Vegetation Canopy Lidar Mission Page 2 A New Application of Lidar Technology Lidar, or laser altimetry, is an emerging remote-sensing technology already used in Earth and planetary science applications. Laser altimeters were used in the early 1970's on three Apollo missions. Only in the last decade have technological advances resulted in the development of reliable and accurate spaceborne sensors. These include the Mars Observer Laser Altimeter and the Shuttle Laser Altimeter.
Lidars send a short pulse of light energy from a laser at a target.
The time it takes for each pulse to complete a roundtrip to and from the target is converted into a direct measure of the elevation of the target. Lidar sensors measure elevation by bouncing laser light off of a surface and measuring the time the light pulse takes to return. The above diagram shows how the Vegetation Canopy Lidar measures forest height by detecting reflected laser light. The VCL lidar holds five lasers that each send 242 pulses per second at the Earth's surface. Each beam covers an area 75 feet across.