The Airborne Topographic Mapper (ATM) is a scanning LIDAR developed and used by NASA for observing the Earth’s topography for several scientific applications, foremost of which is the measurement of changing arctic and antarctic icecaps and glaciers. It typically flies on aircraft at an altitude between 400 and 800 meters above ground level, and measures topography to an accuracy of better than 10 centimeters by incorporating measurements from GPS (global positioning system) receivers and inertial navigation system (INS) attitude sensors.

This instrument is now retired but historical data can be found here at NSIDC