<title>Coherent launch-site atmospheric wind sounder</title>

Abstract

The coherent launch-site atmospheric wind sounder (CLAWS) is a lidar atmospheric wind sensor designed to measure the winds aloft at space launch facilities to an altitude of 20 km. Candidate lidar systems analyzed for use in CLAWS include Nd:YAG, Ho:YAG, and CO2. Detailed simulations were carried out by Coherent Technologies, Inc. The results of our development studies include: (1) definition of lidar sensor requirements, (2) definition of a system to meet those requirements, and (3) a concept evaluation with recommendations for the most feasible and cost-effective lidar system for use as an input to a guidance and control system for a missile or spacecraft launch. A field test program will begin in August 1991, in which the ability of CLAWS to meet NASA goals for increased safety and launch/mission flexibility at Kennedy Space Center (KSC) will be evaluated with regard to maximum detection range, refractive turbulence, and aerosol backscattering efficiency at the three lidar wavelengths. It is found that the shorter wavelength solid-state lasers will afford better performance (longer detection range), are more energy efficient, and are more compact for operation in the humid, postvolcanic aerosol environment found at KSC. Finally, the Ho:YAG (2.1 micrometers ) lidar gives the best performance at an eyesafe wavelength and would be applicable for detecting winds aloft during descent as well as during ascent.