Theoretical models of the spectrophotometric properties of atmosphereless bodies surfaces in the Solar System

In space missions remote sensing represents one of the most powerful tools for the observations of planetary objects. It allows to infer physical and chemical properties both of surfaces and atmospheres by spectroscopic and photometric analysis. However data produced by remote sensing observations need to be interpreted by physical models which describe the interaction between light and observed media. In this work we have applied the Hapke's solution to the radiative transfer equation to data from the VIMS spectrometer onboard the Cassini spacecraft, orbiting in the Saturn's system. This allowed us to determine the spectrophotometric properties of the major icy moons. In particular the composition of Mimas, Tethys, Dione, Rhea and Enceladus has been investigated. For the two latter moons also photometric properties have been studied. It comes out that the surfaces of these satellites can be modeled with water ice particles (40-70 µm in size) e minimal amounts (generally < 1%) of organic contaminants, like tholins and amorphous carbon. A similar approach has been applied to the study of the Saturn’s rings (A, B, C and Cassini Division), whose spectral characteristics can be obtained with the same paradigm of composition. At the same time we have applied the Hapke's model to laboratory spectra of pyroxenes powders with well-known composition and physical properties. The aim of this study is to investigate the spectral and photometric output of these minerals to be compared with data from space missions. Moreover it was investigated how geometric and compositional effects can modify spectral signatures (for example the band depth). A further step of this investigation was the application of the Hapke's model to retrieve medium optical constants. The last part of this thesis concerns the development of an IDL routine to simulate light scattering in particulate media with a Montecarlo method. Preliminary results are reported.