Search Publications
Modeling Cassini UVIS Interplanetary Hydrogen Lyα Observations from 1999 to 2017
Pryor, Wayne R.; Esposito, Larry W.; Gladstone, G. Randall +3 more
The Cassini Orbiter Ultraviolet Imaging Spectrograph (UVIS) obtained interplanetary hydrogen Lyα observations from 1999 to 2017, with mid-2004 to 2017 observations obtained from Saturn orbit. During its Saturn orbital phase, the spacecraft moved from mostly downwind and sidewind in the heliosphere to upwind. We analyze the full set of observations…
The Electric Field outward of Saturn's Main Rings
Krupp, N.; Roussos, E.; Paranicas, C. +5 more
Cassini data are consistent with a global electric field in Saturn's magnetosphere that points approximately antisunward. The inner radial extent of this field was initially established using Saturn orbit insertion data but measurements of ultrarelativistic electrons from that pass cast some doubt on whether the electric field reaches all the way …
Haze Seasonal Variations of Titan's Upper Atmosphere during the Cassini Mission
West, Robert A.; Vinatier, Sandrine; Seignovert, Benoît +1 more
This study presents a 13 yr survey of haze UV extinction profiles, monitoring the temporal evolution of the detached haze layer (DHL) in Titan's upper atmosphere (350-600 km). As reported by West et al. (GRL vol.38, L06204) at the equator, we show that the DHL was present at all latitudes below 55°N during the northern winter (2004-2009). Subseque…
A Rotating Azimuthally Distributed Auroral Current System on Saturn Revealed by the Cassini Spacecraft
Coates, A. J.; Krupp, N.; Dougherty, M. K. +14 more
Stunning aurorae are mainly produced when accelerated electrons travel along magnetic field lines to collide with the atmosphere. The motion of electrons often corresponds to the evolution of a magnetic field-aligned current system. In the terrestrial magnetosphere, the current system is formed at the night-side sector, and thus produces an aurora…
Heliospheric Maps from Cassini INCA Early in the Cruise to Saturn
Mitchell, D. G.; Krimigis, S.; Clark, G. +8 more
We present new energetic neutral atom (ENA) maps from the Ion and Neutral Camera (INCA) instrument on Cassini from the year 2000, prior to Cassini's encounter with Jupiter. These maps are the first produced for the year 2000 and are the only maps with comprehensive spatial coverage from the peak of solar cycle 23. These ENA maps span the energy ra…
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…