Hydrogen chloride has been detected for the first time on planet Mars, discovered by the ExoMars Trace Gas Orbiter satellite co-operated by the European (ESA) and Russian (Roscosmos) space agencies.
The satellite has been collecting atmospheric data on Mars since the spring of 2018, searching for methane but also new gases, the Royal Belgian Institute for Space Aeronomy said in a press release.
Now the latest research of the Red Planet has led to the discovery of hydrogen chloride, a halogen gas. It’s the first time that the gas has been detected there and “represents a new chemical cycle to understand.”
How did this gas, composed of a hydrogen atom and a chlorine atom, end up in the Martian atmosphere?
It comes from salts in the form of sodium chloride, remnants of ancient oceans evaporated and trapped on the dusty surface of Mars, the Aeronomy Institute explains. These salts are then lifted into the atmosphere with the winds.
“Sunlight warms the atmosphere, causing dust to rise, as well as water vapour (H2O) released by ice caps. Salt dust reacts with atmospheric water to release chlorine, which itself reacts with molecules containing hydrogen to create hydrogen chloride.”
To release chlorine, water vapour is needed. Hydrogen is also needed to form this gas. Martian dust also plays its part, with more hydrogen chloride (HCI) observed as dust activity increases.
“In-depth laboratory tests and new global atmospheric simulations will be necessary to better understand” the phenomenon behind the presence of chlorine. Continuous observations should also confirm that “the rise and fall of HCl is due to summer in the southern hemisphere.”