The dart and associated launching system was developed by engineers at MSFC to collect a sample of the aluminum oxide particles during the static fire testing of the Shuttle's solid rocket motor. The dart is launched through the exhaust and recovered post test. The particles are collected on sticky copper tapes affixed to a cylindrical shaft in the dart. A protective sleeve draws over the tape after the sample is collected to prevent contamination. The sample is analyzed under a scarning electron microscope under high magnification and a particle size distribution is determined. This size distribution is input into the analytical model to predict the radiative heating rates from the motor exhaust. Good prediction models are essential to optimizing the development of the thermal protection system for the Shuttle.