Snow might have fallen on Mars 400,000 years in the past

Mars seems to have had liquid water on its floor as lately as 400,000 years in the past, presumably beginning as snow that melted and helped flip sand dunes into strong, cracked crusts, based on pictures taken by China’s Zhurong rover.

Plenty of proof factors in direction of Mars having had huge deposits of liquid water sooner or later in its historic previous, however how lengthy this water continued for or how a lot made it to the planet’s current previous is unclear.

Now, Xiaoguang Qin on the Chinese language Academy of Sciences in Beijing and his colleagues have discovered cracks, crusts and clumps of particles on prime of sand dunes within the Martian plain of Utopia Planitia that may solely be defined by liquid water from between 400,000 and 1.4 million years in the past.

“Sand dunes are a extra fashionable landform,” says Qin. “These crusts on the dunes’ surfaces have solidified the sand dunes and stopped them shifting.”

The presence of sure salts within the sand led the group to consider the water initially fell onto the sand dunes within the type of snow or frost, which later melted and blended with the sand to type hydrated minerals. These minerals then clumped collectively and, as soon as the water evaporated, have been cemented in place and fashioned the cracked crust seen by the rover’s digital camera.

The mechanism that Qin and his group suggest for the cracks having fashioned by a water-based cement is convincing, says Matt Balme on the Open College within the UK, however there’s nonetheless a risk that it may have fashioned by way of one other Martian geological mechanism that we aren’t conscious of on Earth, he says.

Given what number of sand dunes have been seen in different Mars missions, it is likely to be price revisiting these pictures to see if related options might be discovered, says Balme.