Gas Seeping From Mars Fissures Suggests Its Volcanoes Are Dormant, Not Dead

Mars may not be the geologically dead world many scientists have assumed. A spacecraft orbiting the planet has detected a volcanic gas leaking to the surface through fresh cracks in the Alba Mons region, according to Space.com, which suggests the planet's volcanoes could be dormant rather than extinct.

The findings were published Wednesday, Nov. 4, in the journal Science Advances. They come from the ExoMars Trace Gas Orbiter (TGO), a mission of the European Space Agency.

What the orbiter found at Alba Mons

TGO detected gas containing hydrogen chloride rising through volcanic fissures in Alba Mons, Space.com reported. On Earth, the same compound commonly escapes from magmatic vents, where it comes from hot magma below the surface. The researchers read its presence on Mars as a sign of dormant volcanism.

Alba Mons sits in the Tharsis region, which also holds Olympus Mons. Olympus Mons is the tallest volcano in the solar system, at around 16 miles (26 kilometers) above the surrounding plains. Alba Mons is the largest volcano by surface area. Space.com framed the result as a hint that Olympus Mons could be a "slumbering giant," though the new measurements concern Alba Mons.

How the team spotted something odd

The researchers first noticed spikes of hydrogen chloride in the northern hemisphere during Martian summer, a time and place where the gas should not appear. Normally it peaks in the northern hemisphere in winter and fades in summer, a pattern tied to the planet's water and dust cycle. The exception was over volcanic fissures on the flanks of Alba Mons in early summer.

TGO then found fresh, narrow fissures in the region, in some cases hundreds of feet long, which the report describes as a clear sign of volcanism. The team thinks gas rises from the interior through the winter and gets blocked by ice. When that ice turns directly from solid to gas in summer, the trapped hydrogen chloride is released and shows up as a spike.

Daniel Mège, a team co-leader at the Space Research Centre of the Polish Academy of Sciences, said in a statement to Space.com that a large part of the work was ruling out other chemical processes in the Martian atmosphere that might explain the gas. "The TGO was able to find the smoking gun," he said.

Why the result stands out

Earlier clues pointed in the same direction. Orbital images had shown that some volcanoes appear to have been active within the last few million years, and seismometers have picked up "marsquakes." Yet actual eruptions and lava flows have not been seen.

Mège said the findings suggest Mars kept enough internal heat to support volcanic activity until recently, and possibly still does. The team proposes that the gas is linked to a dormant magma chamber below the surface. That is the researchers' interpretation; no eruption has been observed.

What this means for the search for life on Mars

The result does not show life exists on Mars, but it could shape where scientists look. According to Space.com, magmatic gases such as hydrogen chloride would have been more abundant in the past, helping create a thicker atmosphere and a warmer climate. That could have allowed liquid water to cover much of the surface. Where lava met groundwater, warm niches suited to microbes could have formed.

Mège said searching for Martian life in the seeping fissures of Alba Mons would make sense. If hydrothermal systems there are active, he said, they could hold the ingredients and energy microorganisms need, and shelter them from the harsh, changing conditions at the surface.

For readers, the main takeaway is a shift in how Mars may be understood: not a frozen relic, but possibly a planet with a still-warm interior. This is a single study based on orbital measurements, and the dormant magma chamber remains a theory rather than a direct observation.

Around Prague, based on reporting by Space.com