A powerful solar superstorm that struck Earth in May 2024 not only triggered spectacular auroras across the planet but also caused unexpected computer errors on spacecraft orbiting Mars, according to a new study published in Nature Communications.
The storm, the strongest recorded in more than two decades, sent a barrage of charged particles and radiation racing through the Solar System after a major solar flare and a coronal mass ejection erupted from the Sun.
While Earth experienced dazzling auroras seen as far south as Mexico, Mars faced a very different and far more intense impact.
Scientists from the European Space Agency (ESA) discovered that the solar storm flooded the upper atmosphere of Mars with charged particles, dramatically altering its structure and temporarily disrupting spacecraft systems.
At the time of the event, ESA’s orbiters Mars Express and the ExoMars Trace Gas Orbiter (TGO) were perfectly positioned to capture the storm’s effects.
Radiation monitors aboard TGO recorded an enormous surge in radiation, equivalent to 200 days of normal exposure in just 64 hours. The energetic particles also caused brief computer glitches in both orbiters, a common risk during powerful solar storms.
“The impact was remarkable,” said ESA research fellow Jacob Parrott, lead author of the study. “Mars’s upper atmosphere was flooded with electrons. It was the biggest response to a solar storm we’ve ever seen at Mars.”
Measurements revealed that electron levels surged dramatically in two layers of the Martian atmosphere located around 110 km and 130 km above the surface. Electron densities increased by 45% in one layer and an astonishing 278% in the other, the highest levels ever observed in those regions.
Despite the disruption, both orbiters recovered quickly thanks to radiation-resistant electronics and automated systems designed to detect and correct errors.
To study the phenomenon, researchers used a technique known as radio occultation, in which one spacecraft transmits radio signals to another as it passes behind the planet.
As the signal travels through Mars’s atmosphere, it bends slightly depending on the density of particles in each layer. By analysing this bending, scientists can map atmospheric conditions in detail.
Data from Nasa’s MAVEN spacecraft helped confirm the massive spike in electrons.
The event also highlighted the stark differences between Earth and Mars. Earth’s strong magnetic field shields the planet from many solar particles, redirecting them toward the poles where they produce auroras. Mars, however, lacks a global magnetic field, leaving its atmosphere far more exposed to solar storms.
Understanding these events is critical for future missions. High electron concentrations can disrupt radar signals and communication systems, potentially affecting spacecraft exploring Mars.
The findings offer new insight into how solar storms interact with planetary atmospheres, and how space weather can cause chaos millions of kilometres away from Earth.
