This image is a map projection of an oblique view. At the time of Mariner 10's first Mercury flyby, the planet's prime meridian (line of zero-degree longitude) was about 10° on the night side of the planet and hence was not visible to the cameras. A small crater visible in a Mariner 10 high-resolution image was selected to define the 20° West line of longitude. The crater, shown at the tip of the arrow in the MESSENGER image above, is named "Hun Kal," which means 20 in an ancient Mayan language.
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 250-meter/pixel (820 feet/pixel) morphology base map or the 1-kilometer/pixel (0.6 miles/pixel) color base map. It is not possible to cover all of Mercury's surface at this high resolution during MESSENGER's one-year mission, but several areas of high scientific interest are generally 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, MDIS is scheduled to acquire more than 75,000 images in support of MESSENGER's science goals.
Date acquired: September 04, 2011 Image Mission Elapsed Time (MET): 223616660 Image ID: 716393 Instrument: Narrow Angle Camera (NAC) of the Mercury Dual Imaging System (MDIS) Center Latitude: -0.16° Center Longitude: 340.7° E Resolution: 82 meters/pixel Scale: The crater above Hun Kal is about 19 km (12 mi.) in diameter. Incidence Angle: 18.9° Emission Angle: 66.3° Phase Angle: 82.5° Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington. More images