How Do You Like Your Dunes?

“Two sizes of ripples are evident in this Dec. 13, 2015, view of a top of a Martian sand dune, from NASA's Curiosity Mars rover”.

Credits: NASA/JPL-Caltech/MSSS

Photographs taken by the Mars Curiosity Rover at the "Bagnold Dunes", six months ago, reveal active sand dunes. Scientists have determined that Mars has dry sand ripples similar to the ripples seen under Earth’s oceans. "Earth and Mars both have big sand dunes and small sand ripples, but on Mars, there's something in between that we don't have on Earth," said Mathieu Lapotre, a collaborator for the Curiosity mission.

Although real sand dunes can be found on both planets, the ripples on Mars were thought to be much larger than those on Earth, until the recent discovery. Due to these technological advances and high resolution images, we can now see the true size of the ripples and how they strongly resemble ripples underwater on Earth. "The size of these ripples is related to the density of the fluid moving the grains, and that fluid is the Martian atmosphere," said Lapotre. "We think Mars had a thicker atmosphere in the past that might have formed smaller wind-drag ripples or even have prevented their formation altogether. Thus, the size of preserved wind-drag ripples, where found in Martian sandstones, may have recorded the thinning of the atmosphere."

Researchers conclude that the meter-scale ripples are built by Martian wind dragging sand particles the way flowing water drags sand particles on Earth. These discoveries prove that Mars lost most of its original atmosphere early in the planet's history. After examining the dune field, the next Curiosity mission is to investigate evidence about how and when ancient environmental conditions in the area changed from habitable to inhabitable.

Biology Team 1: Jennifer Bahamonde, Octavio Fernandez, Gabriela Morey

Source:

Webster, Guy, and Robert Perkins. "NASA Rover's Sand-Dune Studies Yield Surprise." NASA. Ed. Tony Greicius. NASA, 30 June 2016. Web. 19 July 2016. <http://www.nasa.gov/feature/jpl/nasa-rovers-sand-dune-studies-yield-surprise>.