Sand dunes, a common feature on the surface of Mars, can provide a record of recent and past changes. Some dunes near Mars polar areas have been observed to move recently due to carbon dioxide ice sublimation, but it has not been confirmed whether dunes are still active all over Mars. Winds contribute to dune movement on Earth, but wind tunnel and atmospheric computer simulations have suggested that strong winds would be rare in the current Martian atmosphere.
In a new study, Silvestro et al. observe recent dune movement in Mars' tropical regions, which are not affected by seasonal changes in carbon dioxide frost.
Focusing on the Arabia Terra and Meridiani region on Mars, the researchers analyze images from the High Resolution Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter as well as other sources of data. They measure migration rates of two groups of ripples in the sand in a dune field in Meridiani Planum and find that dunes advanced about 0.41 meter (1.31-3.28 feet) in a Martian year.
The study shows clear evidence that wind-driven dune activity occurs regularly on Mars today. This suggests that carbon dioxide ice sublimation is not necessary for Martian sand movement, as had previously been thought, and that wind tunnel measurements and computer simulations showing that strong winds are rare on Mars need to be reconsidered.
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More information: Active aeolian processes on Mars: A regional study in Arabia and Meridiani Terrae, Geophysical Research Letters, 2011. doi:10.1029/2011GL048955