Cracked mud on Mars - Latest images from NASA's Curiosity rover reveal new evidence of water (See pic)

Image credits: NASA/JPL-Caltech/MSSS

New Delhi: Latest images from NASA's Curiosity Mars rover suggest a network of cracks in the Martian rock slab called 'Old Soaker' that may have formed from the drying of a mud layer more than 3 billion years ago.

Scientists used Curiosity rover in recent weeks to examine slabs of rock cross-hatched with shallow ridges that likely originated as cracks in drying mud.

"Mud cracks are the most likely scenario here," said Curiosity science team member Nathan Stein. He is a graduate student at Caltech in Pasadena, California, who led the investigation of a site called "Old Soaker," on lower Mount Sharp, Mars.

NASA says if this interpretation holds up, these would be the first mud cracks - technically called desiccation cracks - confirmed by the Curiosity mission. They would be evidence that the ancient era when these sediments were deposited included some drying after wetter conditions.

Curiosity has found evidence of ancient lakes in older, lower-lying rock layers and also in younger mudstone that is above Old Soaker.

"Even from a distance, we could see a pattern of four- and five-sided polygons that don't look like fractures we've seen previously with Curiosity," Stein said. "It looks like what you'd see beside the road where muddy ground has dried and cracked."

The cracked layer formed more than 3 billion years ago and was subsequently buried by other layers of sediment, all becoming stratified rock.

A different type of cracking with plentiful examples found by Curiosity occurs after sediments have hardened into rock.

Both types of crack-filling material were found at Old Soaker. This may indicate multiple generations of fracturing: mud cracks first, with sediment accumulating in them, then a later episode of underground fracturing and vein forming.

"If these are indeed mud cracks, they fit well with the context of what we're seeing in the section of Mount Sharp Curiosity has been climbing for many months," said Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory in Pasadena.

Besides the cracks that are likely due to drying, other types of evidence observed in the area include sandstone layers interspersed with the mudstone layers, and the presence of a layering pattern called cross-bedding.

Curiosity, which landed on Mars on August 6, 2012, as part of NASA's Mars Science Laboratory mission, is a car-sized robotic rover exploring Gale Crater on the Red Planet. The main goal of the mission is to determine if Mars was ever able to support microbial life.