Typically, data will be released after a 6 month calibration and validation period. Click Here for more information on MGS data release and archiving plans. The first martian sand dunes were observed by the Mariner 9 spacecraft in 1972. Dunes typically contain granular fragments of rocks and minerals. Mars Global Surveyor has taken many images of martian dunes.
Some dunes appear to be inactive and covered with dust.
Other dunes, however, show all of the characteristics of fresh, active dunes. The most exciting examples have been found among the dunes in the martian north polar region. These were first seen by Mariner 9 as a rippled texture, and by Viking as definitive sand dunes. The first images also showed small dark spots along the bases of many of the dunes. The dark material was presumed to be the sediment that comprises the north polar dunes.