Submitted by Subeditor on Tue, 2015-12-01 13:47 London: An illusion created by sand dunes has made Mars look like its covered in forests.Groups of dark brown streaks have been photographed by the Mars Reconnaissance Orbiter on melting pinkish sand dunes covered with light frost. When these image were taken, dark sand on the interior of Martian sand dunes became visible as the spring sun melted the lighter carbon dioxide ice that rested on the top.When this happens near the top of a dune, dark sand may cascade down the dune leaving dark surface streaks.The streaks might appear at first to be trees standing in front of the lighter regions, but they have no shadows. The image was taken in 2008 and objects about 25cm across are resolved on this image spanning about 0.6 miles (1km).Close ups of some parts of this image show billowing plumes indicating that the sand slides were occurring even while the image was being taken. In another image, Mars' northern-most sand dunes are beginning to emerge from their winter cover of seasonal carbon dioxide ice. Dark, bare south-facing slopes are soaking up the warmth of the sun.The steep sides of the dunes are also ice-free along the crest, allowing sand to slide down the dune.Dark splotches are places where ice cracked earlier in spring, releasing sand. Soon the dunes will be completely bare and all signs of spring activity will be gone.The Mars Curiosity rover is attempting to understand more about active sand dune behaviour in its latest mission. Over the past week, Curiosity has been sending back fresh images of their dark, rippled surface The images marks the first time active sand dunes have been investigated on another planet.Nasa hopes the images will answer questions about how dunes and wind interact in a low-gravity environment.Beyond imagination, Forests on Mars !!??? 'These dunes have a different texture from dunes on Earth,' said Nathan Bridges of Johns Hopkins University — who co-heads Curiosity's 'dune campaign'. 'The ripples on them are much larger than ripples on top of dunes on Earth, and we don't know why.''We have models based on the lower air pressure. It takes a higher wind speed to get a particle moving. 'But now we'll have the first opportunity to make detailed observations.'