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Chain Reaction
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Chain Reaction

November 27, 2012
Date acquired: October 07, 2012 Image Mission Elapsed Time (MET): 258083386 Image ID: 2719301 Instrument: Wide Angle Camera (WAC) of the Mercury Dual Imaging System (MDIS) WAC filter: 7 (748 nanometers) Center Latitude: 66.31° Center Longitude: 356.2° E Resolution: 162 meters/pixel Scale: This image is about 83 km (51.5 miles) across. Incidence Angle: 87.3° Emission Angle: 3.7° Phase Angle: 91.0° Of Interest: This image, taken with the Wide Angle Camera (WAC), shows several secondary crater chains. These features are formed when ejecta from a primary impact is thrown outward. As the pieces fall back to the surface, they can form chains of small secondary craters. In this particular case, the primary impact was most likely the one that formed Abedin crater. With the Sun just 3° above the horizon (incidence angle = 87°), the craters are filled with shadow. This image was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map is a major mapping activity in MESSENGER's extended mission and complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map is being acquired with an average resolution of 200 meters/pixel. The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing. During the one-year primary mission, MESSENGER acquired 88,746 images and extensive other data sets. MESSENGER is now in a yearlong extended mission, during which plans call for the acquisition of more than 80,000 additional images to support MESSENGER's science goals. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington


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