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Martian landslides could help explain the mysterious lines seen on the surface of the Red Planet, according to a new study.
For years, scientists analyzing the Martian surface have detected clusters of dark, narrow lines that appear seasonally on steep slopes exposed to the sun in warmer regions. Previous research has suggested that these enigmatic dark streaks, called recurring slope lines (RSL), are signs that salt water regularly flows over the Red Planet during its hottest seasons.
Recent missions to Mars have revealed that the planet has huge undergrounds ice packs. Previous work suggested that warmer temperatures during the Martian spring and summer could help generate salty brines capable, at least for a time, of remaining liquid in the cold, thin air of the Red Planet.
Related: The search for water on Mars in pictures
However, geologists have discovered problems with the concept of brine causing RSL, explained lead study author Janice Bishop, a planet specialist at the Search for Extraterrestrial Intelligence (SETI) Institute and the NASA Ames Research Center, both. located in California’s Silicon Valley. For example, the angle of slopes where RSL occurs and the characteristics surrounding their starting point “are largely incompatible with a liquid flow process,” she told Space.com.
Now Bishop and his colleagues suggest that chemical reactions could make the Martian surface vulnerable to landslides that could explain RSL.
“Although the surface of Mars today is dry and hard and cold and dominated by wind and abrasion, below the surface, micro-scale interactions of salts with tiny particles of ice and liquid water can still happening today, ”Bishop said.
Scientists focused on the chemical reactions between sulfated minerals such as gypsum with chloride salts, of which table salt is a variety. “On Earth, interactions between gypsum and chloride salts have caused parts of caves to collapse, sinkholes in soft sediments near lakes and salt ponds, and roads to heave,” Bishop said.
The researchers hypothesized that similar interactions could occur on Mars, although cold, dry conditions would slow these reactions. “I am very excited about the prospect of active chemistry beneath the surface of Mars, albeit at a slow pace,” Bishop said.
In the new study, scientists conducted laboratory experiments on mixtures of sulfates, chloride salts, tiny particles of ice and volcanic ash similar to Martian soil. They froze and thawed such mixtures at the types of low temperatures found on the Red Planet.
Researchers found thin layers of muddy water formed on the surface of mineral grains. They suggested that these films could expand and contract over time, causing upheaval and contractions below the Martian surface. Wind and dust on those unstable surfaces could then trigger landslides, producing the lines seen on the Red Planet, Bishop explained.
Scientists noted that in the future, surface missions on Mars to recent RSL sites could help test their model. They detailed their discoveries online today (February 3) in the journal Science Advances.
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