Light scattering by dust particles in microgravity: polarization and brightness imaging with the new version of the PROGRA2 instrument

Abstract

A new version of the PROGRA2 instrument, dedicated to measuring the polarization phase function of various kinds of solid particles, allows obtaining maps of polarization and brightness with a spatial resolution of a few tens of micrometers. The measurements are conducted in microgravity during parabolic flights to ensure random distribution and orientation of the particles. The results of the first two sessions are presented. Comparison between measurements and Mie theory modeling for glass spheres shows that the instrument works well and that accurate results can be obtained even at small phase angles. Results for irregularly shaped particles are also presented.