The shape of some Martian pebbles suggests these rocks once rolled dozens of miles down a river, hinting that ancient Martian waterways were stable and not merely ephemeral streams, researchers say.
NASA’s Mars rover Curiosity discovered the small, round stones near its landing site in Gale Crater on the Red Planet in 2013. Researchers previously determined that these stones resemble those found in rivers on Earth, which become round as they slide, roll and hop down riverbeds and scrape other rocks.
Now, a new study suggests the Martian rocks rolled in the river for quite a while — a finding that should help scientists reconstruct what ancient Mars was like and shed light on the Red Planet’s past potential to support life, study team members said.
“We believe liquid water is a principal ingredient for life,” study co-author Douglas Jerolmack, a geophysicist at the University of Pennsylvania in Philadelphia, told Space.com. “Knowing whether pebbles in a river moved 1 kilometer or 100 kilometers [0.6 miles or 62 miles] could tell us how stable water was on the surface of ancient Mars.”
The researchers developed a mathematical model to deduce how blocky rocks become rounder and smoother as bits of them chip off due to erosion. Then, the investigators analyzed the shape of the Martian pebbles to estimate the amount of mass each lost due to erosion.
“An object’s shape can itself tell you a lot,” study co-author Gábor Domokos, an applied mathematician at the Budapest University of Technology and Economics, said in a statement today (Oct. 13). “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.”