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Curiosity rover reaches Martian sand dunes

The rippled surface of the first Martian sand dune ever studied up close fills this Nov. 27, 2015, view of "High Dune" from the Mast Camera on NASA's Curiosity rover. This site is part of the "Bagnold Dunes" field of active dark dunes along the northwestern flank of Mount Sharp. Credit: NASA/JPL-Caltech/MSSS

The rippled surface of the first Martian sand dune ever studied up close fills this Nov. 27, 2015, view of “High Dune” from the Mast Camera on NASA’s Curiosity rover. This site is part of the “Bagnold Dunes” field of active dark dunes along the northwestern flank of Mount Sharp. Credit: NASA/JPL-Caltech/MSSS

NASA’s Curiosity rover is studying sand dunes towering up to two stories tall, returning new images showing a rippled landscape that represents a case of still-active geology on the red planet.

The six-wheeled robot recently arrived at a feature named “High Dune” to begin the dune campaign. High Dune is part of a dune system scientists have dubbed Bagnold Dunes along the northwestern flank of Mount Sharp, a three-mile-high mountain inside Gale Crater, Curiosity’s landing site.

The Bagnold Dunes are named for Ralph Bagnold, a British military engineer who pioneered research into how winds transport sand grains in the early 20th century.

See a larger mosaic showing fine details of the dunes taken by Curiosity’s Mastcam camera Nov. 27.

NASA says the lighting of the images was adjusted to approximate how the dunes would appear in daytime on Earth.

This view shows grains of sand where NASA's Curiosity Mars rover was driven into a shallow sand sheet near a large dune. The disturbance by the wheel exposed interior material of the sand body, including finer sand grains than on the undisturbed surface. Sunlight is coming from the left. The scene covers an area 1.3 inches by 1.0 inch (3.3 by 2.5 centimeters). This is a focus-merge product from Curiosity's Mars Hand Lens Imager (MAHLI), combining multiple images taken at different focus settings to yield sharper focus at varying distances from the lens. The component images were taken on Dec. 3, 2015, during the 1,182nd Martian day, or sol, of Curiosity's work on Mars. Credit: NASA/JPL-Caltech/MSSS

This view shows grains of sand where NASA’s Curiosity Mars rover was driven into a shallow sand sheet near a large dune. The scene covers an area 1.3 inches by 1.0 inch (3.3 by 2.5 centimeters). This is a focus-merge product from Curiosity’s Mars Hand Lens Imager (MAHLI), combining multiple images taken at different focus settings to yield sharper focus at varying distances from the lens. The component images were taken on Dec. 3, 2015, during the 1,182nd Martian day, or sol, of Curiosity’s work on Mars. Credit: NASA/JPL-Caltech/MSSS

The rover will spend at least several weeks at the dune site, using its wheels to dig into the sand and reveal the textures lying underneath the wind-blown surface. Curiosity will also scoop up sand for delivery into the rover’s internal laboratory, according to NASA.

Pits formed in the tracks of Curiosity’s wheels revealed finer sand grains than visible on the dune’s surface, where winds blow away the smallest particles, leaving the larger grains.

Curiosity is the first spacecraft to study active sand dunes on another planet.

Observations from NASA’s Mars Reconnaissance Orbiter, flying several hundred miles above the red planet, show the dunes are moving about 3 feet, or a meter, every year, scientists said.

A wheel track left by NASA's Curiosity Mars rover exposes underlying material in a shallow sand sheet in this Dec. 2 view from Curiosity's Mast Camera (Mastcam). The site is close to a large sand dune of similarly dark sand grains. Credit: NASA/JPL-Caltech/MSSS

A wheel track left by NASA’s Curiosity Mars rover exposes underlying material in a shallow sand sheet in this Dec. 2 view from Curiosity’s Mast Camera (Mastcam). The site is close to a large sand dune of similarly dark sand grains. Credit: NASA/JPL-Caltech/MSSS

Researchers believe dunes on Mars behave differently than they do on Earth. The surface pressure on Mars is about six-tenths of one percent the pressure on Earth, with Martian gravity three times weaker than Earth’s.

“These dunes have a different texture from dunes on Earth,” said Nathan Bridges from the Johns Hopkins University’s Applied Physics Laboratory, co-leader of the dune campaign planning team. “The ripples on them are much larger than ripples on top of dunes on Earth, and we don’t know why. We have models based on the lower air pressure. It takes a higher wind speed to get a particle moving. But now we’ll have the first opportunity to make detailed observations.”

Learning how dunes form on Mars today will help scientists study what processes shaped sandstones rock layers on the red planet, which are made from dunes that turned into rock long ago.

Curiosity is stopping at the dunes on its trek up Mount Sharp, exploring distinct layers on the way up the mountain to study different eras in Mars’ geologic past.

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Follow Stephen Clark on Twitter: @StephenClark1.

Source: Space Flight

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Curiosity rover reaches Martian sand dunes

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