A group of researchers led by senior researcher at the SETI Institute Janice Bishop has put forward a theory about what causes landslides on the surface of Mars.
Scientists previously assumed that this movement was caused by streams of liquid mud or dry granular streams. However, none of the models could fully explain the seasonal features of Mars, known as repetitive slant lines (RSL).
The new work hypothesizes that melting ice in the near-surface regolith is causing surface changes that make it vulnerable to dust storms and wind. As a result, RSLs appear and/or expand on the surface of Mars.
In addition, the team believes that the thin layers of melting ice are the result of interactions between underground water ice, chlorine salts, and sulfates, which create a fluid slush that provokes sinkholes, collapse, surface currents, and uplifts.
Data from the High-Resolution Imaging Science Experiment (HiRISE) from the Mars Reconnaissance Orbiter (MRO) shows that RSLs are located on slopes facing the sun, where they continue to appear and/or expand over time.
Previous studies have suggested that RSLs are associated with chlorine salts and have noted that they are found in areas with high sulfates. The new work expands on these observations: analog field studies on Earth, such as in the dry valleys of Antarctica, the Dead Sea in Israel, and the Salar de Pajonales of the Atacama Desert, show that when salts interact with gypsum or water underground, it causes disturbances on the surface including landslides and landslides.
To test their theory, the team conducted laboratory experiments: they froze and thawed analog samples of Mars, composed of chlorine salts and sulfates, at low temperatures, such as on Mars. As a result, slushy ice of about –50°С was formed, followed by gradual ice melting from –40 to –20°С.