The 5-210 μm spectral range is one of the richest windows of the electromagnetic spectrum emitted by astrophysical objects. It spans the wavelength range over which the largest proportion of the energy is emitted during the evolution of galaxies. With its mid infrared spectral resolution, SPICA will resolve the gas dynamics of protoplanetary disks in hundreds of stars and, from far infrared spectroscopy of the oxygen and water lines in the same disks, will reveal the fist indications of the chemistry vital to the emergency of life. Moreover, SPICA will allow us to observe water ice in all environments, and to fully explore its role on planetary formation and evolution, and the emergence of habitable planets. SPICA far infrared photometric sensitivity will allow us to detect the photospheres of stars out to many kiloparsecs, giving us a unique and unbiased insight in which types of stars, and at what stage of evolution, have either planets formed or in the process of formation.

SPICA is ideally suited to study star-formation hidden by dust absorption, by tracing the solid state features of dust further into the past than ever before. The combination of mid infrared and far infrared spectroscopy on SPICA will provide, for the first time, the capability to detect the cooling lines out to the peak of star formation activity in the history of the Universe (z~ 1-2) for a wide range of galaxy types. SPICA will enable the study of interstellar medium conditions in central outbursts, circumnuclear rings, disks, winds and halos in galaxies of the local Universe, as well as comprehensively in sources in the distant Universe. SPICA spectroscopic observations will be unique to address the AGN-Starburst connection at high redshifts (z>3). The field of view of the SPICA instruments will provide a considerable spatial multiplexing advantage both for mapping local, resolved, galaxies and to perform cosmological surveys. Photometrically, SPICA has the sensitivity to detect high-luminosity objects out to z>4 and Milky Way-type populations out to z~1.