Mars' Reconnaissance Orbiter Catches Mysterious And Beautiful Blue Sand Dune

The Mars Reconnaissance Orbiter has discovered blue sand on the Red Planet, although a more accurate description might be "sand that is actually gray but appears blue due to an optical illusion." Confused? Read on.

As reports, back in January the Orbiter zoomed in on a particular patch of ground on the Martian surface where things didn't appear as they should to the eyes of its commanders back on Earth. In the image released today (it's not clear why NASA waited six months to release it), you can see why: the blue sand dune stands in sharp contrast to the more conventional sand dunes surrounding it.

The blue dune is in Mars' 147-mile wide Lyot Crater, which lies about 50 degrees north of the Martian equator. The larger surrounding dunes are technically referred to as "barchan dunes" - that is, dunes shaped by the wind, according to Fraser Coast Chronicle.

The sand isn't actually blue, however. If you saw it with your naked eye, says NASA, it would just appear gray, albeit a different shade of gray from the surrounding sand.

"This particular dune, appearing like turquoise blue in enhanced color, is made of finer material and/or has a different composition than the surrounding."
The photograph was taken using the Orbiter's HiRISE camera, which has a resolution equivalent to being able to zoom in on an object the size of a coffee table. That's impressive, considering that the Orbiter orbits between 150 miles and 196 miles above the surface.

Planetary Geologist Alfred McEwen, a member of the team that operates the camera, explains how the camera works.

"The images are given min-max stretches in each individual color image to increase contrast. The dunes are actually grey, but appear relatively blue after such a stretch because most of Mars is red."
The $720 million Mars Reconnaissance Orbiter was launched in August 2005 and made it to Martian orbit in March 2006. The goal of the mission is to, among other things, search for evidence of water - past or present - on the planet, and to scout out possible landing sites for future missions, including possible manned missions.

Meanwhile, down on the surface of Mars, another spacecraft, the Opportunity Rover, is not living its best life. That's because it's enveloped in a dust storm, according to the Orlando Sentinel - a dust storm that has now expanded to the entire planet. These things can last for months, and there's nothing Opportunity commanders can do except wait it out, and hope the craft survives.