Mars Orbiter Spots Possible Volcanic Gas Leaks Near Giant Alba Mons

A spacecraft orbiting Mars has picked up a possible signal of hydrogen chloride gas leaking from rifts near Alba Mons, the largest volcano on the planet by surface area. The researchers read it as a sign of hot magma beneath the surface, according to Live Science. The team also suggests the area could host an environment similar to the hydrothermal vents on Earth where life likely began.

The study was published Wednesday (Nov. 4) in the journal Science Advances. The authors stress that more research is needed to confirm the emissions, and the link to volcanic activity remains a hypothesis.

What did the spacecraft detect?

Europe's ExoMars Trace Gas Orbiter first detected hydrogen chloride in the Martian atmosphere in 2021, Live Science reported. Scientists were cautious about tying it to volcanoes. The gas seemed to follow the seasons, it was not concentrated over a likely volcanic region, and other volcanic gases such as sulfur were absent, co-author Kevin Olson of the University of Oxford told the outlet.

Later work changed the picture. The gas also showed up in the northern hemisphere's winter, and not only in the southern spring and summer. Olson said the out-of-season measurements were close together in place and time in two consecutive Mars years, which he called surprising.

How did the team test the idea?

The researchers ran a targeted campaign of measurements at that time and place. It lasted two Mars years, which is roughly four Earth years, because a Mars year is closer to two Earth years. The team confirmed a “distinct and pronounced signal” that then faded below the spacecraft's detection threshold.

Olson said that pattern looks more like a puff of gas entering the atmosphere than ordinary atmospheric chemistry. Across four Mars years of observations, he said, the gas has appeared locally and nowhere else.

Is this the first sign of magma on Mars?

No. According to Live Science, NASA's InSight lander interpreted the presence of magma earlier this year from seismic observations and modeling. First author Alexander Trokhimovskiy, of Russia's Space Research Institute, told the outlet the new findings are the strongest evidence yet of gases released by dormant Martian volcanoes. He described the work as a complementary and potentially independent line of evidence.

Co-author Daniel Mège, a planetary geologist at the Polish Academy of Sciences, identified the fissures where the gas may be escaping. He said the two data sets strengthen each other: InSight spotted activity in the crust, while the orbiter detected emissions in the atmosphere.

Why does it matter?

For readers following the search for life beyond Earth, the finding points to a place where heat, chemistry and possibly water-related processes could overlap. Mège noted that magma activity is not in itself a sign of life. He added that Earth's first life-forms came from hydrothermal zones, which combine materials and energy in a similar way to the possible Martian vents.

He was careful about the limits. Conditions in the area would need to stay favorable for at least millions of years for life to form. If those requirements are met at the local scale of the seepage structures, he said, “living organisms might wait for us to discover them.” But keeping conditions stable that long in such a small area, he cautioned, is not obvious.

Nothing in the study shows that life exists on Mars. The result is a possible signal of gas release that needs confirmation, and it suggests where future observations might look.

Around Prague, based on reporting by Live Science