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Hale Crater

Signs of water on Mars

Hale Crater, on Mars: saltwater flow may have created dark streaks along mountain slopes

NASA / JPL / University of ArizonaHale Crater, on Mars: saltwater flow may have created dark streaks along mountain slopesNASA / JPL / University of Arizona

It was long awaited news. Data collected by the Mars Reconnaissance Orbiter spacecraft (MRO) have confirmed that liquid water may run periodically over the surface of Mars. The announcement was made by NASA on September 28, 2015. Slope lineae – the dark, narrow streaks that appear along the slopes of mountains and canyons during the Martian summer, when temperatures rise above zero Celsius – may be marks left behind by brine flows. An instrument onboard the MRO detected chemical signatures of certain hydrated salts (magnesium perchlorate, magnesium chlorate, and sodium perchlorate) in slope lineae at four different locations near the red planet’s equator. These salts only form in the presence of liquid water (Nature Geoscience, September 28, 2015). The slope lineae become darker and seem to “move downhill” during the warmer seasons. In colder periods, they disappear. Ever since their discovery in 2010, slope lineae were thought to be associated with the presence of liquid water, which was abundant on Mars in the distant past. But there was no solid evidence. Former astronaut John Grunsfeld, Associate Administrator for the Science Mission Directorate at NASA, says that the new scientific evidence is compelling. These signs of liquid water on Mars rekindle expectations that our red neighbor, though frigid and desolate now, may one day harbor some form of life.