MESSENGER Laser Altimeter (VIDEO) NASA/Goddard Space Flight Center This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption MESSENGER's Mercury Laser Altimeter sends out laser pulses that hit the ground and return to the instrument. The amount of light that returns for each pulse gives the reflectance at that point on the surface. The amount of time it takes the pulse to make its trip indicates how far away that point on the surface is, allowing the topography to be mapped. Credit NASA/Goddard Space Flight Center Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.