Scientists have found new evidence that Mars was once home to a lake, raising the chances that the red planet could have housed life.
Nasa’s Curiosity rover found clues to Mars’ watery past in the form of rippled rock textures that suggest lakes existed in a region of ancient Mars that scientists expected to be drier.
‘Billions of years ago, waves on the surface of a shallow lake stirred up sediment at the lake bottom,’ said Nasa in a statement.
‘Over time, the sediment formed into rocks with rippled textures that are the clearest evidence of waves and water that Nasa’s Curiosity Mars rover has ever found.’
Last year, Nasa’s Curiosity rover found evidence that lakes once covered a region of Mars.
So Curiosity’s team was surprised to discover the mission’s ‘clearest evidence yet’ of ancient water ripples that formed within lakes.
‘This is the best evidence of water and waves that we’ve seen in the entire mission,’ said Ashwin Vasavada, Curiosity’s project scientist at Nasa’s Jet Propulsion Laboratory in Southern California.
‘We climbed through thousands of feet of lake deposits and never saw evidence like this – and now we found it in a place we expected to be dry,’
Since 2014, the rover has been ascending the foothills of Mount Sharp, a 5-kilometre-tall mountain that was once laced with lakes and streams that would have provided a rich environment for any microbial life that could have existed on Mars.
Having climbed nearly a half-mile above the mountain’s base, Curiosity found these rippled rock textures preserved in what’s nicknamed the ‘Marker Band’ – a thin layer of dark rock that stands out from the rest of Mount Sharp.
This rock layer is so hard that Curiosity hasn’t been able to drill a sample from it despite several attempts.
Far ahead of the Marker Band, scientists can see another clue to the history of Mars’ ancient water in a valley named Gediz Vallis which is thought to have been eroded by a small river.
Scientists suspect wet landslides also occurred here, sending car-size boulders and debris to the bottom of the valley.
Not far from the rippled textures, Nasa has found rocks made of layers suggest that the Red Planet had seasons that changed periodically.
‘The wave ripples, debris flows, and rhythmic layers all tell us that the story of wet-to-dry on Mars wasn’t simple,’ Vasavada said.
‘Mars’ ancient climate had a wonderful complexity to it, much like Earth’s.’
Last year, researchers found clear evidence of a 3.5 billion-year-old shoreline around 900 metres thick, which covered thousands of square kilometres, using topography data.
Rocks collected by the Curiosity rover were also found to contain organic carbon which may have come from bugs that once roamed Mars.
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