Experimental impact shock chemistry on planetary icy satellites

We present new experimental results on impact shock chemistry into icy satellites of the outer planets. Icy mixtures of pure water ice with CO2, Na2CO3, CH3OH, and CH3OH/(NH4)2SO4 at 77 K were ablated with a powerful pulsed laser—a new technique used to simulate shock processes which can occur during impacts. New products were identified by GC-MS and FTIR analyses after laser ablation. Our results show that hydrogen peroxide is formed in irradiated H2O/CO2 ices with a final concentration of 0.23%. CO and CH3OH were also detected as main products. The laser ablation of frozen H2O/Na2CO3 generates only CO and CO2 as destruction products from the salt. Pulsed irradiation of water ice containing methanol leads also to the formation of CO and CO2, generates methane and more complex molecules containing carbonyl groups like acetaldehyde, acetone, methyl formate, and a diether, dimethyl formal. The last three compounds are also produced when adding ammonium sulfate to H2O/CH3OH ice, but acetone is more abundant. The formation of two hydrocarbons, CH4 and C2H6 is observed as well as the production of three nitrogen compounds, nitrous oxide, hydrogen cyanide, and acetonitrile.