role is opening up for it in monitoring space weather. Such a development shows how modern satellite technology is not rigid: the same platform, with changes in software and data processing, can produce scientifically relevant information for several different disciplines.
This is especially important for the community that studies geomagnetic disturbances. Earth’s magnetic field is neither constant nor calm. It is influenced by processes deep within Earth’s core, currents in the ionosphere and magnetosphere, and also by changes associated with solar activity. The more high-quality measurements there are from low orbit, the easier it is to separate those influences and build more reliable models. During fast and powerful events, such as the storm in January 2026, every additional relevant measurement can help in understanding the arrival time, intensity, and spatial distribution of the disturbance.
CryoSat and Swarm: two different missions that now complement each other
The Swarm mission, consisting of three satellites, remains ESA’s main tool for studying the geomagnetic field and the electric field in the atmosphere. From the beginning, its scientific task was aimed precisely at Earth’s magnetic environment, which is why both the instruments and the data processing were designed for that type of research. CryoSat, by contrast, was never developed with that as its primary purpose.
And yet it is precisely in that difference that a new advantage lies. When two systems with different original purposes provide a comparable and complementary signal during the same event, scientists gain a more robust basis for verifying models and calibrating data. ESA had previously published CryoSat’s magnetic datasets for the needs of the community associated with Swarm, and the more recent software upgrade shows that this cooperation can be raised to a higher level. This is an important shift because we are no longer talking only about historical or retrospectively processed series, but also about better use of an active spacecraft at the moment of real space disturbances.
In that context, NanoMagSat is also often mentioned, a new ESA Scout mission intended for measuring Earth’s magnetic field and monitoring hazards associated with space weather. This opens up a broader picture of the future European architecture: Swarm as a dedicated and proven magnetic mission, CryoSat as a successfully repurposed supplementary source, and NanoMagSat as the next step toward a new generation of smaller and more agile satellites. For the scientific community, this means more data, greater system resilience, and better coverage at moments when the Sun becomes especially active.
What this story says about the future of satellite missions
The case of CryoSat is interesting also because it breaks the old notion that after launch, a satellite remains forever limited to the task for which it was built. Of course, its design, orbit, and instruments set clear limits. But software development, signal processing, and advanced calibration methods can today extract significantly more from existing systems than they could ten or fifteen years ago. In that sense, CryoSat is not just a story about ice and magnetic storms, but also about how the value of a mission can increase over the years.
It is important, however, to avoid exaggeration. CryoSat has not become a new specialised magnetic observatory in orbit, nor has its original mission been changed. Its key role remains the monitoring of ice sheets, sea-ice thickness, and changes in the polar oceans. But the fact that one operational component, with an intelligent upgrade, can become a credible source of scientific data shows how the boundaries between a “service” instrument and a “scientific” instrument are becoming increasingly flexible today.
For the wider public, perhaps the most interesting aspect is precisely that paradox: a satellite that observes ice expanses helps scientists understand the effects of solar eruptions. For experts, however, another message is even more important. When a strong geomagnetic storm occurs, every additional high-quality measurement point can have real value for science, operational monitoring, and long-term risk modelling. If that can be achieved by upgrading an existing satellite, then it is a rare success story combining cost efficiency, engineering ingenuity, and scientific benefit.
That is precisely why CryoSat’s new role goes beyond an interesting news item from the world of space. It shows how long-lived missions can be adapted to new needs and how additional value can be extracted from systems that already exist at the moment when it is needed most. In an era of heightened solar activity, a growing number of satellites, and society’s increasing dependence on sensitive technological infrastructure, such a capability is no longer merely a convenient bonus, but is becoming an important part of a broader strategy for monitoring and understanding changes that come directly from space and affect life on Earth.
Sources:- ESA – official CryoSat mission page with data on launch, purpose, and the main instrument https://www.esa.int/Applications/Observing_the_Earth/FutureEO/CryoSat- ESA Earth Online – overview of the CryoSat mission and its role in measuring sea-ice thickness and ice sheets https://earth.esa.int/eogateway/missions/cryosat- ESA – report on space weather in January 2026, with data on the 18 January flare, the CME arrival, and the consequences on Earth https://www.esa.int/Space_Safety/Space_weather/ESA_monitoring_January_2026_space_weather_event- NOAA SWPC – official announcement on the X1.9 solar flare of 18 January 2026 https://www.swpc.noaa.gov/news/x-class-flare-activity-observed-18-january-2026- NOAA SWPC – official announcement on reaching the G4 geomagnetic storm level on 19 January 2026 https://www.swpc.noaa.gov/news/g4-severe-geomagnetic-storm-levels-reached-19-jan-2026- NOAA SWPC – explanation of geomagnetic storms and the effects of magnetosphere disturbances https://www.swpc.noaa.gov/phenomena/geomagnetic-storms- ESA – overview of the Swarm mission, Europe’s main mission for studying Earth’s magnetic field https://earth.esa.int/eogateway/missions/swarm- ESA – announcement on the development of the NanoMagSat mission as a future Scout mission for measuring Earth’s magnetic field https://www.esa.int/Applications/Observing_the_Earth/FutureEO/NanoMagSat_and_Tango_Scout_missions_get-go-ahead
Find accommodation nearby
Creation time: 4 hours ago