European orbiter detects hints of volcanic activity on Mars

New evidence from the ExoMars Trace Gas Orbiter (TGO) suggests Mars may not be geologically dead deep inside, but merely sleeping. Data from the European spacecraft revealed signs of young volcanism on present-day Mars, including a steady release of hydrogen chloride in the martian atmosphere.

Hydrogen chloride detections

The ExoMars Trace Gas Orbiter (TGO) first reported hydrogen chloride gas in the martian atmosphere back in 2021. This gas is commonly found escaping from magmatic vents on Earth, leading researchers to wonder whether the same was happening on Mars.

It was early summer in the northern hemisphere of Mars when a team of researchers noticed spikes of hydrogen chloride where it should not have been, and during an odd season. This gas varies seasonally on Mars, reaching its maximum in the northern hemisphere winter, then mostly disappearing in the summer. Most of this variability appears to be linked with Mars’ dust and water cycles. Yet, there was one exception to this pattern, always in the same season and at the same place — above volcanic fissures on the flanks of the Alba Mons volcano, in early summer.

Research findings

An international research team’s new paper suggests that the release of hydrogen chloride comes from hot magma beneath the surface — a sign of dormant volcanism. The team’s analysis combined atmospheric measurements with geological observations. The data were collected by infrared spectrometers in TGO’s Atmospheric Chemistry Suite.

High-resolution images of the Alba Mons region from TGO’s CaSSIS camera also showed fresh, narrow fissures — some hundreds of metres long — alongside surface colour changes. Researchers suggested these fissures could act as channels for gas release, blocked by ice during winter and opening as temperatures rise in early summer.

Co-lead author Daniel Mège, a professor at the Space Research Centre of the Polish Academy of Sciences, said the findings indicate “Mars has retained enough internal heat to support volcanic activity until recently, and possibly still does”.

Broader context

Mars has the largest volcanoes in the solar system, but it is not known how active they are. Orbital imagery shows that some volcanoes appear to have been active within the last few million years, and seismometers have detected marsquakes — the earthquakes of Mars. Both facts point to the possibility of Mars being volcanically active. However, no new lava flows or eruptions have ever been observed.

Researchers also pointed to broader implications for Mars’ past climate and potential habitability. ESA said magmatic gases may have been more abundant in earlier periods, possibly contributing to a thicker atmosphere and warmer conditions. The team suggested that if magma interacts with groundwater, it could create warm subsurface environments that may be more favourable for life.

“Looking for martian life in the seeping fissures of the Alba Mons region would make a lot of sense,” Mège said, arguing that hydrothermal systems could provide energy and shelter for microorganisms.

ESA’s ExoMars Trace Gas Orbiter project scientist Colin Wilson said the results “may prove to be TGO’s greatest success yet”. The research paper, titled “Enigmatic HCl detections as a potential signature of igneous activity on Mars,” was published in Science Advances on 4 November 2026.

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Sources

• manoramayearbook.in: European orbiter detects hints of volcanic activity on Mars | ExoMars program | Manorama Yearbook
• spaceanddefense.io: European orbiter detects hints of volcanic activity on Mars - SPACE & DEFENSE

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