Published: Fri, November 24, 2017
Science | By Hubert Green

NASA discovery of water on Mars was actually sand

NASA discovery of water on Mars was actually sand

The team came to this conclusion by analysing the dark, narrow, down-slope trending surface features - referred to as recurring slope lineae (RSL) - mostly found on steep rocky slopes in dark regions of Mars.

There are still unanswered questions, such as why the streaks appear and vanish with the seasons, and what makes them dark in color.

The findings published today in Nature Geoscience argue against the presence of enough liquid water for microbial life to thrive at these sites.

The scientists concluded that the range "matches that of slipfaces for active Martian and terrestrial dunes, interpreted as the range of critical angles for which granular flows of sand can terminate".

The RSL are nearly all restricted to slopes steeper than 27 degrees.

It was previously thought that this could provide evidence of water flow.

According to CNN, the new study suggested that dark streaks discovered on the red planet, previously believed to be signs of water, could actually be sand.

"The RSL don't flow onto shallower slopes, and the lengths of these are so closely correlated with the dynamic angle of repose, it can't be a coincidence", said HiRISE Principal Investigator Alfred McEwen at the University of Arizona, Tucson, a co-author of the new report. Dundas says this doesn't rule out liquid water on Mars, but it supports the idea of a cold, dry planet.

However, RSL remain puzzling.

"There is a lot of ice in the subsurface and at the poles, and deliquescent salts can draw water out of the atmosphere and form liquid under some conditions". Darkening and fading might result from changes in hydration.

On top of that, if water were present it would surely appear on the lower slopes, rather than just near the top. That's bad news in the hunt for microbes, unfortunately. But the exact process at play remains a bit of a mystery, and it's probably something quite unique to Mars.

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