Search Publications
New constraints on Saturn's interior from Cassini astrometric data
Thuillot, William; Pascu, Dan; Guillot, Tristan +15 more
Using astrometric observations spanning more than a century and including a large set of Cassini data, we determine Saturn's tidal parameters through their current effects on the orbits of the eight main and four coorbital Moons. We have used the latter to make the first determination of Saturn's Love number from observations, k2=0.390 …
True polar wander of Enceladus from topographic data
Hedman, Matthew M.; Schenk, Paul M.; Burns, Joseph A. +4 more
Many objects in the solar system are suspected to have experienced reorientation of their spin axes. As their rotation rates are slow and their shapes are nearly spherical, the formation of mass anomalies, by either endogenic or exogenic processes, can change objects' moments of inertia. Therefore, the objects reorient to align their largest momen…
Impact crater relaxation on Dione and Tethys and relation to past heat flow
Schenk, Paul M.; White, Oliver L.; Bray, Veronica J. +3 more
Relating relaxation of impact crater topography to past heat flow through the crusts of icy satellites is a technique that has been applied to satellites around Jupiter and Saturn. We use global digital elevation models of the surfaces of Dione and Tethys generated from Cassini data to obtain crater depth/diameter (d/D) data. Relaxation is found t…
Exposure age of Saturn's A and B rings, and the Cassini Division as suggested by their non-icy material content
Nicholson, P. D.; Janssen, M. A.; Hayes, A. G. +4 more
Saturn's rings are composed primarily of water ice with a small fraction of non-icy constituents that are likely both intrinsic and extrinsic in origin. The intrinsic material is thought to be characteristic of the ring progenitor, while the extrinsic material is derived from the continual stream of hypervelocity impacting micrometeoroids that pol…
Cassini microwave observations provide clues to the origin of Saturn's C ring
Nicholson, P. D.; Hedman, M. M.; Janssen, M. A. +6 more
Despite considerable study, Saturn's rings continue to challenge current theories for their provenance. Water ice comprises the bulk of Saturn's rings, yet it is the small fraction of non-icy material that is arguably more valuable in revealing clues about the system's origin and age. Herein, we present new measurements of the non-icy material fra…
Noncircular features in Saturn's rings IV: Absolute radius scale and Saturn's pole direction
Nicholson, Philip D.; French, Richard G.; McGhee-French, Colleen A. +6 more
We present a comprehensive solution for the geometry of Saturn's ring system, based on orbital fits to an extensive set of occultation observations of 122 individual ring edges and gaps. We begin with a restricted set of very high quality Cassini VIMS, UVIS, and RSS measurements for quasi-circular features in the C and B rings and the Cassini Divi…
Decadal timescale variability of the Enceladus plumes inferred from Cassini images
Ingersoll, Andrew P.; Ewald, Shawn P.
The brightness of the Enceladus plumes varies with position in the satellite's eccentric orbit, with altitude above the surface, and with time from one year to the next. Hedman et al. (2013, hereinafter H13) were the first to report these variations. They used data from Cassini's Visible and Infrared Mapping Spectrometer (VIMS). Here we present br…
Jupiter's auroral-related stratospheric heating and chemistry I: Analysis of Voyager-IRIS and Cassini-CIRS spectra
Fletcher, L. N.; Irwin, P. G. J.; Orton, G. S. +4 more
Auroral processes are evident in Jupiter's polar atmosphere over a large range in wavelength (X-ray to radio). In particular, previous observations in the mid-infrared (5-15 µm) have shown enhanced emission from CH4, C2H2 and C2H4 and further stratospheric hydrocarbon species in spatial …
Statistical study of Saturn's auroral electron properties with Cassini/UVIS FUV spectral images
Lamy, L.; Grodent, D.; Radioti, A. +3 more
About 2000 FUV spectra of different regions of Saturn's aurora, obtained with Cassini/UVIS from December 2007 to October 2014 have been examined. Two methods have been employed to determine the mean energy <;E> of the precipitating electrons. The first is based on the absorption of the auroral emission by hydrocarbons and the second uses the…
Cassini ISS observation of Saturn's north polar vortex and comparison to the south polar vortex
Dyudina, Ulyana A.; Ingersoll, Andrew P.; Ewald, Shawn P. +2 more
We present analyses of Saturn's north pole using high-resolution images captured in late 2012 by the Cassini spacecraft's Imaging Science Subsystem (ISS) camera. The images reveal the presence of an intense cyclonic vortex centered at the north pole. In the red and green visible continuum wavelengths, the north polar region exhibits a cyclonically…