Data from the European Space Agency’s ExoMars Trace Gas Orbiter (TGO) have revealed the presence of hydrogen chloride gas escaping through fissures in the Alba Mons region of Mars. The detection, made during the planet’s summer season, is interpreted by scientists as a sign that the Red Planet’s volcanoes are not extinct but merely dormant.
Observations by the Trace Gas Orbiter
The TGO, while monitoring the Martian atmosphere, recorded spikes of hydrogen chloride (HCl) in the northern hemisphere during the summer months—an interval when the gas is normally absent. On Mars, HCl concentrations usually peak in winter and fade in summer as part of the water‑and‑dust cycle. The unexpected summer spikes were confined to volcanic fissures on the flanks of Alba Mons, a broad shield volcano in the Tharsis region that, by surface area, rivals Olympus Mons as the planet’s largest volcanic construct.
Further analysis identified fresh, narrow fissures—some extending hundreds of feet—through which the gas was reaching the surface. Hydrogen chloride is a common by‑product of magmatic vents on Earth, where it originates from hot magma beneath the crust. Its appearance on Mars, especially linked to active fissures, provides a “smoking gun” for ongoing, albeit low‑level, volcanic processes.
Implications for Martian Volcanism and Potential Life
Team co‑leader Daniel Mège, a scientist at the Space Research Centre of the Polish Academy of Sciences, said the findings suggest Mars retains enough internal heat to support volcanic activity “until recently, and possibly still does.” The researchers propose that the detected HCl is released from a dormant magma chamber beneath Alba Mons. During the Martian winter, the gas may become trapped by surface ice; when the ice sublimates in summer, the gas is liberated, creating the observed seasonal spikes.
Beyond reshaping the view of Mars as a geologically dead world, the discovery has astrobiological relevance. Volcanic plumbing can generate hydrothermal systems where magma interacts with groundwater, creating warm, chemically rich niches that could have supported microbial life in the planet’s past. Mège highlighted that searching for life in the seeping fissures of Alba Mons would be logical, as such environments could supply both energy and protection from harsh surface conditions.
Scientific Context
Previous orbital imagery had hinted that some Martian volcanoes may have been active within the last few million years, and seismometers have recorded marsquakes, both pointing toward residual tectonic activity. However, direct evidence of recent eruptions or lava flows has been lacking. The TGO’s detection of hydrogen chloride adds a new line of evidence, indicating that volcanic gases are still reaching the surface.
The research, authored by Mège and colleagues, was published in the journal Science Advances on November 4. It underscores a shift from the long‑standing view of Mars as a dead planet toward a model where internal heat and occasional volcanic outgassing continue to shape its environment.
Helene Elliott is the Lead Science & Space Reporter at News Raise. She reports on aerospace missions, astrophysics discoveries, quantum research, and environmental technology.
