History of Mt. Sharp Challenged: Wind, Not Water, Formed Martian Mountain

Mt. Sharp, the 3.5-mile high Martian landmass and destination of the Curiosity rover, may have been formed by winds carrying dust and sand across the Red Planet, according to new research from Princeton University and California Institute of Technology. If correct, the research would upend the long-standing belief that Mt. Sharp was formed from layers of lakebed silt and is the remnant of an evaporated body of water.

The mountain stands in the middle of the 96-mile wide Gale Crater. The researchers believe that air blown into the massive crater loses its velocity towards the center of the crater and deposits dust and sand particles which over time developed a mound of red dirt nearly the size of Alaska's Mt. McKinley.

If correct, the revelation would be a blow to the currently held belief that Mar's landscape was more Earth-like in the past.

The mountain was likely never under water, though a body of water could have existed in the moat around the base of Mount Sharp, said study co-author Kevin Lewis, a geoscientist at Princeton.

"Our work doesn't preclude the existence of lakes in Gale Crater, but suggests that the bulk of the material in Mount Sharp was deposited largely by the wind," said Lewis in a Princeton news release.

"Every day and night you have these strong winds that flow up and down the steep topographic slopes. It turns out that a mound like this would be a natural thing to form in a crater like Gale," Lewis said. "Contrary to our expectations, Mount Sharp could have essentially formed as a free-standing pile of sediment that never filled the crater."

While the waterless viewpoint may be viewed by some an interplanetary disappointment, Lewis was still upbeat.

"These sedimentary mounds could still record millions of years of Martian climate history," Lewis said. "This is how we learn about Earth's history, by finding the most complete sedimentary records we can and going through layer by layer. One way or another, we're going to get an incredible history book of all the events going on while that sediment was being deposited. I think Mount Sharp will still provide an incredible story to read. It just might not have been a lake."

The photo above shows how air would have flowed up the crater rim (red arrows) and the flanks of Mount Sharp (yellow arrows) in the morning when the Martian surface warmed, and reversed in the cooler late afternoon. The researchers created a computer model showing that the fine dust carried by these winds could accumulate over time to build a mound the size of Mount Sharp even if the ground were bare from the start. The blue arrows indicate the more variable wind patterns on the floor of the crater, which includes the Curiosity landing site (marked by the "x").