Synergism of Saturn, Enceladus and Titan and Formation of HCNO Exobiological Molecules

Saturn as a system has two very exotic moons Titan and Enceladus. Titan with energy input from Saturn's magnetosphere, solar UV irradiation, and galactic cosmic rays (GCRs) can make HCN based molecules. Space radiation effects at both moons, and as coupled by the Saturn magnetosphere, could lead to the evolution of biological models at Titan composed of HCNO with oxygen as the new ingredient. The "Old Faithful" model by Cooper et al. (2009) suggests that Enceladus, highly irradiated by Saturn magnetospheric electrons, has episodic ejections of water vapor into Saturn's magnetosphere. At Titan Cassini discovered keV oxygen ions, evidently from Enceladus, bombarding Titan's upper atmosphere (Hartle et al., 2006a,b) and abundant heavy positive and negative ions within Titan's upper atmosphere (Coates et al., 2007). Heavy ion formation in Titan's upper atmosphere can be due polymerization of aromatics such as Benzenes to make polycyclic aromatic hydrocarbons (PAH) (Waite et al., 2007) and/or the polymerization of carbon chains from acetylene to make fullerenes (Sittler et al., 2009). Fullerenes, which are hollow carbon shells, can trap the keV oxygen ions. Clustering of fullerenes, PAHs and PAHNs can form larger aerosols enriched in trapped oxygen which can then precipitate down to Titan's surface. GCRs will chemically process aerosol materials at the surface and provide sufficient energy for processing them into more complex organic forms such as amino acids. We have developed an advanced model of GCR interaction with Titan's atmosphere, surface and sub-surface. This allows one to estimate dose rates at the surface and below and then using laboratory results by Hudson et al. (2008) to estimate abundances of the amino acid such glycene to ~ 100 ppb over time periods relatively short compared to solar system timescales. Therefore, the Saturn system can provide pathways for the accumulation of prebiotic chemicals on Titan's surface.