Energetic materials are sensitive to "low" mechanical, chemical and thermal stresses, whose origin is probably linked to their microstructural damaging. The present study focuses on a composite propellant composed of ammonium perchlorate grains in a polyurethane binder (HTPB). To describe the thermo-mechanical behavior of this material, at the mesoscopic scale under low impact, drop weight tests are carried out under various experimental configurations, adding a high speed camera recorder and ante- and post-mortem X-ray microtomographies. Several modifications of the usual device are developed in order to explore as many experimental configurations as possible. Results obtained during validation tests of the modified device enable us to consider that it can give the required data for the identification and characterization of the damage mechanisms that could be part of the hot spots initiation process and reaction ignition under low impact.