The ASTRA project aims to reconstruct the sound or timbre of ancient instruments (not existing anymore) using archaeological data as fragments from excavations, written descriptions, pictures, etc. The technique used is the Physical Modeling Synthesis, a complex digital audio rendering technique which allows modeling the time-domain physics of the instrument. In other words the basic idea is to recreate a model of the musical instrument and produce the sound by simulating its behavior as a mechanical system. The application would produce one or more sounds corresponding to different configurations of the instrument (i.e. the different notes). The project runs since 2006 thanks to the GEANT backbone and to computing resources located in Europe and in other regions of the world, allowing researchers, musicians and historians to collaborate, communicate and share experiencies on lost instruments and sounds ASTRA brings again to life.