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This picture shows a small part of a HiRISE image taken over the southern flanks of the largest volcano in the Solar System, Olympus Mons. Olympus Mons towers more than 20 kilometers (65 thousand feet) above the surrounding plains. While scientists still are not certain when it last erupted, Olympus Mons is one of the youngest volcanoes on Mars. However, as this picture shows, its lava flows are covered by a thick deposit of wind blown dust. This mantle largely buries the lava, but some underlying features can still be discerned. The pair of parallel ridges running through the middle of the picture are the margins of a buried lava channel. This channel originally formed as a flow of molten lava that had its sides freeze as it advanced. When the eruption ended, the lava continued to flow out of the middle of the flow, leaving an empty channel with high walls. Dust has now filled the channel, but the tops of the channel margins poke through in a few places, as shown by the rocks rolling down onto the dust. The curving cliff at the bottom of the image is the margin of a dust covered impact crater. While the high resolution that the HiRISE camera delivers provides little new information on the lava flows, it does allow a better understanding of the nature of the dust cover and how it is being moved and sculpted by wind.
Image TRA_000838_1945 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on September 30, 2006. The complete image (shown at top), centered at 14.2 degrees latitude, 227.6 degrees East longitude. The range to the target site was 271 km (169 miles). At this distance the image scale is 54 cm/pixel (with 2 x 2 binning) so objects ~162 cm across are resolved. The image shown here has been map-projected to 50 cm/pixel and north is up. The image was taken at a local Mars time of 3:25 PM and the scene is illuminated from the west with a solar incidence angle of 49.2 degrees, thus the sun was about 40.8 degrees above the horizon. At a solar longitude of 114.1 degrees, the season on Mars is Northern Summer / Southern Winter. |