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How MLA Works

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.

Date acquired: November 29, 2012

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington