Saturn's inner satellites: Ice chemistry and magnetosphere effects

[1] The magnetosphere of Saturn contains plasma ions that corotate with the magnetic field of the planet and impact the satellites, changing the chemical nature of their surfaces. The Voyager spacecraft observed ionic species such as O+,H2O+,N+,N-2(+),H+, and others, as well as electrons. If N+ and N-2(+) ions from Titan reach the inner satellites Rhea, Dione, Tethys, Enceladus, and Mimas, implanting of these ions into their water-ice surfaces should induce a complex nitrogen oxides chemistry. Species observed in laboratory experiments of N+ impact into water ice include NO, N2O, NO2,NO3, HNO2, HNO3,NH2OH, HNO, NH, and NH2. Impact of N-2(+) may yield N2O, HNNO, and N-2. If the surfaces also contain CO2, then other species produced as a result of N+ impact into H2O/ CO2 ice may be HNCO, NCO, and R-OCN. Once HNCO (with its C-N bond) is formed, then production of amino acids may occur. Chemical schemes show that successive reaction of HNCO with H and CO could lead to the smallest amino acid, glycine, in only five steps. Energy fluxes for ions, electrons, and photons are summed for each satellite. Column densities of the nitrogen-containing species are calculated. The simplest molecule, NO, should have an appreciable vapor pressure at Saturnian satellite temperatures. At 90 K, the vapor pressure of NO is similar to4 mbar. At 105 K, its vapor pressure is 98 mbar. These gases may form transient atmospheres on the satellites. This should be observable with high-resolution instruments.