Mars explorers reveal surprises about past and present water on the Red Planet

New findings from the Mars Curiosity rover and the Mars Reconnaissance Orbiter are showing that watery environments on Mars have existed for more recently and for longer periods of time in the planet's past, and indeed may even still exist today.

Scientists at the annual meeting of the American Geophysical Union (AGU) this week presented findings from the Mars Curiosity rover, following up on the discoveries that Mars once had a warmer, wetter environment in the past and that it was an environment that could have supported life. These new results, obtained by drilling down into the clay deposits of what is now an extinct freshwater lake — called Lake Gillespie — showed that the lake was around much later in Mars' development than previously thought, and it stuck around for much longer too, perhaps tens of millions of years. That would have given ample time for the clay to form, and also (possibly) for simple microbes to develop in the nutrient-rich environment.

"This habitable environment existed later than many people thought there would be one," said Curiosity mission scientist John Grotzinger, according to NASA. "This has global implications."

The Curiosity team also analyzed sediments drilled out from the lake bed and found abundant signs of organic carbon. They've had issues with these kinds of findings in the past, with contamination from perchlorates in the Martian soil and from the rover's instruments as well. However, by running repeated tests and analysis, the scientists have found that contamination can only account for, at most, around 3 per cent of the carbon they're seeing. Where is the other 97 percent from? It could be from organic elements raining down on the planet from space. This happens all the time, from meteorites and space dust (just like it does here on Earth). However, it could also be leftover from organic life forms — tiny rock-eating microbes that lived on the planet in the distant past.

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Also, some of the latest results from the Mars Reconnaissance Orbiter (MRO) have shown strange-looking streaks through the Martian soil that occur seasonally, and may be an indication that water is free-flowing on the planet's surface at times. Streaks like these have been seen before at mid-latitudes, but this is the first indication of them happening near the equator.

"The equatorial surface region of Mars has been regarded as dry, free of liquid or frozen water, but we may need to rethink that," said Alfred McEwen, the principal investigator for MRO's High Resolution Imaging Science Experiment (HiRISE) camera, said in a NASA statement.

Speaking at the AGU conference and presenting a paper published in Nature Geoscience on Tuesday, the science team showed evidence of these streaks forming in equatorial regions, specifically on the slopes of hills, craters and mountains that face more towards the equator — thus getting the most sunlight during the local spring and summer seasons. Although they acknowledge that there are other possible reasons for the streaks to form, they reported that the best way to explain them was that salty water was flowing down the slopes. This finding and the future findings of the HiRISE team could help Mars explorers or colonists in years to come locate water resources on the planet's surface.

"The more we find, the more we can fill in a global map of where ice is buried," Colin Dundas of the U.S. Geological Survey said in the NASA statement.

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The AGU Fall meeting runs from December 9th to 13th, and is held in San Francisco, California this year. Scientists from around the world are meeting there to discuss new research, covering not just here on Earth and the planet Mars, but topics dealing with our entire solar system. With two and a half days left in the conference, more important discoveries will no doubt be making headlines before the week ends.

(Images courtesy: NASA/JPL-Caltech/MSSS/Univ. of Arizona)

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