The great success of the two SIR-C/X-SAR missions and the lack of global topographic data are the reasons at the basis of third Shuttle Radar Topographic Mission(SRTM). The mission is a joint program among NASA, NIMA, DLR and the Italian Space Agency. The SRTM mission aim is to create a tri-dimensional topographic map of the Earths surface 30 times as precise as the best global maps in use today.