The speculation is over: NASA’s big discovery isn’t the discovery of alien life on Mars or a promotional tie-in with the upcoming Matt Damon movie The Martian. Rather, scientists at the US space agency have found evidence that liquid water is present on the Red Planet.
The discovery, detailed in a paper published Monday in the journal Nature Geoscience, was first reported by Bloomberg and The Telegraph and centers around the detection of hydrated salts that are caused by briny water. The findings explain unusual, long streaks that sometimes show up on the planet’s terrain – features that were initially detected by NASA back in 2010.
“Our findings strongly support the hypothesis that recurring slope lineae form as a result of contemporary water activity on Mars,” lead author Lujendra Ojha from Georgia Tech and his colleagues wrote. “The presence of liquid water on Mars today has astrobiological, geologic and hydrologic implications and may affect future human exploration.”
Chemical evidence of water found in hydrated salts
While the newly-published research all but confirms the existence of liquid water on Mars, they authors didn’t stumble across large flowing rivers or streams. Rather, the “recurring slope lineae” to which they refer are dark features of precipitated salt that can be up to five meters wide and as much as 100 meters long, Bloomberg and Wired explained.
Ojha and his fellow scientists had hypothesized that these features were produced by flowing H2O, but until recently, they lacked solid mineralogical evidence to support that notion. Every Martial summer, they monitored these slope lineae as they grew wider week-by-week, only to fade when winter came. The lineae formed exactly where and when the conditions would have been right for liquid water to exist, and salt on the surface kept it from boiling or freezing.
The authors are quick to emphasize that they have not actually observed water flowing on the Red Planet. Rather, they collected data from the CRISM instrument on the Mars Reconnaisance Orbiter, which only observed the terrain every afternoon when conditions are at their hottest and driest. Any actual liquid water would have evaporated before the MRO could spot it.
As Ojha explained to Wired, though, the substance flowing on Mars “is hydrating the salt, and we’re seeing that hydration in the spectral signature.” An in-depth analysis of pixels from the CRISM instrument’s data revealed that the crystal structures of those salts (including magnesium perchlorate, magnesium chlorate, and sodium perchlorate) contained water molecules, which the website said was “pretty strong evidence that they were deposited by flowing water.”
‘Strongest evidence yet’ of liquid water on modern-day Mars
In a statement, NASA officials called the findings “the strongest evidence yet that liquid water flows intermittently on present-day Mars,” and John Grunsfeld, associate administrator at the agency’s Science Mission Directorate in Washington, said that the research provides NASA with “convincing science that validates what we’ve long suspected… it appears to confirm that water – albeit briny – is flowing today on the surface of Mars.”
“We found the hydrated salts only when the seasonal features were widest, which suggests that either the dark streaks themselves or a process that forms them is the source of the hydration. In either case, the detection of hydrated salts on these slopes means that water plays a vital role in the formation of these streaks,” added Ojha, who first noticed the features while studying as an undergraduate student at the University of Arizona five years ago.
Using both the MRO’s CRISM and High Resolution Imaging Science Experiment (HiRISE) instruments, the scientists found signatures of hydrated salts at several RSL locations, but only at times when the dark features were relatively wide. No evidence of hydrated salt could be found when the RSL were less extensive, they added. These same hydrated salts can be found naturally produced in the deserts of Earth, and some are usable as rocket propellant, NASA said..
While these salts, called perchlorates have previously been seen on Mars, those featured in the new study are the first to be identified from orbit instead of by landers such as the Phoenix and Curiosity vehicles. Also, these perchlorates are in hydrated form, and can be found in different areas than those previously studied on the surface. The discovery, Ojha noted, “unambiguously supports our liquid water-formation hypotheses for RSL.”
UPDATE: NASA answers public’s questions on Reddit AMA
On if there could be Martian life in the water since it’s only at certain times during the year:
It’s possible. We know of forms of life that hibernate during dry seasons on Earth. The water that we’re seeing within the RSL (the seasonal dark streaks that we’re seeing on slopes on Mars) is salty. Salty water could be harmful to life.
Why should the average Joe care about this?
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Feature Image: Thinkstock
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