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Craters, lava and tectonics scooped by Mars Express DR EMILY BALDWIN ASTRONOMY NOW Posted: July 27, 2009 
ESA's Mars Express High Resolution Stereo Camera has scooped impact craters, ancient lava flows and evidence of tectonic activity all near Ma'adim Vallis, one of the largest canyons on Mars. 
Mars Express viewed the region close to Ma'adim Vallis, scooping impact craters and evidence for volcanic and tectonic activity. The pictures are centred at about 29°S and 182°E and have a ground resolution of 15 m/pixel. Image:ESA/DLR/FU Berlin (G. Neukum).
Ma'adim Vallis is situated between two of the Solar System's largest geologic features: the volcanic region of Tharsis, which hosts Olympus Mons at three times the height of Mount Everest, and the Hellas Planitia impact basin. The canyon itself is 20 kilometres wide and up to two kilometres deep, originating near the southern highlands where the Martian crust is divided into a striking dichotomy between the cratered highlands and the smooth lowland plains. Last year, researchers suggested that the entire lowland plains were a result of a massive impact event (read the news report describing this research here). The new Ma'adim Vallis regional images were captured on Christmas Eve 2008. They cover an area 138 by 70 kilometres – roughly the size of Cyprus – and have a resolution of 15 metres per pixel. 
Zoomed in image showing a sharp divide in dark lava and lighter material (box 1), a 20km wide crater (box 2) and a long trough that runs through the entire image (box 3). Image: ESA/DLR/FU Berlin (G. Neukum).
The image provides clear evidence of the red planet's active past. Splitting the image in two is a trough running for over 200 kilometres. It likely formed when the nearby Tharsis region bulged up when it was volcanically active, creating stress in the crust which was released as cracks and deep fractures. A boundary between light and dark material is visible to the left of the trough, which is likely the edge of a lava flow. Compressional features known as wrinkle ridges were formed as the cooling lava contracted, buckling up into sinuous ridges. Wrinkle ridges are also common on the lunar maria. 
Perspective view of the Ma'adim Vallis regional area. Image: ESA/DLR/FU Berlin (G. Neukum).
The terrain has also been modified through impact events. The largest crater in the image is some 20 kilometres wide and hosts several smaller craters, the largest of which, at seven kilometres wide, sits on the southern rim of the crater and is surrounded by a prominent blanket of material excavated during the impact event. The main crater is partially filled with lava, showing that it must have formed before the lava set in. Mars Express has been orbiting the red planet for seven and a half years. |
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