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Measuring Topography
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Measuring Topography

October 27, 2009
NEAR Shoemaker's Laser Rangefinder measures heights on Eros' surface by determining the time short pulses of laser light take to travel from the spacecraft to the asteroid and back. The elevations of points on the surface of Eros are determined by subtracting the laser-derived distance between the spacecraft and the surface from the distance between the spacecraft and Eros' center of mass, as determined from radio tracking.

NEAR team members use this information to build detailed models of Eros' shape, which in turn help them understand the asteroid's collisional evolution and internal structure. The shape of Eros also provides a context for interpreting images and compositional information.

This image is a high-resolution digital terrain model of Eros near 0 degrees longitude, determined from a shape model derived from 5.6 million laser measurements. The black grid values correspond to latitude and longitude; the colors correspond to distances to the asteroid's center of mass, as noted (in kilometers) on the colored bar on the right. This shape model has a spatial resolution of about 500 meters. The model continues to improve in resolution and accuracy as NEAR scientists collect and analyze more laser data.