Mars Volcano Alba Mons Leaks Hydrogen Chloride Gas
Active volcanic processes may still shape the surface of Mars, according to new data from the European-Russian ExoMars mission analyzed in research published in Science Advances. Scientists detected hydrogen chloride gas leaking from the subsurface near Alba Mons, an ancient volcano in the northern hemisphere.
The ExoMars satellite first identified hydrogen chloride gas in the Martian atmosphere a decade ago during southern hemisphere summer dust storms. At the time, researchers attributed the gas to reactions between water vapor and salt from lofted surface material. However, in 2020, the satellite detected the same gas in the northern hemisphere during the northern summer—an anomaly that repeated annually.
Alba Mons is a vast volcanic structure that went extinct millions of years ago, but the research team concluded that underground magmatic activity provides the most likely explanation for the recurring gas. On Earth, hydrogen chloride gas forms within underground magma reservoirs. The findings suggest Mars still harbors active, albeit dormant, volcanoes more than five years after the initial anomaly prompted a closer look.
Seasonal Ice Traps Subsurface Gas Until Summer
Volcanoes typically release gases regardless of seasonal shifts, but the Mars measurements only appeared during the northern summer. Researchers proposed that subsurface ice blocks escape routes through ground fractures during the winter months. When summer temperatures thaw the ice, the trapped gas leaks into the atmosphere.
Satellite images from the ExoMars mission revealed fractures measuring up to one hundred meters long and several meters wide near the volcano. Colin Wilson of the European Space Agency noted that patches of lighter-colored soil along these fractures suggest local outgassing occurs there, comparable to fumaroles near Naples.
Planetary geologist Sam Poppe of the Polish Academie of Sciences, who was not involved in the study, pointed to supporting evidence from other missions. Recent findings elsewhere on Mars identified solidified lava estimated to be less than one million years old, while the InSight lander recorded seismic quakes typical of underground magma movement. Poppe described the direct detection of hydrogen chloride gas as a smoking gun for ongoing volcanic activity.
Mars may not be geologically dead after all. 🔴 Our ExoMars Trace Gas Orbiter has detected hydrogen chloride above volcanic fissures in the Alba Mons region, which scientists suggest could be linked to dormant volcanic activity beneath the surface. Read more:… pic.twitter.com/7D4B8MggQi
Frequently Asked Questions About Martian Volcanism
* How did researchers rule out dust storms as the source of the northern gas?
Southern dust storms produce hydrogen chloride only during the southern summer, whereas the ExoMars satellite tracked the recurring anomaly specifically during the northern summer in the vicinity of Alba Mons.
* What evidence besides gas leakage points to active magma on Mars?
The InSight lander detected seismic activity consistent with underground magmatic movement, and researchers previously located patches of solidified lava estimated to be less than one million years old.
* Could future missions witness an actual volcanic eruption on Mars?
Researchers consider the necessary components, including moving magma and underground outgassing, to be present. However, because the surface has remained largely unchanged for hundreds of thousands of years, an immediate eruption remains unlikely.
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