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The Mercury Laser Altimeter (MLA) is shown ranging to Mercury's surface from orbit. In this animation, yellow flashes represent near-infrared laser pulses that can reflect off terrain in shadow as well as in sunlight. Using about as much power as a flashlight, the MLA instrument can range eight times a second to targets at distances as far as that from Washington, D.C., to Ottawa, Canada (~800 km), St. Louis, Missouri, or Orlando, Florida (~1200 km). The laser pulse returns from the surface in less than one hundredth of a second. This time interval can be measured to a precision equivalent to a hand's breadth uncertainly in distance. Measurements are assembled from individual profiles to produce a terrain model such as the one shown here.
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 acquired 88,746 images and extensive other data sets. MESSENGER is now in a year-long extended mission, during which plans call for the acquisition of more than 80,000 additional images to support MESSENGER's science goals.
For information regarding the use of images, see the MESSENGER image use policy.