NASA’s Curiosity Rover has found a span of average sized sand waves which is peculiar from any sand types on Earth. The sand dunes found on Mars have three kinds’ of ripples.

Those on dry land on Earth only show two kinds of ripples.The details can be seen in a paper published online on 1 July 2016 in the journal Science.

The two sizes of the ripples are evident from the picture taken by the rover on December 13, 2015. The sand dunes of the smaller type are present on Earth. However, the larger ripple which is roughly 3 meters apart is not seen on Earth.

The pattern of ripples tells us a lot about the geological past of the red planet. The recently discovered Bagnold Dunes are located on the northwestern flank of   Mount Sharp.

The ripples found on the Martian sand dunes have been sculpted by the wind and are of two types. Ripple size depends on upon the density of the fluid moving the grains.  In this case, the fluid is the Martian atmosphere.

Experts believe that the planet h ad a thicker atmosphere in the past which formed smaller wind drag ripples or might have prevented the formation altogether. Therefore the size of the ripples formed on the Martian sand stones could be a record of the thinning of the atmosphere.

Scientists have examined the ripple textures preserved in sandstone more than 3 billion years old at the sites visited by Curiosity and Opportunity rovers. They compared the ripples with the dunes which have been formed in modern times. The ripples were almost similar to the ancient ones. It conforms to the theory that Mars had lost its atmosphere rather early in its years of existence.

Findings of Curiosity and Opportunity rovers also reveal that beneath the dusty surface of the red planet are substantial deposits of manganese dioxide. It is formed in the presence of water and atmospheric oxygen. Manganese is a relatively inert metal and requires large quantities of water and oxygen leading to the theory that the planet must have harbored significant amounts of water and oxygen in the past. It is an important consideration for any plans to inhabit and colonize the planet in the future.