How’s the Weather on Mars? Electrically Charged Dust Storms Drive Martian Chlorine Cycle

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How’s the weather condition on Mars? Tough on rovers, however excellent for producing and moving extremely reactive chlorine substances. New research study from Washington University in St. Louis planetary researchers reveals that Martian dust storms, like the one that ultimately closed down the Opportunity rover, drive the cycle of chlorine from surface area to environment and might clarify the capacity for discovering life on Mars.

Recent research study from Alian Wang, research study teacher in the Department of Earth and Planetary Sciences in Arts & Sciences, and partners at WashU, Stony Brook University, Shandong University and NASA’s Goddard Space Flight Center constructs on a previous evaluation of Martian dust storms as a necessary consider the chemical advancement of the red world’s surface area. Their newest paper shifts focus to the electrochemical procedures arising from dust storms that might power the motion of chlorine, which is continuous on Mars today. The research study was released May 28 in the Journal of Geophysical Research: Planets.

While earlier research studies have actually developed the reasonably high concentration of chlorine on Mars and recommended volcanic and hydrological activity as historic motorists of the chlorine cycle, Wang has actually experimentally demonstrated how electrostatic discharge (ESD) created by dust storms might play a crucial function in Mars’ surface area and climatic chemistry now.

Given the relative abundance of chlorine at Mars’ surface area, Wang and her partners set out to check out the development of this contemporary chlorine cycle on Mars: How thrilled chlorine atoms get launched to the environment, then re-deposited on the surface area and partly percolated into the subsurface. They likewise studied what ramifications that chlorine cycle may have for discovering traces of life on Mars.

Martian Dust Storm

Martian dust storm. Credit: NASA

“In the past, when conditions were different, and there was perhaps more water on Mars, there would have been a difference in the surface chemistry and in the behavior of chlorine,” stated Bradley Jolliff, a co-author on the paper and the Scott Rudolph Professor of Earth and Planetary Sciences. “We don’t fully understand how Mars got to the present state of chlorine enrichment at the surface, but we’re very interested in knowing, as we drill down into the subsurface, how highly oxidized compounds of chlorine, called chlorates and perchlorates, interact with other elements. It’s been kind of a puzzle.”

In an unique center called the Planetary Environment and Analysis Chamber (PEACh), Wang duplicated the conditions of electrostatic discharge that can be caused by Martian dust storms to establish a deep understanding of surface-atmosphere chemical interaction.

Her outcomes were considerable. Not just are the chlorine substances seen on the Martian surface area oxidized by electrostatic discharge throughout dust storms, however those dust storms likewise are producing lots of totally free radicals from Martian climatic particles. That triggered the thrilled chlorine particles to be launched, recombined and after that moved in between the surface area and the environment of Mars, establishing an active and continuous chlorine cycle.

“This isn’t like what we see on Earth,” Wang stated. “Photochemical reactions, driven by the sun, occur on both planets, but on Mars we have these global dust storms once per two Martian years, regional dust storms each year and countless dust devils everywhere.”

In the past, Mars may have been warmer and wetter, however the cold, dry environment it has today makes electrostatic discharge an effective aspect. “Electrochemistry may be the bigger player on the surface of Mars right now,” Wang included.

These results line up with other analyses of Martian surface area chemistry, and the conditions they indicate do not bode well for discovering biomarkers at the surface area. However, Wang kept in mind that comprehending the surface area chemistry is our finest possibility at understanding what life on Mars may have appeared like.

As the mission to discover indications of life on Mars continues, this line of research study will establish even more. Wang expects future partnerships with biogeochemists to broaden the look for biomarkers into the Martian subsurface.

“Because the geochemistry at the surface could go into the subsurface, it will affect how the trace of life on Mars could be detected,” Wang stated.

Jolliff included, “We’ve seen from the Spirit rover, when it was dragging one of its wheels through the soil, that what was in the immediate subsurface was different from what was right at the surface — very much a surface oxidation phenomenon. So understanding that surface chemistry becomes very important and drives us to the conclusion that if we want to really test for extant or past life, we’ve got to get below the surface.”

Reference: “Chlorine Release From Common Chlorides by MartianDust Activity” by Alian Wang, Yuanchao Yan, Bradley L. Jolliff, Scott M. McLennan, Kun Wang, Erbin Shi and William M. Farrell, 28 May 2020, Journal of Geophysical Research: Planets.
DOI: 10.1029/2019JE006283

Funding for this research study was offered by NASA. The work was likewise supported by Washington University’s Institute of Materials Science & Engineering  and McDonnell Center for the Space Sciences.

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