Development of a Coherent Doppler Lidar for Precision Landing on Planetary Bodies

A coherent Doppler lidar has been developed by NASA for providing vector
velocity and altitude data to landing vehicles. Future robotic and manned missions to
planetary bodies demand precise ground-relative velocity and altitude data to execute
complex descent maneuvers for safe, soft and pinpoint landing at a pre-designated site.
Operating from over five kilometers altitude, this lidar provides velocity and range data
within a few cm/sec and a few meters precision, respectively, depending on the vehicle
dynamics. Two upcoming lunar landing missions will serve as the technology demonstration
for robotic and manned landing missions to the Moon, Mars, and other solar system
destinations. This paper describes the lidar design and its expected performance on landing
vehicles.