Mars continues to show itself active, at least as far as dunes are concerned. A new study published in Geophysical Research Letters (October 22, 2011) by a group of scientists led by Simone Silvestro (SETI Institute) reports on dune movements in Arabia and Meridiani recorded between 2007 and 2010. The team used images from the Viking mission and THEMIS daytime infrared observations for a base map, and identified changes using the HiRISE camera.
SANDS OF ARABY. A Viking color mosaic shows the areas of dune motion studies in Arabia and northern Meridiani. At the Arabia 4 site (lower right), the team detected two lee dunes merging, a first for Mars. (Image is Figure 1a from the paper.)
They found six sites with clear signs of modifications due to wind over the course of a Martian year. One of their study sites, Arabia 4 (see image at right), offered the first known Martian example of lee dunes merging. In their Meridiani study areas, only one showed signs of change. Work by others has already located moving dunes in Endeavour Crater, currently the exploration target of the Mars rover Opportunity (See “Will Opportunity find dunes on the move?“)
The team concludes that, “Dune advancement may be common throughout the Martian tropics.”