Solar Superstorm Causes Dramatic Atmospheric Swelling on Mars

Daily Technology

06/03/2026

In May 2024, a powerful solar superstorm erupted from the Sun, impacting not only Earth but also Mars. This event, originating from the active sunspot region AR3664, sent a massive surge of charged particles and radiation hurtling through space. While Earth experienced one of the largest geomagnetic storms in decades, the effects on Mars provided scientists with a unique opportunity to study solar weather's influence on another planet.

Key Takeaways

A solar superstorm in May 2024 caused Mars's lower ionosphere to expand dramatically, nearly tripling its typical size.
The event flooded Mars's upper atmosphere with electrons, marking the most significant observed response to a solar storm on the Red Planet.
Data from the European Space Agency's Mars Express and ExoMars Trace Gas Orbiter (TGO) were crucial for the study, despite temporary glitches caused by the storm.

The Solar Superstorm Event

The solar superstorm was triggered by an X2.9 class solar flare and subsequent coronal mass ejections (CMEs) from the sunspot region AR3664. This region is known for producing intense solar activity. The CMEs, eruptions of plasma from the Sun's corona, propelled vast amounts of magnetized material towards the inner solar system. While Earth's magnetosphere absorbed much of this energy, leading to significant geomagnetic disturbances, Mars, lacking a global magnetic field, experienced a different kind of interaction.

Studying Mars's Atmospheric Response

Researchers utilized data from the European Space Agency's (ESA) Mars Express and ExoMars Trace Gas Orbiter (TGO) to analyze the storm's impact on Mars. The study, published in Nature Communications, employed a radio occultation technique. This involved Mars Express beaming a radio signal to TGO as it passed over the Martian horizon. As the signal traversed different atmospheric layers, its bending provided data on the density of charged particles.

Dramatic Atmospheric Expansion

The analysis revealed that the solar storm caused the lower layer of Mars's ionosphere to swell to nearly three times its normal size. This dramatic expansion is attributed to the influx of energetic electrons and solar plasma. Scientists believe these particles collided with neutral atoms in the upper atmosphere, stripping away electrons and significantly increasing the concentration of charged particles. Lead author Jacob Parrott described the event as the "biggest response to a solar storm we've ever seen at Mars."

Implications for Understanding Mars

This event offers valuable insights into how solar dynamics shape planetary atmospheres. Mars is known to have lost a significant portion of its atmosphere and water to space over billions of years, with the solar wind being a primary driver. Understanding how solar storms inject energy and particles into its atmosphere is crucial for comprehending this atmospheric loss. Despite the storm causing temporary computer errors on both ESA orbiters, their radiation-resistant designs allowed for recovery and data collection, providing a rare and important glimpse into the Red Planet's dynamic atmospheric behavior.

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