Mars pebbles travelled 50 km down a riverbed

Washington: While the world celebrates the signs of flowing water on Mars, researchers estimate that the Martian pebbles travelled roughly 50 km from their source, supporting the idea that Mars once had an extensive river system and conditions that could harbour life.

Douglas Jerolmack, geophysicist at University of Pennsylvania, and his collaborator Gabor Domokos have devised the first-ever method to quantitatively estimate the transport distance of river pebbles from their shape alone.

"Thousands of years ago, Aristotle pondered the question of pebbles on the beach and how they become rounded,” Jerolmack said.

"But until recently, descriptions of pebble shape have been qualitative, and we lacked a basic understanding of the rounding process,” he added.

With lab and field data in hand, the team turned to the extraterrestrial. Using publicly available images of rounded pebbles on Mars from the Curiosity rover mission, they traced their contours and performed an analysis based on the models the team had established.

The results suggested that the pebbles had lost approximately 20 percent of their volume.Applying further calculations to the basalt material found on Mars,

they arrived at the calculation that the pebbles had travelled an estimated 50 km from their source.