In a first part the paper reviews some of the major Spitzer legacy imaging
surveys to show the quantity of data available, and the subsequent need for
spectroscopic follow-up surveys on equivalent wide fields. They are
required for many science cases, as giant star forming regions, young
planetary nebulea, the Galactic Centre, nearby galaxies, distant galaxy
clusters. This capability of wide, integral field spectroscopy, missing in
all the existing and planned astronomical facilities, thus, appears among
the most pertinent choice for the future of astronomy at Dome C. For the
instrumental solution, a
flexibility in the choice of spectral resolution and spectral domain on a
broad infrared range is desirable to be able to undertake a large variety of study, on
extragalactic and galactic fields as well. This capability can be only offered by
an Imaging FTS. It fully benefits from the low thermal background
emission of Dome C, particularly in the 1.8 to 5.5 μm range, and reach
an optimum sensitivity by imaging emission lines. In a difficult site as
Dome C, a dedicated, medium-size telescope would be the most effective way
of exploiting such an instrument.