Electricity from storms seems to regulate chlorine on Mars

Electricity from dust storms may be the main driving force behind a global Martian chlorine cycle, the existence of which was detected by the ExoMars TGO orbiter.

Scientists consider chlorine to be one of the five “mobile” elements on Mars (the others are hydrogen, oxygen, carbon, and sulfur). This means that chlorine, in different forms, goes back and forth between the surface and the atmosphere of Mars. In the ground, chloride deposits—similar to Earth’s shallow saline or salt beaches—are widespread. These chloride deposits probably formed in the early history of Mars as precipitated chloride salts from brines.

In a new study, planetary scientist Allan Wang of Washington University in St. Louis shows that an especially effective way of transporting chlorine from soil to air on Mars is through reactions triggered by electrical discharges generated in Martian dust. The findings are published in Geophysical Research Letters.

Wang and his collaborators carried out a series of experiments in which they obtained high yields of chlorine gas from common chlorides, all by applying electrical discharges to the solid salts under conditions similar to those on Mars. They conducted these experiments using a University of Washington planetary simulation chamber (called the Planetary Environment and Analysis Chamber, or PEACh).

“The high rate of chlorine release from common chlorides revealed by this study indicates a promising pathway for converting surface chlorides into the gas phases we now see in the atmosphere,” Kevin Olsen, a researcher at the Open University, said in a statement. , in the United Kingdom, and co-author of the new study.

These findings support the idea that Martian dust activities may drive a global chlorine cycle.” With the ExoMars TGO (Trace Gas Orbiter) mission, we observed repeated seasonal activity that coincides with global and regional dust storms,” ​​he added. .