New findings from a European Space Agency spacecraft suggest that Mars may still have volcanic activity beneath its surface. This raises questions about whether conditions suitable for microbial life could exist underground.

An international research team has identified unusual concentrations of hydrogen chloride gas above narrow fissures near Alba Mons, one of the planet's largest volcanoes. Scientists believe the gas could be escaping from hot magma deep beneath the Martian crust, offering some of the strongest atmospheric evidence yet that the planet's interior may remain geologically active.

The discovery, reported Nov. 4, 2026, in the journal Science Advances, could change how researchers understand the Red Planet's geological history and where future missions should search for evidence of life.

Although Mars has long been considered largely dormant, scientists have accumulated evidence suggesting that volcanic processes may have continued much more recently than previously believed. The latest findings add an important new clue: gases potentially rising from underground volcanic systems.

Researchers caution that the observations do not establish that an eruption is imminent or that life exists on Mars. However, they suggest that underground environments heated by volcanic activity could provide conditions favorable to microorganisms.

Hydrogen Chloride Provides a Critical Clue

The investigation centers on hydrogen chloride, a chemical compound made of hydrogen and chlorine, commonly represented as HCl.

On Earth, hydrogen chloride can escape through volcanic vents as magma rises toward the surface and releases dissolved gases. Its presence in the Martian atmosphere therefore attracted scientific attention.

The European Space Agency's ExoMars Trace Gas Orbiter first detected hydrogen chloride in the Martian atmosphere in 2021. At the time, scientists were investigating whether the gas originated from geological processes or chemical reactions involving dust, water vapor and salts on the planet's surface.

The earlier observations revealed that hydrogen chloride could be produced through atmospheric chemistry. Winds lift salty dust containing sodium chloride into the atmosphere, where sunlight, water vapor and chemical reactions can help release chlorine compounds.

That discovery initially made it difficult to determine whether the gas had a volcanic origin.

The new research takes the investigation further by identifying a particularly unusual pattern: hydrogen chloride concentrations appearing above the same volcanic region during a specific period of the Martian year.

According to the research team, the localized and recurring nature of the gas emissions makes underground volcanic activity a compelling explanation.

How Scientists Discovered the Possible Volcanic Activity

The breakthrough began when researchers examined atmospheric measurements collected by the ExoMars Trace Gas Orbiter.

Scientists noticed hydrogen chloride spikes during early summer in Mars' northern hemisphere. The timing was unusual because the gas generally follows seasonal patterns associated with dust and water cycles.

Under typical conditions, hydrogen chloride concentrations increase during the northern hemisphere's winter and largely disappear during summer.

However, the researchers identified an exception.

The unusual concentrations repeatedly appeared during early summer above fissures on the northern flanks of Alba Mons.

The team then investigated whether the atmospheric readings corresponded with physical features on the planet's surface.

Using images from the Trace Gas Orbiter's Color and Stereo Surface Imaging System, known as CaSSIS, researchers identified narrow fissures extending hundreds of meters across the volcanic landscape. Some were less than a meter wide.

The team also observed changes in surface coloration surrounding the openings, potentially indicating deposits left behind by escaping gases.

The relationship between the atmospheric measurements and the geological features strengthened the possibility that the hydrogen chloride was coming from beneath the Martian surface.

Study co-leader Daniel Mège of the Space Research Centre of the Polish Academy of Sciences described the discovery as an important breakthrough.

"The Trace Gas Orbiter was able to find the smoking gun," Mège said. "It was like looking for a needle in a haystack."

The spacecraft detected extremely small quantities of gas while continuously monitoring the Martian atmosphere from orbit.

Why the Martian Seasons Matter

One of the most interesting aspects of the discovery involves the way seasonal changes may control when underground gases reach the atmosphere.

During winter, temperatures on Mars can fall to approximately minus 120 degrees Celsius in particularly cold regions. Ice can accumulate over cracks and fissures, potentially blocking gases from escaping.

As temperatures rise during the northern hemisphere's early summer, the ice begins to sublimate.

Sublimation occurs when a solid changes directly into a gas without first becoming liquid.

The melting-free transition allows previously trapped gases to escape through openings in the ground and enter the atmosphere.

Researchers believe this process could explain why hydrogen chloride concentrations increase above the Alba Mons fissures during a particular season.

The proposed mechanism also helps explain why the gas appears to originate from a specific geographical location rather than being distributed uniformly across the planet.

Scientists examined alternative chemical explanations before connecting the observations to possible volcanic activity.

The research team's conclusion is that underground magmatic processes provide a plausible explanation for the unusual combination of atmospheric gas measurements, seasonal timing and geological features.

Alba Mons: A Major Volcanic Region on Mars

Alba Mons is located in the Tharsis volcanic region of Mars, an area known for its enormous volcanic structures.

