As geomagnetic skies lit up above Earth in May 2024, Mars faced the same blast with far less protection, and ESA spacecraft were already in position when the Sun’s violence arrived.
That contrast turned routine monitoring into a rare scientific record, as instruments tracked interference, charged particles, and a fast-changing upper atmosphere. Seen from Earth as May 2024 auroras, the event reached Mars as a solar particle burst wrapped in extreme space weather, pushing orbiters, radar links, and atmospheric models toward the edge in a single surge, then
May 2024 brought auroras to Earth and turmoil to Mars
In May 2024, auroras spread far beyond their usual latitudes on Earth, lighting skies well outside the poles. The spectacle came from the Sun-facing region AR3664, which launched an X2.9 solar flare and a coronal mass ejection toward the inner Solar System.
At nearly the same time, Mars was struck by the same disturbance. What looked dazzling from Earth became a severe geomagnetic storm linked to a broad polar lights expansion, while the Red Planet faced the blast with far less natural shielding.
How Mars Express and TGO caught the storm as it arrived
Mars Express and ExoMars Trace Gas Orbiter were in position when the outburst reached Mars. Working as ESA orbiters, they began observing about 10 minutes after arrival, a narrow gap that let researchers follow the first moments instead of reconstructing them later.
That timing gave the team a rare, near-live record of the event. The study ties this rapid storm detection to radiation roughly equal to 200 normal days packed into 64 hours of exposure, showing how much can change around Mars in less than three days.
It’s only in the past five years or so that we’ve started using it at Mars between two spacecraft, such as Mars Express and TGO. It’s great to see it in action.
Colin Wilson, ESA project scientist for Mars Express and TGO
A radio signal crossing the Martian horizon told the story
The clearest clue came from a link between the two spacecraft as one slipped behind Mars from the other’s view. This radio occultation method tracks how the signal bends and slows while crossing different atmospheric layers near the planet’s horizon.
That setup is still unusual at Mars, which gives the result extra weight. From the distorted transmission, scientists extracted electron density data and compared it with MAVEN support from NASA’s orbiter, building a fuller picture of the ionosphere during the storm.
Mars took a harsher hit than Earth did
Measurements showed a sharp surge in charged particles above Mars during the storm. The recorded upper atmosphere response reached a 45 percent increase and a 278 percent increase across measurements taken at 110 km and 130 km above the surface.
Radiation rose at the same time, and both ESA spacecraft reported temporary computer errors before recovering. Earth saw the same solar blast, yet its global magnetic field diverted many particles toward the poles, while Mars absorbed far more of the hit directly.
Mars’s upper atmosphere was flooded by electrons. It was the biggest response to a solar storm we’ve ever seen at Mars.
Jacob Parrott, ESA Research Fellow and lead author of the study
The findings matter for radar, spacecraft, and life around Mars
These results feed directly into how Mars missions are designed and run today. During intense solar activity, radar signal disruption can blur subsurface sounding, and teams may need different mission operations to protect instruments, timings, and communications around the planet.
The study reaches further than hardware alone. By linking present-day storms to astronaut safety concerns and to long-term atmospheric loss, ESA and its partners gain fresh evidence on how the Sun helped strip Mars over billions of years.
