What happened when a solar superstorm hit Mars?

• In May 2024, a solar superstorm hit Mars. Two European Space Agency spacecraft at Mars observed the impacts, and now a new study has been released.
• The storm triggered the largest electron surge ever recorded in Mars’ upper atmosphere. It dramatically boosted charged particles.
• Both orbiters also recorded glitches in their computers. This is an expected result of solar storms that also affect satellites in Earth orbit.

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ESA published this original story on March 5, 2026. Edits by EarthSky.

What happened when a solar superstorm hit Mars?

In May 2024, Earth was hit by the biggest solar storm recorded in over 20 years. It sent our planet’s atmosphere into overdrive, triggering shimmering auroras that were seen as far south as Mexico. This storm also hit Mars. And the European Space Agency’s two Mars orbiters – Mars Express and ExoMars Trace Gas Orbiter (TGO) – were in the right place at the right time. A radiation monitor aboard TGO picked up a dose equivalent to 200 ‘normal’ days in just 64 hours.

A new peer-reviewed study published on March 5, 2026, in the journal Nature Communications now reveals in greater depth how this intense, stormy activity affected the red planet.

ESA Research Fellow Jacob Parrott was the lead author of the study. Parrott said:

The impact was remarkable: Mars’ upper atmosphere was flooded by electrons. It was the biggest response to a solar storm we’ve ever seen at Mars.

The superstorm caused a dramatic increase in electrons in two distinct layers of Mars’ atmosphere. This occurred at altitudes of around 110 and 130 km (68 and 80 miles), with numbers rising by 45% and a whopping 278%, respectively. This is the most electrons we’ve ever seen in this layer of Martian atmosphere. Parrott added:

The storm also caused computer errors for both orbiters. It’s a typical peril of space weather, as the particles involved are so energetic and hard to predict. Luckily, the spacecraft were designed with this in mind, and built with radiation-resistant components and specific systems for detecting and fixing these errors. They recovered fast.

Pioneering a new technique

To investigate the superstorm’s impact on Mars, Parrott and colleagues used a technique ESA is currently pioneering. It’s known as radio occultation.

First, Mars Express beamed a radio signal to TGO at the very moment it was disappearing over the Martian horizon. As TGO vanished, the radio signal was bent (refracted) by the various layers of Mars’ atmosphere before being picked up by the orbiter. This allowed scientists to glean more about each layer. The researchers also used observations from NASA’s MAVEN mission to confirm the electron densities.

Colin Wilson is an ESA project scientist for Mars Express and TGO, and co-author of the study. Wilson said:

This technique has actually been used for decades to explore the solar system, but using signals beamed from a spacecraft to Earth. 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, which usually use those radios to beam data between orbiters and rovers. It’s great to see it in action.

ESA uses orbiter-to-orbiter radio occultation routinely at Earth. And it plans to use it more regularly in future planetary missions.

Different worlds, different weather

Earth and Mars experienced this superstorm differently, and it highlights the differences between the two worlds.

At Earth, the response of the upper atmosphere was more muted, thanks to the shielding effect of Earth’s magnetic field. As well as deflecting a lot of solar storm particles away from Earth, the magnetic field also diverted some toward Earth’s poles, where they caused the sky to light up with auroras.

While their differences can make it tricky to compare planets directly, understanding how solar activity impacts the residents of the solar system – in other words, space weather forecasting – is hugely important. At Earth, solar storms can be dangerous and damaging for astronauts and equipment up in space. Plus, they can disrupt our satellites and systems (power, radio, navigation) further down.

However, studying space weather is difficult, as the sun throws out radiation and material erratically, making targeted measurements largely opportunistic. Parrot said:

Fortunately, we were able to use this new technique with Mars Express and TGO just 10 minutes after a large solar flare hit Mars. Currently we’re only performing two observations per week at Mars, so the timing was extremely lucky.

Analyzing the aftermath

Parrott and colleagues captured the aftermath of three solar events. They were all part of the same storm, but different in terms of what they throw out into space and how they do it. One was a flare of radiation, one was a burst of high-energy particles, and one was an eruption of material known as a coronal mass ejection (CME).

Together, these events sent fast-moving, energetic, magnetized plasma and X-rays flooding towards Mars. When this barrage of material hit the planet’s upper atmosphere, it collided with neutral atoms and stripped away their electrons, causing the region to fill up with electrons and charged particles. Wilson said:

The results improve our understanding of Mars by revealing how solar storms deposit energy and particles into Mars’s atmosphere. It’s important as we know the planet has lost both huge amounts of water and most of its atmosphere to space, most likely driven by the continual wind of particles streaming out from the sun.

But there’s another side to it: the structure and contents of a planet’s atmosphere influence how radio signals travel through space. If Mars’s upper atmosphere is packed full of electrons, this could block the signals we use to explore the planet’s surface via radar, making it a key consideration in our mission planning … and impacting our ability to investigate other worlds.

Bottom line: What happened when a solar superstorm hit Mars? In May 2024, the sun released a powerful X flare that caused spacecraft to glitch … and more. Read all about it here.

Source: Martian ionospheric response during the may 2024 solar superstorm

Via ESA

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