Citizen Staff Writer
MATT LEWIS
mattl@tucsoncitizen.com
Golfers might want to move to Mars.
Imagine your ball a few inches from the hole, and then falling in. The concept is not that far-fetched on Mars.
Jon Pelletier, a University of Arizona associate professor of geoscience, said winds on Mars create small craters near softball-shaped stones due to soil erosion – and then the stones are pushed into the craters.
That’s a change from the old school of thought, which was that winds of 200 to 300 mph picked up the rocks and blew them into the craters.
The part that baffled scientists was how gale force winds could leave rocks in specific patterns as found on Mars. If it were just the winds, the rocks would be tossed around.
“It would be Hurricane Katrina-sized winds plus 10,” Pelletier said about the winds it would take to make this reality.
He said it is not possible Mars has winds of such magnitude.
That’s why, Pelletier said, it is more likely that 10- to 20-mile-per hour-winds pushed the stones over time into the craters as the soil around them eroded.
The new theory evolved after Andrew Leier, an associate professor at the University of Calgary; James Steidtmann, a retired University of Wyoming professor and Pelletier questioned the theory of extremely high winds doing the trick.
Leier and Steidtmann began by studying different conditions in a wind tunnel.
When Steidtmann first tested stones in a wind tunnel, only one stone at a time was tested.
The scientists eventually put a group of stones together and discovered the craters were no longer created in front of the stones but at slight degree to the side.
That caused the rocks to roll away from each other and arrange themselves in what appeared to be an organized fashion.
Pelletier then began modeling Steidtmann’s research and applied it to Mars.
According to Pelletier, the stones were not thrown by solar winds, but rather moved through the erosion of the soil around the round, coarse stones.
Pelletier plans to expand the scope of hisresearch. He will be submitting a proposal to NASA to study how land forms known as yardangs are formed. Yardangs are ridges formed from wind abrasion and are comparable to A-Mountainin Tucson.
Pelletier’s research was published in the January edition of the journal “Geology.”
UA prof has new explanation for stones in Mars craters