FAST-TRAVELING SAND DUNES INDICATE THE RED PLANET'S SURFACE IS MORE ACTIVE THAN PREVIOUSLY THOUGHT.

Mars has an atmosphere 100 times less dense than Earth's, scientists figured hurricane-force winds are needed to move sand around in the thin Martian air, and winds that high are rare.


But this turns out to be only half the story.


New analysis of high-resolution images, taken by NASA's Mars Reconnaissance Orbiter, show sand dunes in an area known as Nili Patera are shifting as fast as some dunes on Earth -- despite a dearth of high-speed winds.


Scientists suspect it takes a big wind to get sand particles airborne, but once launched from the surface, they bounce around with ease, thanks to the planet's thin atmosphere and low gravity.