Water on Mars? Mount Sharp in Gale Crater Formed by Martian Winds

When scientists discovered a 3.5-mile high mound on Mars, they thought that it might preserve evidence of a massive lake. Now, though, researchers suspect that there may be another reason for the creation of this mound. It's possible that the formation is the result of the Red Planet's dusty atmosphere rather than the evidence of water.

Known as Mount Sharp, the mound was first thought to have emerged from layers of lakebed silt. The theory was that because of this, the mound could contain evidence of the water that once covered it in the past. It's one of the reasons why NASA's Mars rover Curiosity landed near the site in August; scientists hoped that the rover would be able to collect samples and uncover evidence of the ancient lake nearby.

Now, though, it turns out that Mount Sharp was never underwater. In order to study the mound, the researchers used pairs of satellite images of the site taken in preparation for the rover landing by the High-Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter satellite. After examining these images, the scientists found that the various layers of the mound did not form flat-lying stacks, which is what would have formed if the mound were created by a lake.

So how did it form? Researchers believe that the mound emerged as strong winds carried dust and sand into the 96-mile-wide crater in which the mound sits, called the Gale Crater. It's likely that air actually rises out of the crater when the Martian surface warms during the day. Then, the air sweeps back down the walls of the Gale Crater at night. These Martian winds would have died down at the crater's center where, eventually, dust settled and gathered over many years.

While the mound may not have been underwater, it doesn't mean that there was never water in the Gale Crater. Researchers were quick to note that it was possible that there was a moat-like lake around Mount Sharp at one point.

"Our work doesn't preclude the existence of lakes in the Gale Crater, but it suggests that the bulk of the material in Mount Sharp was deposited largely by the wind," said co-author Kevin Lewis in a news release. "These sedimentary mounds could still contain millions of years of Martian climate history."

The findings are published in the journal Geology.