Investigation of diurnal variability of water vapor in Enceladus' plume by the Cassini ultraviolet imaging spectrograph
Hansen, C. J.; Hendrix, A. R.; Portyankina, G.; Aye, K. -M.; Colwell, J. E.; Esposito, L. W.; Shemansky, D.
United States
Abstract
An occultation of ɛ Orionis by Enceladus' plume was observed with Enceladus at an orbital longitude near apoapsis in order to investigate whether water vapor flow is modulated diurnally, similar to ice particles. The occultation showed that the bulk water vapor emanating from Enceladus changes little with orbital position. The amount of gas in at least one supersonic jet increased significantly, implying that the increase in the number of particles lofted at apoapsis could be due to more gas coming from the supersonic jets and not the overall gas flux from the tiger stripe fissures that cross Enceladus' south polar region.