In 2011, researchers began noticing long narrow streaks on some of the images the Mars Reconnaissance Orbiter was sending to Earth. The dark lines, which appear mainly on the edges of craters, are called recurring slope lineae, and they wax and wane throughout the Martian year, shrinking during cold weather and widening during warm periods. Last September, researchers put forward a compelling case that the lines were created by briny liquid water.
Now, a new study in the journal Nature Geosciences shows how water could boil out of the Martian soil, adding a little more bulk to that claim. Alfred McEwen, a professor of planetary geology at the University of Arizona and his colleagues conducted their study using the Large Mars Chamber at The Open University in the United Kingdom. This chamber simulates conditions on Mars, allowing researchers to control the temperature, air pressure, and nitrogen and carbon dioxide levels.
According to Michael Greshko at National Geographic, the researchers put a sloping three- by seven-foot plank covered in fine sand in the chamber. They then melted a large ice cube at the top of the ramp, recording what the meltwater did as it rolled down the slope. Under Earth-like conditions, the water crept downhill, darkening the sand along the way, but not affecting it too much.
When the researchers simulated Mars, however, the water seeped into the sand and began to boil away in the low-pressure system, creating little piles at the leading edge of the flow. Eventually the slope was covered in a series of ridges.
More at:
http://www.smithsonianmag.com/smart-news/boiling-water-could-explain-mysterious-dark-streaks-mars-180958976/
