We propose to obtain infrared spectra with PHOT-S for about 30 stars
located behind the Taurus nearby dark cloud. For a handful of them which
are bright enough, we would also like to obtain SWS01 spectra. These
observations will provide an essential tool to trace the evolution of the
dust composition throughout the cloud and in particular when going from the
dense cores to the much less dense regions. The spectral range of PHOT-S
includes several signatures of ices such as H2O (3 micron), CO2 (4.27
micron), CO (4.67 micron), and silicates (9.7 micron). With SWS01, the CO2
(15.2 micron) and the 18 micron silicate bands can also be studied. These
data will allow to understand under which conditions can the most reactive
forms of ice survive at the surface of the rather stable silicate grains.