New insights into Martian chlorine fluctuations linked to dust storms
The atmosphere of Mars shows elevated chlorine levels when electrical discharges occur during dust storms, a finding reported by researchers at the University of Washington.
During the Euro-Russia orbital mission ExoMars TGO, scientists repeatedly observed variations in atmospheric chlorine on Mars. The cause remained unclear, and satellite instruments lacked the ability to pinpoint the gas’s source.
A team of American scientists explored a leading hypothesis: that the rise in atmospheric chlorine is tied to dust storm activity. These storms can loft large particles of rock, and friction between them can generate lightning. The dust itself contains minerals such as carbonates, chlorides, and other soluble salts.
To test this idea, researchers created a sealed simulation of the Martian atmosphere. They added Martian soil salts to the chamber and simulated electrical discharges. Under these controlled conditions, the analogue soil released chlorine. In a typical moderate artificial dust storm lasting several hours, the electrical discharges liberated approximately 0.1 to 1 percent of the chlorine atoms present in the suspended soil material.
Experts stated that this amount is sufficient to account for the observed chlorine increases during the intense dust storms recorded in 2018 and 2019.
The study underscores how electrical activity within Martian dust storms may contribute to seasonal and episodic chemical changes in the planet’s near-surface atmosphere.