Review of the heritage and evolution of cometary ices, from proto-Solar volatiles to salts

Abstract:

Comets are thought to be some of the most pristine remnants of the building blocks of the Solar System, whose composition could provide information on planets formation and evolution. Cometary ices may have partially inherited the composition of the proto-Solar environment, but these ices undergo some evolutions as comets orbit and approach the Sun. This presentation will review the heritage and evolution of cometary ices, from their residence in the Kuiper Belt/scattered disk or Oort Cloud to their perihelion. To what extent are cometary ices transformed by galactic or solar energetic particles and/or thermal heating? The latter process causes the sublimation of ices. In the case of comet 67P/Churyumov-Gerasimenko, the desiccated surface resulting from this sublimation contains semi-volatile ammonium salts possibly inherited and/or produced in the comet. These salts may increase the amount of nitrogen in comets, previously thought to be deficient in this element, with important implications on how nitrogen was incorporated from the proto-Solar environment to planetary systems.