Data from the ExoMars Trace Gas Orbiter detected hydrogen chloride above volcanic fissures in the Alba Mons region, suggesting possible dormant volcanism 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 orbiter revealed signs of young volcanism on present-day Mars, including a steady release of hydrogen chloride in the martian atmosphere.
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 gas was detected above volcanic fissures on the flanks of the Alba Mons volcano in early summer in the northern hemisphere of Mars.
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.
Hydrogen chloride 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.
High-resolution images of the Alba Mons region from TGO’s CaSSIS camera 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.
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.
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.
The findings suggest Mars may retain enough internal heat to support volcanic activity until recently, and possibly still does. Researchers also pointed to broader implications for Mars’ past climate and potential habitability, noting that magmatic gases may have been more abundant in earlier periods, possibly contributing to a thicker atmosphere and warmer conditions. If magma interacts with groundwater, it could create warm subsurface environments that may be more favourable for life.
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This article was drafted with AI assistance and checked against the sources above. Company claims are reported as claims. Cover image is AI-generated.
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