It’s Official: Mars Has Liquid Water

September 28, 2015 | Sarah Tse

recurring slope lineae (RSL) flowing downhill on Mars are inferred to have been formed by contemporary flowing water.
Photo credit: NASA / JPL / University of Arizona

Mars has teased us with traces of water for years now, but there’s finally evidence of liquid water flowing across its present-day surface — and with it, a real potential to find living, breathing Martians.

Liquid, life-giving water exists on Mars, according to the newest findings from NASA’s Mars Reconnaissance Orbiter (MRO). Researchers have found the strongest evidence yet to support the presence of salty water on the planet’s present-day surface.

We’ve known for years now that Mars has ice at its poles, and suspected that the planet once hosted liquid oceans in its warmer past. But the discovery of flowing water on the present-day surface will now completely transform our approach towards studying Mars — especially the search for alien life. Whereas previous attempts to locate Martian life focused on finding ancient traces and fossils embedded in ice, scientists can now dare to dream of finding live organisms sustained by the planet’s water supply.

SEE ALSO: Enormous Underground Ice Sheet Discovered on Mars

“Our quest on Mars has been to ‘follow the water,’ in our search for life in the universe, and now we have convincing science that validates what we’ve long suspected,” said John Grunsfeld, astronaut and associate administrator of NASA’s Science Mission Directorate, in a press release.

The evidence comes from MRO’s imaging spectrometer, which picked up signatures of hydrated minerals among the dark streaks on Martian slopes that had mystified astronomers for some time. The dark streaks were first spotted in 2010, using MRO’s High Resolution Imaging Science Experiment. The dark streaks, called recurring slope lineae (RSL) only appeared in the summer, grew wider as temperatures increased, and then disappeared again come winter. This tipped off scientists that water likely had something to do with the RSL’s seasonal appearance.

Now, the association of hydrated salts with these RSL confirms the link to liquid water. A chemical analysis of the salts showed that their crystal structures contained water molecules. Basically, this means the RSL are stains formed by salty tears that flowed down Martian slopes. According to the authors of the study, a shallow subsurface flow of water would wick enough fluid to the surface to cause the darkening.

Just like on Earth, salts help lower the freezing point of water, causing it to melt at a lower temperature than normal. The variety of salts found in the RSL’s spectral signature — called perchlorates — can prevent liquids from freezing even when temperatures drop to -70 degrees Celsius. The spectrometer could only detect the hydrated salts when the RSL reached their darkest and widest point during the warmer Martian summer, but even the intermittent presence of liquid water is better than none at all.

With this confirmation of liquid water, we’ve definitely abolished Mars’s previous reputation as a cold, desert planet. Now that we know where and when to find liquid water, we can narrow down our search for lifeforms and redefine the planet’s potential for future manned missions.


Based on materials provided by NASA.

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