New Study Suggests Dark Streaks Caused by Boiling Water
Last September, a research team reported in the journal Nature Geoscience that the dark streaks running down the slopes on the Martian surface may be the result of flowing water -- a super salty brine that 'melts' during the summer month.
These 'hydrated' salt mineral require water to exist, so it wasn't long before the headlines hit.
You've seen them.
The streaks that support this theory appear during the Martian summer, extending up to a few hundred meters in length but usually no more than five meters in width , before fading as the seasons cool.
But the theory is still puzzling. How can liquid water exist in the low atmospheric pressure of Mar?. It should either freeze, or boil off -- despite the warming temperatures.
Now a team from France, Britain and the United States think they have the answer.
In a new study, these researchers, led by Marion Masse of the University of Nantes in France, constructed models and simulated Mars conditions to test the possibilities.
First, they placed a block of ice on a 30-degree plastic slope covered with loose fine-grained sand, and allowed it to melt in a chamber in which Martian pressure and summer temperatures were recreated.
Then they repeated the experiment under Earth conditions to compare the processes.
The results were remarkably similar to those observed on Mars.
Under Mars conditions, the melting ice produced a liquid that quickly boiled as it flowed down the slope before finally filtering into the sand.
The boiling effect also created a water vapor that blasted sand up and out, a popping effect that can be seen in the video below, creating steep ridges that would eventually collapse back onto themselves and form channels.
As Wouter Marra of the geosciences faculty of the University of Utrecht in the Netherlands explained:
The morphologies produced on the sandy slopes in these experiments are remarkably similar to the streaks observed on Mars. This process in which unstable boiling water causes grains to hop and trigger slope failures may underlie some of the active landforms observed on the Martian surface.
Questions remain, however.
The experiments depicted used pure water ice, but it has been speculated that the water on Mars is super-saturated with perchlorates.
Salt, in other words.
Would salty brines produce the same effect?
Maybe that's coming in the next experiment...