Mars Gas Near Alba Mons May Point to Volcanic Seepage

Researchers say hydrogen chloride detected above fissures near Mars’s Alba Mons may be escaping from underground volcanic activity, offering a possible sign that the planet’s interior remains active. The finding does not establish that Mars has ongoing volcanism, and the gas’s source has not been confirmed directly. The ExoMars Trace Gas Orbiter recorded hydrogen chloride in the Martian atmosphere, with researchers identifying concentrations above fissures in the Alba Mons region. The study team links the gas to possible magmatic seepage through cracks in the surface. Hydrogen chloride is associated with volcanic emissions on Earth, but that resemblance does not prove a volcanic origin on Mars. Images from the orbiter’s CaSSIS camera showed narrow fissures in the region, some hundreds of metres long, alongside changes in surface colour. Researchers propose that gases could rise through the fissures from a subsurface magma system and leave deposits that account for the discolouration. They also suggest that ice may block the openings during colder periods and that seasonal thawing could allow trapped gas to escape. These are explanations offered by the team, not direct...