Mars’ volcanoes may not be entirely inactive. Research based on data from the European Space Agency’s ExoMars Trace Gas Orbiter (TGO) reports hydrogen chloride in the atmosphere above Alba Mons, alongside narrow cracks in the ground that could be vents for volcanic gases.

The study, led by Alexander Trokhimovskiy and published in Science Advances, examined 78 observations of the region. The gas generally changes with the seasons and Mars’ dust and water cycles, but researchers found repeated increases above the same area on Alba Mons during early northern summers. The detected concentrations were small, and the team said it was notable that the orbiter captured gas that may emerge only intermittently.

Images from the CaSSIS and NASA’s HiRISE cameras showed cracks beneath the area where the gas appeared. Some are only inches to a few feet wide, while clusters extend for miles along ridges. They cut through an icy surface layer formed about 630,000 years ago, indicating that the cracks developed more recently in geological terms.

The researchers suggest that gases may escape through the fissures, which could be sealed by ice during the cold Martian winter and open as the ice turns directly into vapor in summer. Hydrogen chloride can persist after an eruption even when sulfur dioxide is scarce, the team noted, making the absence of sulfur dioxide insufficient to rule out volcanic activity.

Earlier clues have included marsquakes recorded by NASA’s InSight lander and relatively young lava flows and ash deposits in volcanic regions. However, searches for heat or visible surface changes have not provided a clear sign of present-day activity. The new observations therefore point to a possibility rather than confirming that magma is currently moving beneath Alba Mons.

If volcanic gases are escaping, the cracks could also be places to investigate for underground environments where liquid rock interacts with water. Co-lead author Daniel Mège said such hydrothermal systems, if active, could provide ingredients and energy that microorganisms need, while offering protection from the harsh conditions at the surface.

Sources: Mashable.