Search Publications
Cassini Ring Seismology as a Probe of Saturn’s Interior. I. Rigid Rotation
Fortney, Jonathan J.; Marley, Mark S.; Mankovich, Christopher +1 more
Seismology of the gas giants holds the potential to resolve long-standing questions about their internal structure and rotation state. We construct a family of Saturn interior models constrained by the gravity field and compute their adiabatic mode eigenfrequencies and corresponding Lindblad and vertical resonances in Saturn’s C ring, where more t…
Titan Surface Temperatures during the Cassini Mission
Flasar, F. M.; Coustenis, A.; Achterberg, R. K. +11 more
By the close of the Cassini mission in 2017 the Composite Infrared Spectrometer had recorded surface brightness temperatures on Titan for 13 yr (almost half a Titan year). We mapped temperatures in latitude from pole to pole in seven time segments from northern mid-winter to northern summer solstice. At the beginning of the mission the warmest tem…
Nitrogen-containing Anions and Tholin Growth in Titan’s Ionosphere: Implications for Cassini CAPS-ELS Observations
Coates, Andrew J.; Carrasco, Nathalie; Desai, Ravindra T. +4 more
The Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) instrument on board Cassini revealed an unexpected abundance of negative ions above 950 km in Titan’s ionosphere. In situ measurements indicated the presence of negatively charged particles with mass-over-charge ratios up to 13,800 u/q. At present, only a handful of anions have bee…
Auroral Beads at Saturn and the Driving Mechanism: Cassini Proximal Orbits
Roussos, E.; Badman, S. V.; Bonfond, B. +9 more
During the Grand Finale Phase of Cassini, the Ultraviolet Imaging Spectrograph on board the spacecraft detected repeated detached small-scale auroral structures. We describe these structures as auroral beads, a term introduced in the terrestrial aurora. Those on DOY 232 2017 are observed to extend over a large range of local times, i.e., from 20 L…
Jovian Cosmic-Ray Protons in the Heliosphere: Constraints by Cassini Observations
Krupp, Norbert; Krimigis, Stamatios M.; Mitchell, Donald G. +5 more
Measurements of >82 MeV Galactic cosmic-ray (GCR) protons at Earth indicate that they may be mixed with protons that leak into the heliosphere from Jupiter’s magnetosphere (Jovian cosmic-ray protons (JCRPs)). A ∼400 day periodicity in these proton fluxes, which is similar to the synodic period between Jupiter and Earth, and an excess proton flu…
Long-standing Small-scale Reconnection Processes at Saturn Revealed by Cassini
Coates, A. J.; Krupp, N.; Dougherty, M. K. +12 more
The internal mass source from the icy moon Enceladus in Saturn’s rapidly rotating magnetosphere drives electromagnetic dynamics in multiple spatial and temporal scales. The distribution and circulation of the internal plasma and associated energy are thus crucial in understanding Saturn’s magnetospheric environment. Magnetic reconnection is one of…
Estimates of the Atmospheric Escape Rates of CH4 from Titan
Ip, Wing-Huen; Hsu, Jen-Kai
The upper atmosphere of Titan is highly variable as characterized by the variations of the thermospheric and exospheric temperatures from in situ measurements by Cassini at different Titan encounters. A related question has to do with the escape flux of CH4 that might also change with the complex plasma environment and ionospheric condi…