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The Details of a Ray
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The Details of a Ray

November 2, 2012
Date acquired: August 30, 2012 Image Mission Elapsed Time (MET): 254798310 Image ID: 2485907 Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) Center Latitude: 28.45° Center Longitude: 67.70° E Resolution: 34 meters/pixel Scale: This image is approximately 35 km (22 mi.) across Incidence Angle: 69.9° Emission Angle: 2.7° Phase Angle: 72.5° Of Interest: What could have caused this small, bright swarm of impact craters? The fact that they are fairly similar in size and clustered together suggests that they are secondary craters, which form when material from a larger primary crater is ejected and impacts the surrounding terrain. The high albedo and sharp rims and walls of these small craters also suggest they formed relatively recently, though no large fresh craters are seen in the immediate surroundings. Instead, they appear to originate from Fonteyn crater, just over 1,000 km (622 mi.) to the east. This small, bright patch is a segment of one of Fonteyn's beautiful rays, and shows just how important a process secondary cratering is on Mercury, such that even craters around 29 km (18 mi.) in diameter can affect the surface great distances away. This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. 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