An atmospheric research spacecraft currently in orbit around Mars has uncovered the distinctive gas hydrogen chloride above surface cracks on a colossal ancient volcano, indicating that the Red Planet may still exhibit volcanic activity.
This discovery could have significant implications regarding the possibility of subsurface environments on Mars that are suitable for microbial life. Researchers noted that the ExoMars Trace Gas Orbiter has observed this gas, commonly found in volcanic emissions on Earth, within the lower atmosphere of the Alba Mons region.
Alba Mons, the largest volcano on Mars in terms of surface area, is a broad, gently sloping structure known as a shield volcano, resembling the shape of a warrior’s shield. It is situated in the northern hemisphere of the planet.
“Our analysis suggests that volcanic seepage is the most probable source of the hydrogen chloride,” explained Daniel Mège, a planetary scientist from the Space Research Centre of the Polish Academy of Sciences and co-lead author of the research published in the journal Science Advances.
The seepage of hydrogen chloride may be attributed to volcanic outgassing from the numerous surface fissures in the Alba Mons area, potentially linked to an underground magma chamber.
This image shows a crater and linear fractures on the eastern flank of Alba Mons. (NASA/JPL-Caltech/ASU)
“The gas is released from chlorine-containing compounds that are dissolved in magma as it ascends and the pressure decreases. Therefore, its presence aligns with expectations of magmatic degassing,” added Alexander Trokhimovskiy, a planetary scientist and co-lead author from the Space Research Institute of the Russian Academy of Sciences.
This finding suggests that Mars is not geologically inactive but is instead in a phase of relative dormancy.
“This implies that the interior of Mars may still hold enough heat to facilitate magmatic processes, and that trace gases in the atmosphere can offer a means to detect and study geological activity that is otherwise challenging to observe directly,” Trokhimovskiy stated.
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Bodies within our solar system that are confirmed to be volcanically active are quite rare, including Earth, Venus, and Jupiter’s moon Io.
The surface of Mars has been significantly shaped by ancient volcanic activity, with the planet boasting Olympus Mons, the tallest volcano in the solar system. However, the question of whether Mars exhibits ongoing volcanic activity has remained ambiguous.
Olympus Mon, photographed by Viking 1 in 1978. It’s the largest volcano and highest mountain in our solar system. (NASA/Jet Propulsion Laboratory)
“While there have been reports of volcanic activity on Mars from a few million years ago, no evidence of current magmatic activity has been documented,” Mège noted.
Additionally, Marsquakes recorded by NASA’s InSight seismometer have indicated potential volcanic activity.
On Earth, sulfur dioxide is generally found in higher concentrations than hydrogen chloride in volcanic emissions. However, due to the differing compositions of the two planets, hydrogen chloride might be more prevalent on Mars.
“It has a strong odor, and I would advise against inhaling it as it is corrosive and can cause irritation or burns to nasal tissues,” Mège warned.
NASA scientists believe there could be an ocean of water deep below the surface of Mars. It’s a discovery that advances the search for life beyond our planet and suggests Mars might have conditions that could sustain microbial life, either in the past or present. Matthew Cimone, head interpreter at the H.R. MacMillan Space Centre in Vancouver, tells us more about this finding.
The orbiter, a joint project between the European Space Agency and the Russian space agency Roscosmos, was the first to identify hydrogen chloride in Mars’ atmosphere and has recorded yearly increases in this gas along the northern side of Alba Mons during early summer.
The researchers believe that the fissures may be obstructed by ice at other times of the year, but thawing due to rising temperatures in early summer allows volcanic gases trapped beneath the surface to escape into the atmosphere.
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The presence of subsurface magma has intriguing implications regarding whether Mars currently supports any forms of life. Active volcanic processes could mean that heat pockets might persist within the planet’s crust, its outermost layer.
It is already established that Mars contains water trapped beneath its surface, and life on Earth is believed to have first emerged billions of years ago in hydrothermal environments.
“As magma rises through the crust, it can interact with and heat underground water, creating environments that are shielded from the harsh conditions on the surface,” Trokhimovskiy explained.
“These active hydrothermal systems could offer the energy sources and favorable conditions necessary to support microbial life, making warm subsurface environments some of the most promising areas in the search for life on Mars.”