Mars Volcanoes Show Signs of Dormant Geological Activity

Why did winter gas show up in summer?

The team first noticed spikes of hydrogen chloride during Martian summer in the northern hemisphere, when and where the gas should not appear. It normally peaks there during winter and disappears in summer, a pattern linked to Mars' water and dust cycle. The exception occurred over fissures on the flanks of Alba Mons in early summer.

The researchers' proposed mechanism has three steps:

• Gases rise from Mars' interior during the northern winter.
• Ice blocks the gases at the surface.
• In summer, the ice sublimates—changes directly from a solid into a gas—and releases the trapped gases, producing the spikes.

This sequence fits the timing and location of the detections, but it remains a model rather than a direct view of the subsurface. Mège said the team had to examine all possible chemical processes in the Martian atmosphere. He described the work as rigorous, critical and creative, and the data as complex.

The spatial distribution of the seeping gas made a volcanic origin look obvious to Mège, but the team still had to demonstrate it. He also called the measurement remarkable because TGO caught only a handful of molecules from a perhaps intermittent source while moving continuously along its orbit to monitor the whole Martian atmosphere.

Takeaway: Summer sublimation of ice offers a plausible way to release trapped volcanic gas and explain the seasonal spikes.

Has Mars proved it is still volcanically active?

Scientists have long suspected that Mars was geologically “dead.” Earlier orbital images suggested that some volcanoes had been active within the last few million years, and seismometers had recorded “marsquakes,” or seismic shivers. Those findings implied an active interior, but observers had not seen eruptions or lava flows.

The new study adds a chemical trail and a set of narrow fractures to that older evidence. It supports the possibility of intermittent activity until recently and possibly now. It does not document an eruption, a new lava flow or a direct measurement of molten rock, so “sleeping” is more accurate than either “dead” or “actively erupting.”

Takeaway: The observations support recent or possible intermittent volcanism, but they do not confirm an eruption today.

Why do the fissures matter for the search for life?

Mège and colleagues theorize that the gas travels through “volcanic plumbing,” a network of underground pathways supplied by a dormant magma chamber. If magmatic gases were more abundant in Mars' past, they could have supported a thicker atmosphere and a warmer climate. That could have allowed liquid water to cover much of the planet's surface.

The researchers also propose a route to habitable environments. When lava rose through the crust and met groundwater, it could create warm niches for microbial life. Mège argued that scientists should examine the site:

“Looking for Martian life in the seeping fissures of the Alba Mons region would make a lot of sense. 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.”

A hydrothermal system is an environment where heated groundwater circulates through rock. The study does not confirm that one is active at Alba Mons or that microorganisms live there. It does, however, make the seeping fissures a specific target rather than a vague place on a very large planet.

Takeaway: Alba Mons offers a concrete place to examine for habitable niches, not proof that life exists.

The paper appeared in Science Advances on Wednesday, Nov. 4. The result gives researchers looking for life on Mars a specific place to examine, but it confirms neither an active underground magma system nor living microorganisms.