Possible signs of modern activity found above Martian volcano Alba

The gas is detected by the Russian ACS instrument aboard the European Trace Gas Orbiter (TGO), and scientists from the Space Research Institute of the Russian Academy of Sciences (IKI RAN) are working with its data. The researchers analyzed 78 observations: overall, the hydrogen chloride content in the Martian atmosphere fluctuates along with dust and water vapor cycles, but above the slopes of Alba, its concentration increases locally at the beginning of each northern summer.

Alba is the largest volcano on Mars by surface area, measuring 1,350 by 1,130 kilometers with an elevation of 6,800 meters. Comparing the zones of increased gas concentration with high-resolution images, the authors found fractures there up to hundreds of meters long and several tens of centimeters wide, with the soil around them having a distinct color. The fractures cut through a layer of ice that is about 630,000 years old. According to the researchers, ice seals them in winter, and in summer it sublimates, allowing gases to escape to the surface.

According to the authors, calculations failed to explain the observations without volcanic processes. There is no talk of an eruption, but the release of gas is considered a sign of a hot magma reservoir beneath the surface. In this case, near permafrost, groundwater could be located relatively shallowly; in the IKI RAN publication, such "warm subterranean oases" are called the most promising direction for searching for Martian life.

At the same time, hydrogen chloride remains indirect evidence: scientists have yet to confirm the volcanic source of the gas and the persistence of activity in the present day.