The region is also home to Olympus Mons, the tallest known volcano in the solar system.

Alba Mons is particularly notable for its enormous surface area and extensive volcanic deposits. Orbital observations have identified lava flows that appear geologically young, suggesting that the region experienced volcanic activity relatively recently in the planet's history.

The newly identified fissures could provide additional evidence that volcanic processes have not completely stopped.

Researchers believe the openings may connect to underground structures associated with magma rising through the Martian crust.

The suspected system could include a dormant magma chamber, where molten rock and volcanic gases remain beneath the surface.

Mège said the findings suggest Mars has retained enough internal heat to support volcanic activity until recently and possibly still does.

If confirmed, the discovery would challenge the assumption that Mars has become entirely inactive beneath its surface.

What the Discovery Means for the Search for Life

The possibility of underground volcanic activity has implications beyond understanding Mars' geological history.

Scientists have long considered water, chemical ingredients and an energy source essential components of potentially habitable environments.

Volcanic systems can provide all three under the right conditions.

If rising magma encounters underground water or ice, it could generate hydrothermal environments containing warm water and dissolved minerals.

On Earth, hydrothermal systems support diverse microbial communities, including organisms living in environments far removed from sunlight.

Researchers believe similar environments could potentially exist beneath the Martian surface.

Such locations could offer protection from the planet's harsh conditions, including intense radiation, extreme temperature changes and a thin atmosphere.

Mège suggested that the Alba Mons fissures could become promising targets for future investigations.

"If hydrothermal systems are active, they could contain the ingredients and energy needed for microorganisms to develop, and shield microorganisms from the hostile and changing environment above the surface," he said.

However, no microorganisms or other direct evidence of life have been identified in the fissures.

The research instead points to a possible environment where microbial life could theoretically survive if water and other necessary conditions are present.

Could Volcanic Activity Have Made Ancient Mars More Habitable?

The discovery could also provide clues about the planet's ancient climate.

Scientists believe volcanic activity may have played an important role in shaping the early Martian environment.

Volcanic gases released into the atmosphere could have contributed to a thicker atmosphere and warmer temperatures, potentially allowing liquid water to exist on the surface for extended periods.

Mars once had rivers, lakes and other features indicating that liquid water was present across parts of the planet.

As the atmosphere changed and the planet cooled, much of its surface water disappeared or became trapped as ice and underground reservoirs.

Researchers suggest that volcanic activity could have helped maintain habitable conditions in the distant past.

If magma-driven hydrothermal systems remain active today, they could provide smaller, localized environments where liquid water and microbial life might still be possible.

These possibilities make volcanic regions particularly interesting for future Mars exploration.

ExoMars Trace Gas Orbiter's Role in the Discovery

The ExoMars Trace Gas Orbiter is a joint European-Russian mission designed to investigate the Martian atmosphere and search for gases that could reveal biological or geological activity.

Its Atmospheric Chemistry Suite uses infrared spectroscopy to identify chemical compounds by measuring how they absorb sunlight at different wavelengths.

When sunlight passes through the Martian atmosphere, different gases leave distinctive absorption patterns. Researchers analyze those patterns to determine which compounds are present and how their concentrations change.

The spacecraft also carries the CaSSIS camera, which provides detailed images of the planet's surface.

Combining atmospheric measurements with high-resolution orbital imagery allowed researchers to connect the unusual hydrogen chloride readings with specific geological structures.

The discovery demonstrates the value of using different scientific instruments together rather than relying on atmospheric or surface observations alone.

Colin Wilson, the European Space Agency's ExoMars project scientist, described the findings as potentially one of the mission's greatest successes.

"These findings may prove to be TGO's greatest success yet," Wilson said.

The most important distinction is that scientists have found evidence consistent with volcanic gas seepage, not proof of a current eruption or extraterrestrial life. This distinction is  more scientifically credible.

Scientists Still Need More Evidence

Despite the excitement surrounding the discovery, researchers emphasize that important questions remain unanswered.

The presence of hydrogen chloride does not independently prove that molten magma is currently moving beneath Alba Mons.

Alternative chemical processes could potentially contribute to the gas emissions, and additional observations will be needed to determine the precise source.

Scientists also have not observed a new eruption or fresh lava flow associated with the suspected activity.

The findings instead provide evidence consistent with underground magmatic processes and possible volcanic outgassing.

Future spacecraft observations and investigations of the Martian surface could help determine whether the fissures connect to active hydrothermal systems or underground magma chambers.

For scientists searching for extraterrestrial life, the discovery offers a potentially important new direction.

Mars may appear cold and inactive at the surface, but its interior could still retain enough energy to support geological processes and possibly habitable underground environments.

The question now is whether those hidden environments contain the water, chemistry and energy needed to sustain microbial life.