Chlorine on the Surface, Chlorine in the Air, What Is the New Global View of the Martian Chlorine Cycle?

Journal article : Comment

Plain Language Summary: Hydrogen chloride is a gas emitted by volcanoes on Earth. It has been hunted on Mars as a sign of recent volcanic activity, and was found with the ExoMars Trace Gas Orbiter (TGO), whose main objective is to find rare gases in the Martian atmosphere that tell us about biological or geological activity there. This commentary examines the recent results presented by Faggi et al. (2025), https://doi.org/10.1029/2025je009105 on a campaign to measure HCl in the Martian atmosphere from the Earth. From a telescope on Earth, the measurements cover the whole surface of Mars revealing how HCl is distributed and how that changes over a year. Here, we discuss the context of these results and their implications for chlorine deposits seen on the surface.

Authors: Olsen, KS

• Publication status: Published
• Publisher: American Geophysical Union
• Journal: Journal of Geophysical Research: Planets
• Volume: 131
• Issue: 1
• Article number: e2025JE009603
• Publication date: 2025-12-26
• Acceptance date: 2025-12-14
• DOI: 10.1029/2025je009603
• EISSN: 2169-9100
• ISSN: 2169-9097
• Language: English
• Subtype: Comment