Mars may not be geologically dead but merely "asleep" - that is the conclusion the authors of a study published in the journal Science Advances are leaning toward. An international team led by Alexander Trokhimovsky linked emissions of hydrogen chloride in the planet's atmosphere to a possible rise of gases from the interior through fresh fissures in the area of Alba volcano.
Hydrogen chloride - a gas that on Earth is common at volcanic vents - was first detected in the Martian atmosphere by the ExoMars Trace Gas Orbiter (TGO) in 2021. New data showed that the gas concentration varies by season, reaching a maximum in northern winter and almost disappearing in summer. The exception was bursts in early summer over volcanic faults on the slopes of Alba - always in the same place and at the same time.
The CaSSIS camera on TGO then observed narrow fresh fissures in this area, some hundreds of meters long, with a change in surface color around them. Scientists suggest that in winter, at temperatures down to minus 120 degrees, the fissures are blocked by ice, and in early summer, when the ice evaporates (sublimates, that is, passes from a solid state directly into gas), they become channels for chlorides to escape. Similar processes occur at terrestrial fumaroles - openings through which volcanic gases escape.
"Our results indicate that Mars has retained enough internal heat for volcanic activity until recently, and possibly still does," Daniel Mege, a professor at the Space Research Center of the Polish Academy of Sciences and a co-author of the work, was quoted as saying by the European Space Agency's press service.
Mars has the largest volcanoes in the solar system, but how active they are is unknown. Orbital images show that some of them may have erupted in the last few million years, and seismometers have recorded marsquakes. However, no one has observed new lava flows or eruptions. The authors emphasize that they are talking about signs of a dormant magma chamber, not an active volcano.
The researchers do not rule out that in the past such gases made the atmosphere denser and the climate warmer, allowing liquid water to cover a significant part of the surface. If rising magma met groundwater, warm habitable niches could have arisen. "Searching for Martian life in the Alba fissures would make a lot of sense," Mege believes.
The work is based on a joint analysis of atmospheric and geological data. The limitation is that the conclusions rest on observations of gases and fissures, not on direct evidence of eruptions. A direct link between the emissions and magma remains the most likely explanation, but not a proven fact.