INTEGRAL - A CHALLENGING SCIENTIFIC MISSION

The spectroscopic study of atomic and molecular lines in the infrared, optical and ultraviolet regions of the electromagnetic spectrum has p rovided us with knowledge and understanding of the physics of normal s tars. Spectral lines in the gamma-ray region are produced by new and d ifferent processes. These include radioactivity, nuclear excitation, e lectron - positron annihilation and radiation in the vicinity of magne tic fields. Gamma-ray lines are indicators of all these processes and have now been observed at astrophysical sites. They provide powerful d iagnostics for the high-energy processes occurring in some of the most violent and exotic objects in the Universe. The key features of the I ntegral satellite will allow us to study in great detail these, and ot her sites of key interest in today's astrophysical research, with high sensitivity combined with very good energy resolution and very good i maging capabilities (in order to avoid source confusion) using two mai n instruments, and 'imager' and a 'Spectrometer'.