Bizarre 'halos' on Mars suggest life may have existed on the red planet more recently than thought

  • Rings of silica indicate groundwater was still flowing after lakes dried out
  • Lighter-toned bedrock suggests planet had liquid for a prolonged period
  • Scientists are trying to put together a more complete picture of of Mars
  • Findings were made by NASA's Curiosity rover which was sent to find life 

By PHOEBE WESTON FOR MAILONLINE

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Mars was covered in water for far longer than previously thought meaning life could have been there remarkably recently, according to scientists.

Lighter-toned bedrock that surrounds cracks and fissures in the surface suggests the red planet had life-sustaining liquid for a prolonged period of time. 

The presence of halo-like rings of silica in rocks indicates that groundwater was still flowing within the rocks for long after the lakes dried out. 

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This is a mosaic of images from the navigation cameras on the NASA Curiosity rover shows 'halos' of lighter-toned bedrock around fractures. These halos comprise high concentrations of silica and indicate that liquid groundwater flowed through the rocks in Gale crater longer than previously believed

This is a mosaic of images from the navigation cameras on the NASA Curiosity rover shows 'halos' of lighter-toned bedrock around fractures. These halos comprise high concentrations of silica and indicate that liquid groundwater flowed through the rocks in Gale crater longer than previously believed

WHAT DID THEY FIND?

Lighter-toned bedrock that surrounds cracks and fissures in the surface suggests the red planet had liquid for a prolonged period of time. 

The presence of halo-like rings of silica in rocks indicates that groundwater was still flowing within the rocks for long after the lakes dried out. 

Scientists are using all the data collected by ChemCam to put together a more complete picture of the geological history of Mars.

They are not clear however whether this groundwater could have sustained life. 

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'The concentration of silica is very high at the centre lines of these halos', said Jens Frydenvang, a scientist at Los Alamos National Laboratory and the University of Copenhagen and lead author of the paper

'What we're seeing is that silica appears to have migrated between very old sedimentary bedrock and into younger overlying rocks', he said.  

The findings show that even when this lake evaporated substantial amounts of groundwater were present for a long time afterwards.   

'Thus, further expanding the window for when life might have existed on Mars', said Dr Frydenvang.

'The goal of NASA's Curiosity rover mission has been to find out if Mars was ever habitable, and it has been very successful in showing that Gale crater once held a lake with water that we would even have been able to drink, but we still don't know how long this habitable environment endured', he said. 

The halos were analysed by the rover's science payload, including the laser-shooting Chemistry and Camera (ChemCam) instrument, developed at Los Alamos National Laboratory in conjunction with the French space agency.

Curiosity has travelled more than 16 km (10 miles) over 1,700 sols, martian days and has gone from the bottom of the Gale crater part way up Mount Sharp, in its centre.

The presence of halo-like rings of silica in rocks indicates that groundwater on Mars (pictured) was still flowing within the rocks for long after the lakes dried out

The presence of halo-like rings of silica in rocks indicates that groundwater on Mars (pictured) was still flowing within the rocks for long after the lakes dried out

Scientists are using all the data collected by ChemCam to put together a more complete picture of the geological history of Mars.

They are not clear however whether this groundwater could have sustained life. 

The elevated silica in halos was found over approximately 20 to 30 metres (66 - 98 feet) in elevation near a rock-layer of ancient lake sediments that had a high silica content.

Dr Frydenvang added: 'This tells us that the silica found in halos in younger rocks close by was likely remobilised from the old sedimentary rocks by water flowing through the fractures.'

Specifically, some of the rocks containing the halos were deposited by wind, likely as dunes.

Such dunes would only exist after the lake had dried up.

The new finding is reported in a paper published today in Geophysical Research Letters, a journal of the American Geophysical Union.

MARS - A WET PLANET? 

Evidence of water on Mars dates back to the Mariner 9 mission, which arrived in 1971. It revealed clues of water erosion in river beds and canyons as well as weather fronts and fogs.

Viking orbiters that followed caused a revolution in our ideas about water on Mars by showing how floods broke through dams and carved deep valleys.

Mars is currently in the middle of an ice age, and before this study, scientists believed liquid water could not exist on its surface.

In June 2013, Curiosity found powerful evidence that water good enough to drink once flowed on Mars.

In September of the same year, the first scoop of soil analysed by Curiosity revealed that fine materials on the surface of the planet contain two per cent water by weight.

Last month, scientists provided the best estimates for water on Mars, claiming it once had more liquid H2) than the Arctic Ocean - and the planet kept these oceans for more than 1.5 billion years.

The findings suggest there was ample time and water for life on Mars to thrive, but over the last 3.7 billion years the red planet has lost 87 per cent of its water - leaving it barren and dry. 

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