PRIMA promise of deciphering interstellar dust evolution with observations of the nearby Universe

We develop a few science cases, using the PRIMA far-infrared (FIR) probe, aimed at achieving several breakthroughs in our understanding of the dust properties and their evolution. We argue that the specific observational capabilities of PRIMA, namely, its unprecedented sensitivity over the whole FIR range and the possibility to obtain continuous spectra between λ ¼ 24 and 235 μm, are essential to progress in our understanding of the physics of the interstellar medium (ISM) and galaxy evolution. Our science cases revolve around observations of nearby galaxies. We discuss the importance of detecting the IR emission of the diffuse ISM of these galaxies, including very low-metallicity systems. We also discuss the opportunity of detecting various solid-state features to understand the mineralogy of interstellar grains. Finally, we stress the unique opportunity brought by the possible simultaneous measures of both the dust continuum and the FIR fine-structure gas lines. These science cases could be distributed in a few large programs.