  In the laboratory, the photo-and thermochemical evolution of ices, made of
simple molecules of astrophysical relevance, always leads to the formation of
semi-refractory water-soluble organic residues. Targeted searches for specific
molecules do reveal the notable presence of two families of important molecular
''bricks of life'': amino acids, key molecules in metabolism, and sugars,
including ribose, the backbone of RNA molecules which support the genetic
information in all living entities. Most of these molecules are indeed found in
primitive carbonaceous meteorites and their implication in prebiotic chemistry
at the surface of the early Earth must be seriously considered. These molecules
are, almost all, chiral. In meteorites, some amino acids do show significant
enantiomeric excesses, practically exclusively of the L-form. In our
experiments, we investigate the role of circularly polarized light obtained
from the DESIRS beamline of the synchrotron SOLEIL, a light commonly observed
in regions of star formation, in order to generate an initial symmetry breaking
in chiral amino acids produced and then indeed detected in our samples. We
present first a brief global description of the chemical evolution of the
Galaxy. Then, using our laboratory simulations, we suggest the importance of
cosmic ices in the build-up of complex organic matter, including
enantioenrichment at the surface of telluric planets like the Earth, thus
establishing a link between astrochemistry and astrobiology.
