Space missions have shown that among the most abundant elements in the Universe, three of them, hydrogen, oxygen and nitrogen, present isotopic enrichments (abundances larger than those of the Solar nebula) in comets, carbonaceous chondrites, and other pristine small Solar System bodies. ... Fractionation in solar system bodies . ... Maite BeltrУЕn, INAF-Osservatorio di Arcetri (co-chair) . Francesco Fontani, INAF-Osservatorio di Arcetri (co-chair) . ... Home . ...