Flying through the biggest solar storm ever recorded

Before each ESA launch, mission teams go through a rigorous simulation phase that rehearses a satellite’s first moments in space while preparing mission control for any anomalies. Since mid-September, teams at ESA’s European Space Operations Center (ESOC) in Darmstadt, Germany, have been immersed in simulations of Sentinel-1D, scheduled for launch on 4 November 2025.

To model one of the most extreme scenarios, simulation officials took inspiration from the infamous Carrington event of 1859, which was the strongest geomagnetic storm ever recorded. The exercise replicated the effects of a destructive solar storm on satellite operations to test the team’s ability to respond without satellite navigation and under severe electronic interference.

“Should such an event occur, there is no good solution. The goal will be to keep the satellite safe and limit the damage as much as possible,” says Thomas Ormston, deputy spacecraft operations manager for Sentinel-1D.

The mission included a rare activation by ESA’s Space Weather Office of its Space Safety Centre, which is scheduled to be inaugurated in 2022 as part of ESA’s increased commitment to space safety. ESA’s Space Debris Office and spacecraft operations managers from other ESA Earth-orbiting missions also joined the exercise to enhance realism, simulate cross-mission impacts and coordination.

get caught in the evil wave

The time is 22:20 and everything is going according to plan. After a successful launch and separation, mission control waits for satellite signal acquisition. A few minutes later, a noisy transmission reaches mission control. Something is wrong.

The spacecraft, along with others in orbit, is hit by a solar flare. Traveling at the speed of light, this electromagnetic wave has reached our planet just eight minutes after its eruption from the Sun.

The simulation team modeled a massive, X45-class flare that disrupts radar systems, communications and tracking data with intense X-ray and ultraviolet radiation. Galileo and GPS navigation functionalities are now offline, while ground stations, particularly in polar regions, have lost tracking capabilities due to extreme radiation levels.

Moments later, Earth is hit by a second wave, this time composed of high-energy particles including protons, electrons, and alpha particles. These particles, accelerated to near-light speed, have taken 10 to 20 minutes to reach our planet, and are beginning to irritate onboard electronics with bit flips and potentially permanent failures.

Gustavo Baldo Carvalho, Sentinel-1D lead simulation officer, says, “The solar flare took the team members by surprise. But once they calmed down, they realized that the countdown had begun. In the next 10 to 18 hours, there will be a coronal mass ejection, and they had to be prepared for it.”

CME ride

15 hours after the solar flare, the third and most destructive phase began: a giant coronal mass ejection – a hot plasma of charged particles – struck Earth traveling at 2000 km/s and triggered a catastrophic geomagnetic storm.

On land, beautiful auroras were visible as far south as Sicily, while the storm demolished power grids and provoked damaging surges of electrical current in long metal structures such as power lines and pipelines.

Satellites also had to struggle in space. The storm caused Earth’s atmosphere to swell, causing satellites in low Earth orbit to drag and move out of their normal trajectories. Mission controllers faced multiple warnings of space debris and collisions with other spacecraft.

Jorge Amaya, Space Weather Modeling Coordinator at ESA, says, “If such a storm occurs, satellite drag could increase by up to 400% with local peaks in atmospheric density. This not only affects collision risks, but also reduces satellite lifetime due to increased fuel consumption to compensate for orbit decay.”

“An event of such magnitude would severely degrade the quality of the conjunction data, making collision predictions difficult to interpret as probabilities change rapidly. In this context, decision-making under significant uncertainties becomes a delicate balance, where an evasive move to reduce the risk of one potential collision may slightly increase the risk of another,” explains Jan Szyminski of the ESA Space Debris Office.

Radiation levels also increased, causing damage to electronics and materials. Single-event malfunctions began to occur more frequently, causing system wear and shortened operating lives. GNSS signals deteriorated further, star trackers went blind and battery charging incidents added to the chaos.

George says, “The extreme flux of energy emitted by the Sun could damage all of our satellites in orbit. Satellites in low-Earth orbit are usually better protected from space threats by our atmosphere and our magnetic field, but a blast of the magnitude of the Carrington event would not leave any spacecraft unharmed.”

Training for the ‘big one’

“This exercise has been an opportunity to expand a simulation training campaign and involve many other stakeholders in ESOC, covering all types of missions and operational teams. Conducting it in a controlled environment gave us valuable insights into how we can better plan, approach and respond when such an incident occurs. The key thing is that it is not a question of If This will happen but When?”says Gustavo.

ESA’s Space Security Center played a central role in the exercise and is a vital asset in Europe’s preparations for extreme solar storms. The simulation will provide important insights for the formation of European-wide space weather operational services, helping to refine processes and improve resilience.

“Simulating the impact of such an event is similar to predicting the impact of a pandemic: we will feel its real impact on our society only after the event, but we must be prepared and plan to react at a moment’s notice. This exercise was the first opportunity to address such a large event and incorporate the ESA Space Weather Office’s response into established ESA operations,” says George.

Thomas concluded, “The scale and diversity of the impacts pushed us and our systems to the limit, but the team mastered the challenge and taught us that if we can manage this we can manage any real-life contingency.”

infrastructure for the future

In addition to testing the resilience of space weather in operation, such simulations highlight the urgent need to improve the European ability to predict space weather events.

ESA’s Space Security Program is developing distributed space weather sensor systems (D3S). This series of space weather satellites and hosted payloads will monitor various space weather parameters around Earth and provide an unmatched source of data, ready to protect Europe’s citizens and critical infrastructure.

Beyond Earth, ESA’s Vigil mission will introduce a revolutionary approach by observing the ‘side’ of the Sun from Lagrange Point 5, revealing continued insights into solar activity.

Launching in 2031, Vigil will detect potentially dangerous solar events before they are visible from Earth, giving us advance knowledge of their characteristics and precious time to protect spacecraft and ground infrastructure.