  Topic of this work are comets, small and elusive objects that may hold great
secrets about the origin of the Solar System and life on Earth, being among the
most primitive objects. The method of investigation addressed in this work is
the visible and infrared spectrophotometry by imaging spectrometers, designed
for the observation of remote planetary atmospheres and surfaces, capable to
acquire hyperspectral data with high spatial and spectral resolution. The
context under which this mission moves its steps is described in the first
chapter. In the second chapter the performances of the VIRTS instrument,
onboard Rosetta spacecraft, are analyzed in detail. In particular the modeling
of the signal to noise ratio is the main argument of this chapter. The third
chapter shows simulations of possible spectra of the comet's nucleus, which are
useful for both a comparison with real spectra, and for a planning of the
observations. Hapke's radiative transfer model is used to invert acquired data
to infer physical properties. The fourth chapter introduces a method for
spectral modeling. It includes the information on the instrumental noise,
permitting the analysis of the goodness of the models, and an estimation of the
error of the retrieved parameters. The fifth chapter presents the spectral
analysis of Tempel 1 and Hartley 2 whose data are coming from Deep Impact space
mission and its extended investigation. The sixth chapter shows the photometric
analysis of Lutetia asteroid, which was encountered by Rosetta during its
cruise phase. This work have paved the way to the analysis of the final target
of Rosetta: comet 67P/Churyumov-Gerasimenko. The tools presented are currently
used by the VIRTIS Team to produce works on the comet, that are recommended to
the reader. Since a complete analysis on the comet is outside the scope of this
work, just preliminary results are shown here.
