Search Publications
Measurement and implications of Saturn's gravity field and ring mass
Iess, L.; Tortora, P.; Zannoni, M. +10 more
The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with …
Close Cassini flybys of Saturn's ring moons Pan, Daphnis, Atlas, Pandora, and Epimetheus
Brown, R. H.; Baines, K. H.; Buratti, B. J. +35 more
Saturn's main ring system is associated with a set of small moons that either are embedded within it or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the ring-grazing orbits of the Cassini mission. …
Close-range remote sensing of Saturn's rings during Cassini's ring-grazing orbits and Grand Finale
Nicholson, Philip D.; Hedman, Matthew M.; Sotin, Christophe +22 more
Saturn's rings are an accessible exemplar of an astrophysical disk, tracing the Saturn system's dynamical processes and history. We present close-range remote-sensing observations of the main rings from the Cassini spacecraft. We find detailed sculpting of the rings by embedded masses, and banded texture belts throughout the rings. Saturn-orbiting…
Saturn's magnetic field revealed by the Cassini Grand Finale
Cao, Hao; Dougherty, Michele K.; Hunt, Gregory J. +10 more
During 2017, the Cassini fluxgate magnetometer made in situ measurements of Saturn's magnetic field at distances ~2550 ± 1290 kilometers above the 1-bar surface during 22 highly inclined Grand Finale orbits. These observations refine the extreme axisymmetry of Saturn's internal magnetic field and show displacement of the magnetic equator northward…
Chemical interactions between Saturn's atmosphere and its rings
Kurth, W. S.; Mitchell, D. G.; Wahlund, J. -E. +25 more
The Pioneer and Voyager spacecraft made close-up measurements of Saturn's ionosphere and upper atmosphere in the 1970s and 1980s that suggested a chemical interaction between the rings and atmosphere. Exploring this interaction provides information on ring composition and the influence on Saturn's atmosphere from infalling material. The Cassini Io…
In situ collection of dust grains falling from Saturn's rings into its atmosphere
Postberg, Frank; Schmidt, Jürgen; Spahn, Frank +16 more
Saturn's main rings are composed of >95% water ice, and the nature of the remaining few percent has remained unclear. The Cassini spacecraft's traversals between Saturn and its innermost D ring allowed its cosmic dust analyzer (CDA) to collect material released from the main rings and to characterize the ring material infall into Saturn. We rep…
In situ measurements of Saturn’s ionosphere show that it is dynamic and interacts with the rings
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +10 more
The ionized upper layer of Saturn’s atmosphere, its ionosphere, provides a closure of currents mediated by the magnetic field to other electrically charged regions (for example, rings) and hosts ion-molecule chemistry. In 2017, the Cassini spacecraft passed inside the planet’s rings, allowing in situ measurements of the ionosphere. The Radio and P…
Dust grains fall from Saturn's D-ring into its equatorial upper atmosphere
Persoon, A. M.; Kurth, W. S.; Mitchell, D. G. +12 more
The sizes of Saturn's ring particles range from meters (boulders) to nanometers (dust). Determination of the rings' ages depends on loss processes, including the transport of dust into Saturn's atmosphere. During the Grand Finale orbits of the Cassini spacecraft, its instruments measured tiny dust grains that compose the innermost D-ring of Saturn…
A radiation belt of energetic protons located between Saturn and its rings
Livi, S.; Krupp, N.; Jones, G. H. +21 more
Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable radiation belts exist near the planet and inward of the rings was previously unknown. The Cassini spacecraft's Magnetosphere Imaging Instrument obtained measurements of a …
Flux and composition of interstellar dust at Saturn from Cassini’s Cosmic Dust Analyzer
Kempf, S.; Postberg, F.; Srama, R. +12 more
Interstellar dust (ISD) is the condensed phase of the interstellar medium. In situ data from the Cosmic Dust Analyzer on board the Cassini spacecraft reveal that the Saturnian system is passed by ISD grains from our immediate interstellar neighborhood, the local interstellar cloud. We determine the mass distribution of 36 interstellar grains, thei…