Gas seeping from volcanic rifts on Mars suggests the planet may not be geologically dormant but could instead harbor conditions suitable for life, according to a new study by scientists at the Space Research Institute in Moscow.
The researchers propose that life could exist within these fissures, particularly in the Alba Mons region. "If hydrothermal systems are active, they could contain the ingredients and energy needed for microorganisms to develop, and shield microorganisms from the hostile and changing environment above the surface," said Daniel Mege, co-lead author of the study.
Mars possesses the largest volcanoes in the solar system, but their activity level has remained uncertain. While marsquakes have been detected and orbital imagery indicates some volcanic activity within the last few million years, no recent lava flows or eruptions have been observed.
In 2021, the ExoMars Trace Gas Orbiter (TGO) recorded unusual spikes of hydrogen chloride gas in the Martian atmosphere. This gas's concentration varies seasonally, peaking in the northern hemisphere's winter and diminishing in the summer, a pattern often linked to Mars' dust and water cycles. However, on Earth, hydrogen chloride is frequently associated with magmatic vents, prompting the scientists to investigate a similar phenomenon on Mars.
Using the TGO's CaSSIS camera, the team observed fresh, narrow fissures on Alba Mons, some measuring hundreds of meters long. "The Trace Gas Orbiter was able to find the smoking gun," Professor Mege stated, emphasizing the difficulty of detecting such a subtle signal. "It's truly amazing that it spotted a handful of molecules from a perhaps intermittent source, whilst moving continuously along its orbit to monitor the whole martian atmosphere."
The seasonal variation in hydrogen chloride levels is hypothesized to be due to ice blocking the fissures in winter, with the gas being released as the ice melts in early summer. The study suggests that higher levels of hydrogen chloride in Mars' past could have contributed to a thicker atmosphere and a warmer climate, potentially allowing liquid water to exist and creating habitable environments.
Colin Wilson, ESA's project scientist for the ExoMars Trace Gas Orbiter, commented, "These findings may prove to be TGO's greatest success yet."