Characterization of particles from stratospheric launch vehicle plumes using wavelength-dependent Lidar techniques

Our Mobile Lidar Trailer (MLT) has been deployed to Cape Canaveral Air Stat ion for the purpose of studying the characteristics of launch vehicle plume s in the stratosphere. In addition to measurements of plume extent and disp ersion rates, information on particle species and size can be obtained from the wavelength dependence of the Mie return signal. We measure the backsca ttering ratio of Mie to Rayleigh return at several wavelengths and compare the results to a model of Mie scattering cross sections for homogeneous sph eres of specific refraction index and radius. Of primary interest are the c alculations for particles which are present in the exhaust of solid rocket motors (SRM) and are conjectured to be instrumental in the catalysis of hal ogenic destruction of stratospheric ozone. Our data indicate that these par ticles, at least within the first half-hour after launch, are small (r < 50 nm as an upper limit). The data also shows a trend of the mean particle ra dius increasing with time.