Strange Streaks on Mars Are Sand, Not Water

23 Novembre, 2017, 00:23 | Auteur: Therese Cote
  • Strange Streaks on Mars Are Sand, Not Water

Authors of the report propose possibilities that include involvement of small amounts of water, indicated by detection of hydrated salts observed at some of the flow sites.

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

Scientists, including those from the University of Arizona in the USA and Durham University in the United Kingdom analysed narrow, down-slope trending surface features on Mars that are darker than their surroundings, called Recurring Slope Linea (RSL).

Speaking about this research, US Geological Survey's Colin Dundas explains, "We've thought of RSL [recurring slope lineae] as possible liquid water flows, but the slopes are more like what we expect for dry sand".

"This new understanding of RSL supports other evidence that shows that Mars today is very dry", said Dundas, lead author of the study published in the journal Nature Geoscience. This is based in part on assessments made with the Mars orbiter's telescopic camera. The data include 3-D models of slope steepness using pairs of images for stereo information.

However, all of the 151 RSLs examined in the study were found to all end on similar slopes despite very different lengths.

Strange Streaks on Mars Are Sand, Not Water

One of the reasons for the change is that scientists found that RSL were only visible on steep slopes.

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".

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

"RSL probably form by some mechanism that is unique to the environment of Mars, so they represent an opportunity to learn about how Mars behaves, which is important for future surface exploration", said Alfred McEwen from the University of Arizona, Tucson, a co-author on the study.

These findings indicate that it is hard for Earth-like life to exist near the surface of Mars owing to the water-restricted conditions that exist on the planet.

SCIENTISTS have dashed hopes of Mars supporting alien life after realising the mysterious "water" marks were actually left by SAND.

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