Let’s Go Get Duned. Or More Precisely, Draaed — on Mars!

By Tom Yulsman | June 7, 2014 1:50 pm

This beautiful sandy landform on Mars, called a “draa,” was imaged by the HiRISE instrument aboard NASA’s Mars Reconnaissance Oribter on on Jan. 6, 2014. (Source: NASA)

To my eye, the image above looks like a beautiful work of art — something I could easily see hanging in a gallery.

If a photographer had taken it, I don’t think many would disagree with that characterization. And in a sense, a photographer did take it — just not a human one.

What you’re looking at is an image acquired by the HiRISE instrument on NASA’s Mars Reconnaissance Orbiter. HiRISE stands for “High Resolution Imaging Science Experiment,” and since 2006 it has imaged hundreds of swaths of the surface of the Red Planet in unprecedented detail.

This image from HiRISE shows a fascinating feature called a “draa” in Juventae Chasma, a large depression 16,000 feet below the surrounding terrain. A draa is sandy landform larger than a dune. Its wavelength — meaning from crest to crest — is greater than 1 kilometer.

Just as a dune has a rounded aspect on its windward side, and a steep face called a “slipface” on its downwind side, so does a draa. The dark crease running across the image is the shadow cast by the towering slipface of the draa, which is probably hundreds of meters high.

You can also see a number of features superposed by Martian winds on the draa: ripples, transverse eolian ridges, and dunes.

This video offers a beautiful visual tour of these features, and an explanation of each one.

CATEGORIZED UNDER: Planetary Science, select, Top Posts


ImaGeo is a visual blog focusing on the intersection of imagery, imagination and Earth. It focuses on spectacular visuals related to the science of our planet, with an emphasis (although not an exclusive one) on the unfolding Anthropocene Epoch.

About Tom Yulsman

Tom Yulsman is Director of the Center for Environmental Journalism and a Professor of Journalism at the University of Colorado, Boulder. He also continues to work as a science and environmental journalist with more than 30 years of experience producing content for major publications. His work has appeared in the New York Times, Washington Post, Audubon, Climate Central, Columbia Journalism Review, Discover, Nieman Reports, and many other publications. He has held a variety of editorial positions over the years, including a stint as editor-in-chief of Earth magazine. Yulsman has written one book: Origins: the Quest for Our Cosmic Roots, published by the Institute of Physics in 2003.


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