Marching sand dunes stir up Mars mystery

Sand grains stirred up by the winds of Mars are tossed higher and farther than those kicked up by winds on Earth, a new study finds. The results could help explain how dunes migrate across the Martian surface as well as what whips up dust storms that blow across the red planet.

Scientists first noticed dunes on the Martian surface in pictures taken by NASA's Mariner missions in the 1970s and have seen dust storms of all sizes spread across the planet — one major storm in 2005 was even visible through a simple backyard telescope. But these features have puzzled astronomers because Mars has almost no atmosphere and very weak winds that seem unlikely to be able to sculpt dunes or whip up storms.

To help solve this conundrum, a team of scientists recently conducted wind tunnel simulations of windblown sand grains under the conditions found on both Earth and Mars to figure out how the particles would behave on these planets with vastly different atmospheres. Their results are detailed in the April 28 issue of the journal Proceedings of the National Academy of Sciences. - msnbc