Airborne and Spaceborne Lidar

The evolution of lidar, from those early ground-based measurements to our first long-duration spaceborne experiments, is schematically represented in Fig. 13.1. It depicts the first lidars in the 1960s as ground-based, followed by systems first flown in 1969 on small aircraft, and followed in the late 1970s by lidars flown on large aircraft capable of long-range measurements. Starting in 1979, flights aboard high-altitude aircraft were accomplished where data were taken at approximately 20 km altitude. The depiction finishes with the first spaceborne lidar using Shuttle for the 11-day flight of LITE, the Lidar In-space Technology Experiment in 1994, and finally, the first long-duration spaceborne low-Earth-orbit flight, that of the Geoscience Laser Altimeter System (GLAS) launched aboard ICESat in January 2003. The above were pathfinders in lidar’s evolution, with the first flights utilizing elastic backscatter for cloud and aerosol measurements. This chapter will describe the airborne and spaceborne firsts, including flights of lidars using other techniques like DIAL, and then present a more detailed description of specific examples of both airborne and spaceborne missions. It will conclude with a look into the future. It will not cover in any detail airborne or spaceborne laser altimeters, bathymeters or Doppler lidars.