High-resolution image of a landslide on the rim of Krupac crater on Mars.
Dark lines often appear on the surface of Mars, disappear after a period of Time, and then reappear again. This regularity is one of several mysterious features on Mars.
The Mars Orbiter’s high-resolution camera has seen that such lines are always located on sunny slopes on Mars and can be several hundred meters long. Scientists refer to them as Recurring Slope Lineae (RSLs). Previously scientists thought they were surface flowing water, or landslides formed by quicksand.
The nonprofit Search for Extraterrestrial Civilizations Institute (SETI Institute) has come up with a new theory, suggesting that the melting of ice slag in the shallow soil layers near the surface has changed the composition of the surface soils, making them more susceptible to color changes from dust storms and high winds, and giving them a streak-like appearance.
Researchers believe that a thin layer exists very shallowly beneath the Martian surface, where ice slag melts and loosens as it interacts with chlorinated salts and sulfides, forming a fluid mud. The researchers speculate that the various sinkholes, sunken terrain, sliding mud and some raised terrain seen on the surface of Mars are the result of this thin layer of mud underground.
I’m excited about the prospect of this new theory,” said Janice Bishop of the Institute for the Search for Extraterrestrial Civilizations, “that a thin layer of soil mixed with ice slag and chlorinated salts exists on the near surface of Mars and is the source of a small area of liquid water on Mars. This presents a completely new perspective on the study of chemically active processes within the shallow Martian soil layer.”
Previous studies have only known such patterns to be associated with soils with chlorinated salts, or often on raised terrains with high sulfate content. This study builds on that, combining observations of near-surface frozen salt compound activity with modeling analysis to obtain this further theory.
The researchers also sampled mixtures of simulated Martian soils in the laboratory and examined them in their frozen and thawed state. They saw these samples form a frozen slurry at minus 50 degrees Celsius and gradually thaw between minus 40 and minus 20 degrees Celsius.
The study was published Feb. 3 in the journal Science Advances.
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