Friday, May 11, 2012

Surprise: Martian sand dunes are speedy

Rare winds jump-start sand movement on Mars, according to scientists.

Towering sand dunes on Mars, once thought to be ancient and unchanging, are actually dynamic and active today, new satellite observations show.

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Using advanced optical images taken by the High Resolution Imaging Science Experiment (HiRISE) on NASA's Mars Reconnaissance Orbiter, scientists tracked the horizontal and vertical motion of sand over time with unprecedented detail.

"We can actually see movement, potentially, of just a few centimeters," planetary geologist Nathan Bridges of Johns Hopkins University told

Bridges and his team studied the Nili Patera dune field just north of the Martian equator, taking detailed, high-resolution images over 105 days.

Using a computer program previously used to examine earthquakes and landslides on Earth, the scientists measured movements of the dunes, finding that some of the surface ripples traveled as much as 15 feet (4.5 meters) over the course of the study.? Fast dunes may travel a distance equal to their length over 170 years, while slower dunes take a few thousand years to move. [Video: Sand Dunes Crawl Across Mars' Surface]

Interestingly, the dunes in the Nili Patera move similarly to those in Victoria Valley, Antarctica, on Earth.

Bridges previously worked on a 2010 study that first identified Martian dune motion in the Nili Patera region. So when he wanted a more detailed look at sand dunes, the region seemed like a good place to start.

"We thought, let's test this technology on an area where we know the motion is occurring," Bridges said.

Located on a volcanic feature inside the Syrtis Major region, Nili Patera is a crater with an opening at one end that allows dunes to blow inside of it. However, this area of Mars isn't likely to be unique.

"There's no reason to think that we would not see this in some other areas of Mars, as well," Bridges said.

The researchers intend to examine the dune and ripple motion on other areas of Mars, including regions where the motion may not be obvious without their technique.

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