Planets

Sandbox Selfie! Curiosity Plays in Mars Sand Dune

Sure, NASA's Mars rover Curiosity has seen sand before, but this dune is by far the biggest and the six-wheeled rover is making the most of it.

Sure, NASA's Mars rover Curiosity has seen sand before, but this dune is by far the biggest and the six-wheeled rover is making the most of it.

PHOTOS: Curiosity Plays in Sandy Martian Dunes

Seen here on sol 1,228 (Jan. 19) of its mission, Curiosity another another picturesque selfie, using its robotic arm-mounted Mars Hand Lens Imager (MAHLI). MAHLI snapped 57 high-resolution images that were then stitched together to create the composite we see here (the full-resolution version can be viewed on the NASA Jet Propulsion Laboratory photo release), incorporating the rover and the dark sands of "Namib Dune."

These selfies not only make for beautiful Mars portraits, they are used by mission scientists to check on the physical condition of the rover and keep track of wear and tear.

PHOTOS: The Mysteries Behind the Dunes of Mars

This dune is part of the "Bagnold Dune Field" that can be found along the northwestern slopes of Aeolis Mons - the 3.4 mile-high mountain informally known as "Mount Sharp," in the center of Gale Crater. These dunes are of particular interest to mission scientists as orbital observations have shown that this field is active; Mars winds continually shape the terrain, causing the dunes to slowly roll across the landscape at a tortoise-like pace of 1 meter per year.

To better understand the dune's material, Curiosity has been capturing microscopic images of the sand, revealing its grain's very terrestrial-looking shape. Also, the rover has scooped some samples for further analysis inside its on-board chemistry lab. Before doing so, however, the rover encountered a minor difficulty with its Collection and Handling for In-situ Martian Rock Analysis (CHIMRA) that is used to sort different sized grains of sandy material for analysis. An actuator in CHIMRA didn't function as expected during processing of a third scoop of material, leading mission engineers to investigate the problem.

ANALYSIS: Mapping Mars' Ripples Unveils Dune Mysteries

Despite the setback, samples of the dune have been delivered for analysis. In addition, Curiosity has been imaging the same location of the nearby dune repeatedly for the past 2 months in the hope of measuring the active dune's movement with the Martian wind.

For more information about Curiosity's dune study and the recent challenges it has faced, read the NASA news update.

This Jan. 19, 2016, self-portrait of NASA's Curiosity Mars rover shows the vehicle at "Namib Dune," where the rover's activities included scuffing into the dune with a wheel and scooping samples of sand for laboratory analysis.

Mars plays host to a huge number of dune fields -- regions where fine wind-blown material gets deposited to form arguably some of the most beautiful dunes that can be found on any planetary body in the solar system. Using the powerful High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA's Mars Reconnaissance Orbiter, planetary scientists have an orbital view on these features that aid our understanding of

aeolian (wind-formed) processes

and Martian geology. Here are some of our favorite Mars dunes as seen by HiRISE. Pictured here are shell-like "

barchan dunes

" in the ancient Noachis Terra region of Mars.

Special thanks to Ari Espinoza of the

HiRISE team at the University of Arizona

for helping to compile this list.

PHOTOS: The Weirdest Craters on Mars

Dunes of many shapes, sizes and formation processes can be found on the Red Planet. Shown here are elegant "

linear dunes

" with deposits of larger rocks and possibly ices in their troughs.

READ MORE: Sand Dunes Could Reveal Weather on Alien Worlds

These slug-like dark dunes are striking examples of "

dome dunes

" -- elliptical accumulations of fine material with no-slip surfaces. These domes contrast greatly with the often jagged appearance of barchan dunes. Found at the bottom of Proctor Crater, they are darker than the surrounding crater floor as they are composed of dark basaltic sand that was transported by the wind.

READ MORE: Slug-Like Dunes on Mars

Looking like a wind-blown silk sheet, this field of "star dunes" overlays a plain of small ripples, another aeolian feature. The ripples move more slowly across the bottom of Proctor Crater, so the large dune field will travel

over

the smaller ripples. Dunes are continuously evolving and moving with the wind, ensuring that the Martian surface is never static.

READ MORE: Bouncing Sands of Mars Blow in the Wind

These "transverse dunes" are undergoing seasonal changes. Likely entering Mars summer, this region of dunes is stained with pockets of subliming ices -- likely carbon dioxide. As the ices turn from solid to vapor, dune material slumps, revealing dark, sandy material underneath.

Resembling the mouths of a shoal of feeding fish, this is a group of barchan dunes in Mars' North Polar region. Barchan dunes betray the prevailing wind direction. In this case, the prevailing wind is traveling from bottom right to top left; the steep slope of material (plus dune "horns") point to the downwind direction. The HiRISE camera monitors barchans to see if they move between observing opportunities, thereby revealing their speed of motion across the Martian plains.

This is the same barchan dune field, zoomed out, a "swarm" of dunes covering the plains.

Not all barchan dunes "behave" and form neat "horny" shapes. They can become muddled and overlapping, creating "barchanoid dunes," as shown here.

This very fluid-looking collection of barchans is accompanied by a wind-blown ridge in the Hellespontus region of Mars but...

...only when zoomed out does the true nature of this fascinating region become clear. The prevailing wind is eroding the mesas (small hills) to the right of the image, carrying fine material downwind (from right to left), creating a startling pattern of barchans and a viscous-looking trail of sandy ridges across the plains.

The band Train sang about the "Drops of Jupiter" -- what about the "Drops of Mars"? Sure, they're not made of any kind of fluid, but they do make for incredibly-shaped dunes. These raindrop-shaped dunes are found in Copernicus Crater and are known to be rich in the mineral olivine, a mineral that formed during the wet history of Mars' evolution.

READ MORE: Mars' 'Raindrop' Sand Dunes Swarm

These craggy-looking dunes are old barchanoids eroding away through seasonal processes (sublimation of sub-surface ices) and the persistent Martian wind.

These linking barchan dunes are at the leading edge of a dune field -- grains of dust have been blown across a plain, deposited and left to accumulate in elongated arrow shapes.

Dome-shaped dunes and barchans seem to "reach out" and touch their downwind partners with slumped material.

Barchan dunes inside Arkhangelsky Crater in the southern hemisphere of Mars reveal a wind direction from top left to bottom right. Note the tracks of Martian dust devils over the dune slopes.

For more on the HiRISE camera,

see the HiRISE website

and

regularly updated Tumblr page

. For more on Mars dune definitions,

check out the USGS Mars Dunes site

.