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NASA recently announced that they have found signs of flowing water on Mars. How did they manage to collect the required information to make such claims, and how reliable is that information?

Robert Walker, Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.

Answered Oct 6, 2015

They found spectra of hydrated magnesium perchlorate. The perchlorates themselves are not a big deal, common on Mars. But hydrated means somehow they absorbed water. Again that's not so very remarkable as these salts can absorb water from the atmosphere. But the thing is that these hydrated salts only become hydrated in late summer when the Recursive Slope lineae are at their broadest.

Sadly

The CRISM spectrometer has a resolution of 18 meters per pixel at most accurate, while the dark streaks are a maximum of 5 meters wide, dsown to the maximum resolution, 30 cm, of the optical imaging.
CRISM's mapping orbit means it can only observe at 3 pm local time, when the streaks are likely to be at their driest.

So, the evidence is a bit indirect. Still, the only models to date of these particular seasonal streaks involve flowing water. One of the big mysteries was that they had never observed evidence of this water from orbit due to those two challenges. Now they have. Even though it is indirect, this is seen as pretty much conclusive evidence of water associated in some way with the RSLs, Whether cause, effect, or common cause is another matter. For instance, could be the perchlorates are picked up from the soil by the RSLs - or could be they are part of the explanation of how they form. Nobody can say at this point. What causes them remains one of the mysteries, also what distinguishes them from other similar slopes without streaks. But all the models for them involved flowing water already. Add this new data and they reckon pretty much a slam dunk case for flowing water, though they can't yet observe the water flowing directly.

More here: Why Are Hydrated Salts A Slam Dunk Case For Flowing Water On Mars? And What Next?

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About the Author

Robert Walker

Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.

Studied at Wolfson College, Oxford

Lives in Isle of Mull

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