Mass Loss Processes in Titan's Upper Atmosphere
Johnson, R. E.; Sittler, E. C.; Smith, H. T.; Young, D. T.; Waite, J. H.; Michael, M.; Tucker, O. J.
Abstract
Although Titan's atmospheric column density is about ten times that of the Earth's, its measured 15N/14N ratio suggests that considerable escape has occurred or that Titan's original material had a ratio closer to that of cometary materials. A number of active escape processes have been proposed: thermal escape, chemical-induced escape, slow hydrodynamic escape, pick-up ion loss, ionospheric outflow and plasma-ion-induced atmospheric sputtering. These loss processes and relevant simulations are reviewed in light of recent Cassini data.