New Study Unravels Source of Pebbles on Mars

New study unravels source of pebbles on Mars, just weeks after the news that Mars may be harboring liquid water under the surface.

For now, the red planet remains an arid, dry place, not too hospitable and showing no signs of life. However, images beamed back by Mars Curiosity rover in 2012 show that the surface of Mars was once cut by flowing water streams. The perfectly rounded pebbles visible in the images remain the only memory of the ancient riverbed.

However, this data was not sufficient for a scientific team looking to understand what pinpoints the natural history of those pebbles. Gabor Domokos, mathematician with the Budapest University of Technology and Economics and Douglas Jerolmack, geophysicist with the University of Pennsylvania are the enthusiastic lead authors of the breakthrough paper.

Their question needed the perfect tools to be answered. As such, Domokos set out to create the mathematical pinning of their scientific undertake. The main source of inspiration was the pebble’s shape. The findings are published in the Nature Communications journal and stand for the first method to deduct how far along pebbles are transported simply by using their shape.

After methodic research, the research team spearheaded by the two scientists reached the conclusion that the pebbles seen in the images beamed back by Mars Curiosity rover had traveled for 30 miles from their source. This finding adds to the growing body of evidence that Mars once supported an extensive river system, as well as harbored the conditions for life.

“An object’s shape can itself tell you a lot. If you go to the beach, natural history is written underneath your feet. We started to understand that there is a code that you can read to begin to understand that history”.

For earthly rocks and pebbles, we already know that the way their shape evolves is impacted by a number of factors, including abrasion against other rocks embedded in the riverbed. Abrasion from the force the water exerts, as well as from other rooks defines a smoother shape, often rounded. Linking the resulting shape with the lost mass of the rock or pebble and its transportation history becomes the trickier part. Particularly for Martian rocks on which there is not much data.

How to deduct lost mass from a pebble’s shape alone?

Working with the only measurement at hand, that is the Martian pebbles’ shape, Gabor Domokos found the formula that determines how two particles influence each other regardless of the environment they are in or their composition.

The first step to test the formula and theory was to roll limestones in a drum and record lost mass and any shape changes. As this experiment yielded results consistent with the curve provided by the formula, the research team moved on to test it in a real-life environment. In Puerto Rico, pebbles in a mountain river subject to analysis yielded the same results.

The third step was to scan the Mars Curiosity rover images and perform the same analysis based on the contours introduced in a couple of computer models.

When they found that the Martian pebbles had lost 20 percent of their mass throughout their travelling, the research team also calculated the distance from the source. It took 30 miles for the pebbles to lose 20 percent of their volume under gravity conditions on Mars.

Photo Credits: Wikimedia