Streaks discovered on Mars last year could actually have been caused by liquid water, according to a new study. The streaks were discovered by NASA’s Mars Reconnaissance Orbiter spacecraft.
Researchers believe that the melting and evaporation of frozen salty water could explain the mysterious dark streaks, reports NBC News. The lines extend down some Martian slopes during the Red Planet’s warmer months, then they fade right before winter.
Lead author Vincent Chevrier of the University of Arkansas stated:
“In one day we could form enough liquid to create these flow features on the surface.”
Chevrier and his co-author Edgard Rivera-Valentin, who works at Brown University, studied the behavior of water-and-salt mixtures, called brines, ultimately coming to the conclusion that this is what created the lines on Mars.
Because salts can lower the melting point of water, they could conceivably flow on the Red Planet’s freezing surface. The researchers used different forms of salt in their model to find one that exhibits the same behavior they saw on the alien planet.
CBS News notes that Chevrier explained, “We had to find a salt-water mixture that would come and go.” They determined through their research that calcium chloride fit perfectly.
The researchers were able to melt enough calcium chloride brine that it wasn’t able to evaporate immediately, leaving some liquid behind. This created the same flow features discovered by the MARS orbiter.
Chevrier explained that the model fits, because it explains why the streaks (known as Recurring Slope Lineae) occur seasonally and only on equator-facing slopes. It also explains why previous imaging spectrometry on Mars has not identified water signatures in these places.
NASA’s Spirit and Opportunity rovers have already found signs that water used to flow across many parts of the Red Planet billions of years ago. Curiosity even rolled past an ancient streambed just last month.
The new study about the mysterious streaks on Mars will b published in the journal Geophysical Research Letters.