Scientists analyzing data from the European Space Agency's ExoMars Trace Gas Orbiter have detected hydrogen chloride gas seeping from fissures near the Alba Mons volcano on Mars, a finding that they say is best explained by ongoing magmatic activity deep inside the planet. The discovery, reported in Science Advances, offers evidence that Mars may remain volcanically active.
The hydrogen chloride molecules were found in trace concentrations of parts per billion during early northern summer, when Mars is near aphelion and the atmosphere is colder and clearer of dust and water vapor. Researchers detected the gas above fissured ground near Alba Mons, the largest volcano on Mars by area, and said the signals were more likely to be magmatic than atmospheric in origin.
Researchers, including co-lead author Daniel Mège of the Space Research Centre of the Polish Academy of Sciences, considered three possible non-atmospheric sources: deep volcanic activity, mud volcanoes that could release HCl if they interact with magma, or decomposition of chlorine compounds on the surface. They said a local igneous source may provide the best explanation.
“The Trace Gas Orbiter was able to find the smoking gun. It was like looking for a needle in a haystack,” Mège said.
The fissures from which the gas appears to escape sometimes form swarms stretching for tens of kilometres and are occasionally ringed by dark halos, perhaps similar to those around fumaroles on Earth, the team reported. If not for something maintaining the fissures, they would have disappeared eons ago under accumulating dust or seasonal landscape changes. The researchers described them as potential chimneys for hydrothermal systems connected to a deep “volcanic plumbing system.”
The detection is the latest in a series of discoveries challenging the view of Mars as a geologically dead world. Mars was very volcanically active during its Hesperian era, 3.7 to 3 billion years ago, and later formed the largest volcanoes in the solar system. Olympus Mons may have shown recent activity around two million years ago.
The implications extend to the search for life. "Looking for Martian life in the seeping fissures of the Alba Mons region would make a lot of sense," Mège concluded. "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."
Analysis
Why This Matters
- The finding suggests Mars still has a warm, magmatic interior, challenging the view of it as a geologically dead world.
- Active volcanism could create hydrothermal systems that provide heat, water and nutrients, making the Alba Mons region a high-priority target for future missions searching for signs of life.
Background
Mars was once thought to be geologically inert, but evidence has accumulated over the past two decades that it remains active. The Trace Gas Orbiter, part of the European ExoMars program, has been mapping the Martian atmosphere since 2016. Its instruments can detect trace gases at parts per billion levels, making it ideal for sniffing out signs of active processes.
What to Watch
- Future observations by ExoMars and other orbiters to see whether the HCl signal recurs or strengthens in subsequent Martian years.
- Robotic or sample-return missions that could target the Alba Mons fissures to search for biological signatures or confirm the presence of active hydrothermal systems.
- Further analysis of Mars's lower atmosphere during aphelion to distinguish magmatic HCl from that produced by atmospheric reactions.
Checked
12 claims in this story checked against 1 source: 12 supported.
Show each claim
- SupportedHydrogen chloride detection on Mars hints at ongoing volcanic activity.ScienceAlert: “the detection of some stinky gas suggests its heart (or gut) is still beating with melty magma.”
- SupportedThe ExoMars orbiter found noxious hydrogen chloride near Alba Mons, researchers say.ScienceAlert: “astronomers using the European Space Agency's (ESA) ExoMars Trace Gas Orbiter (TGO) have reported detecting noxious hydrogen chloride (HCl) wafting around Alba Mons”
- SupportedResearchers detected hydrogen chloride escaping from fissures near Alba Mons.ScienceAlert: “The early summer warming sublimates the overlying ice, allowing the HCl to escape from cracks leading to the Martian interior”
- SupportedThe researchers said ongoing magmatic activity deep inside Mars best explains the finding.ScienceAlert: ““Our results are best explained by ongoing igneous processes in the Martian interior,” the researchers say in the study.”
- SupportedThe discovery was reported in Science Advances.ScienceAlert: “In a new study published in Science Advances”
- SupportedThe discovery offers evidence that Mars may remain volcanically active.ScienceAlert: “Their discovery hints that our neighbor is still magmatically active in its interior.”
- SupportedMège said, “The Trace Gas Orbiter was able to find the smoking gun. It was like looking for a needle in a haystack.”ScienceAlert: ““The Trace Gas Orbiter was able to find the smoking gun. It was like looking for a needle in a haystack,” explains co-lead author Daniel Mège”
- SupportedThe hydrogen chloride was detected in trace concentrations of parts per billion.ScienceAlert: “these stinky signals are thin, with ghost-like concentrations in parts per billion.”
- SupportedThe signals appeared in early northern summer, near aphelion, when the atmosphere is colder and clearer of dust and water vapor.ScienceAlert: “These intriguing signals appear in early summer in the northern hemisphere, when Mars is near aphelion”
- SupportedAlba Mons is the largest volcano on Mars by area.ScienceAlert: “Alba Mons, the largest volcano (by surface area) on Mars.”
- SupportedThe fissures sometimes form swarms tens of kilometres long and are occasionally ringed by dark halos that may resemble those around Earth fumaroles.ScienceAlert: “the HCl is linked to small fissures that sometimes form “swarms” stretching for tens of kilometers, occasionally ringed with dark-colored halos, perhaps similar to those around fumaroles on Earth.”
- SupportedMège said, “Looking for Martian life in the seeping fissures of the Alba Mons region would make a lot of sense,” and that active hydrothermal systems could provide ingredients and energy for microorganisms and shield them from the surface environment.ScienceAlert: ““Looking for Martian life in the seeping fissures of the Alba Mons region would make a lot of sense,” Mège concludes. “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.””
