ESA’s CryoSat-2 satellite, designed and operated to measure polar ice thickness, recorded significant disruptions during the extreme geomagnetic storm that struck Earth in May 2024. The event, classified at the highest G5 level on the NOAA Space Weather Prediction Center scale, degraded orbit calculations and sea-level data products from multiple satellite missions for days. What began as a chain of solar eruptions between May 7 and May 11 ended up testing the limits of Earth-observing infrastructure in low orbit, and CryoSat-2’s experience reveals a tension between climate monitoring continuity and growing space weather risks.
Solar Eruptions Triggered the Strongest Storm in Years
The magnetic disturbance that rattled satellites and lit up auroras across mid-latitudes began on May 10, 2024, according to the U.S. Geological Survey’s Geomagnetism Program. USGS magnetometer stations across the country recorded the effects as the storm rapidly intensified to G5/extreme, the most severe rating on the NOAA SWPC scale. That classification had not been applied to a geomagnetic event in roughly two decades, underscoring how unusual the solar activity was.
The storm’s origins traced back to a sequence of flares and coronal mass ejections that erupted from the Sun between May 7 and 11. Modeling work using the MAGE and GAMERA frameworks showed how those CMEs compressed and distorted Earth’s magnetosphere, heating and expanding the upper atmosphere. That expansion is the mechanism that creates problems for satellites: denser air at orbital altitudes increases drag, while ionospheric disturbances corrupt the signals spacecraft rely on for precise positioning and timing.
CryoSat-2’s Orbit Errors Persisted for Days
CryoSat-2 was hit particularly hard because of how it measures sea level and ice elevation. The satellite operates as a single-band radar altimeter that depends on modeled ionospheric delay corrections rather than directly measuring the ionosphere with dual-frequency signals. When the storm scrambled the ionosphere, those models failed to keep pace with real conditions. The result was large orbit errors in near-real time that persisted for several days, degrading the quality of sea-level anomaly products distributed to users.
The NOAA assessment noted that several altimetry missions experienced similar orbit calculation failures during the storm, but CryoSat-2’s single-band design made it especially vulnerable. Dual-frequency altimeters on newer missions can compare signals at two wavelengths to directly estimate ionospheric delay; CryoSat-2 lacks that capability and must rely on external models that assume a relatively stable ionosphere. During a G5 storm, that assumption breaks down and the corrections can be off by enough to contaminate subtle sea-level signals.
For researchers and operational users who depend on near-real-time sea-level data from platforms like NOAA’s CoastWatch portal, the disruption was more than a technical curiosity. Regional services, including Caribbean monitoring efforts and the Pacific Islands OceanWatch system, draw on satellite altimetry to track mesoscale ocean features, support marine forecasts, and monitor long-term climate trends. Days of compromised data during an active hurricane season or a critical melt period in the polar regions could affect everything from storm surge modeling to fisheries management.
In practice, data centers flagged the affected products and advised caution in their use, but that still left a gap in the seamless time series that climate scientists and operational forecasters prefer. For climate applications, a few days of degraded measurements may be tolerable if they are well documented and can be filtered or reprocessed later. For real-time decision-making, such as anticipating coastal flooding or routing ships around strong currents, the loss of accuracy at the moment it is needed can be far more consequential.
ICESat-2 Entered Safe Hold From the Same Storm
NASA’s ICESat-2, another low Earth orbit satellite that measures ice sheet elevation using laser altimetry, suffered even more direct consequences. The May 2024 storms forced ICESat-2 into safe hold, a protective mode that suspends science operations to preserve the spacecraft and its instruments. Increased atmospheric drag from the expanded upper atmosphere altered the satellite’s orbit and complicated its pointing and ranging geometry, creating issues that mission managers expected to resolve by mid-June 2024.
The parallel disruptions to CryoSat-2 and ICESat-2 expose a systemic vulnerability. Both satellites are central to tracking ice loss in Greenland and Antarctica, measurements that feed directly into sea-level rise projections and climate models. When a single space weather event can sideline or degrade both missions simultaneously, the scientific community loses its primary eyes on polar ice at the same time. No backup constellation exists to fully replace those observations in real time, and reprocessing after the fact cannot recover data that were never collected.
This vulnerability is not only about gaps in time series. Ice sheets can undergo rapid changes (such as calving events or sudden accelerations in outlet glaciers) that scientists hope to capture in detail. If a major geomagnetic storm coincides with one of those episodes, the opportunity to observe the event with high precision could be lost. That possibility adds urgency to discussions about building redundancy into future climate-monitoring fleets and hardening them against space weather.
An Ice Satellite’s Unexpected Role in Space Weather
CryoSat-2 was never built to study geomagnetic storms. Launched in 2010, its radar altimeter was engineered to measure the first returning energy in radar echoes bouncing off ice and ocean surfaces, extracting subtle changes in elevation over time. The platform magnetometer onboard is an operational instrument, used for attitude control, and was not originally intended to produce scientific data about Earth’s magnetic field.
Yet the May 2024 storm highlighted how even “non-science” sensors can become valuable space weather tools. As the geomagnetic disturbance intensified, CryoSat-2’s magnetometer registered strong fluctuations in the local field that engineers initially monitored to safeguard the spacecraft. Those same measurements can help reconstruct the temporal and spatial structure of the storm from low Earth orbit, complementing ground-based magnetometers and dedicated space weather missions.
Engineers and scientists are now exploring how to better exploit such ancillary measurements. With appropriate calibration and processing, operational magnetometers on Earth-observing satellites could contribute to real-time assessments of geomagnetic activity and upper-atmospheric conditions. That information, in turn, could feed into models that predict drag and ionospheric disturbances, improving the orbit solutions and data quality for the very satellites carrying the sensors.
Balancing Climate Monitoring and Space Weather Risk
The May 2024 storm serves as a stress test for the climate-monitoring infrastructure that governments and researchers increasingly rely on. CryoSat-2’s orbit errors and ICESat-2’s safe-hold episode show that missions designed around long-term stability can still be vulnerable to rare but powerful bursts of solar activity. As the satellite fleet ages and new missions are planned, agencies face a trade-off between pushing for ever more precise measurements and ensuring resilience against extreme space weather.
Several lessons emerge from CryoSat-2’s experience. First, reliance on ionospheric models without direct measurements leaves single-frequency missions exposed during storms. Future altimeters may need built-in redundancy, through dual-frequency operation, cross-calibration with GNSS signals, or partnerships with dedicated ionospheric sensors, to maintain accuracy when the upper atmosphere is disturbed. Second, operational data systems must be able to rapidly flag, characterize, and if possible correct storm-induced errors so that users understand the limitations of the data in real time.
Finally, the episode underscores the value of treating climate and space weather monitoring as interconnected rather than separate domains. Satellites like CryoSat-2 and ICESat-2 are launched to track ice and sea level, but their performance is tightly coupled to the behavior of the Sun and Earth’s magnetosphere. Designing future missions with that coupling in mind, through hardened electronics, flexible operations concepts, and smarter use of onboard sensors, could help ensure that the next extreme storm does not blind the world’s primary instruments for watching a changing planet.
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*This article was researched with the help of AI, with human editors creating the final content.
