“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 Washington. “This is a significant development, as it appears to confirm that water — albeit briny — is flowing today on the surface of Mars.”
Lujendra Ojha of the Georgia Institute of Technology in Atlanta is the lead author of a report on these findings published on September 28 by Nature Geoscience; he discovered a first clue for water-like activity when, in 2010, he noticed certain downhill flows – known as “recurring slope lineae” (RSL) – after reviewing images and data provided by NASA’s Mars Reconnaissance Orbiter (MRO) and MRO’s High Resolution Imaging Science Experiment (HiRISE).
Analysis of a series of MRO images revealed signatures of hydrated minerals on slopes, where mysterious streaks can be seen on the Red Planet. These darkish streaks appear to ebb and flow over time; in fact, NASA research says they darken and appear to flow down steep slopes during warm seasons, and then fade in cooler seasons.
Additionally, the streaks appear in several locations on Mars when temperatures are above minus 10 degrees Fahrenheit, and then disappear again at colder times. According to NASA, “the hydrated salts would lower the freezing point of a liquid brine, just as salt on roads here on Earth causes ice and snow to melt more rapidly… it’s likely a shallow subsurface flow, with enough water wicking to the surface to explain the darkening.”
“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,” said Ojha.
These hydrated salts – likely a mixture of magnesium perchlorate, magnesium chlorate and sodium perchlorate – have been shown to keep liquids from freezing even when conditions are as cold as minus 94 degrees Fahrenheit and can also be found in deserts on Earth.
While perchlorates have previously been discovered on Mars during NASA’s Phoenix lander and Curiosity rover missions, the new study of RSL shows evidence for perchlorates in hydrated form and in different areas than those explored by the landers.
“When most people talk about water on Mars, they’re usually talking about ancient water or frozen water. Now we know there’s more to the story. This is the first spectral detection that unambiguously supports our liquid water-formation hypotheses for RSL,” said Ojha.
“It took multiple spacecraft over several years to solve this mystery, and now we know there is liquid water on the surface of this cold, desert planet,” Michael Meyer, lead scientist for NASA’s Mars Exploration Program at the agency’s headquarters in Washington, concluded, adding that, “It seems that the more we study Mars, the more we learn how life could be supported and where there are resources to support life in the future.”
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