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 …
Powering prolonged hydrothermal activity inside Enceladus
Postberg, Frank; Sotin, Christophe; Čadek, Ondřej +4 more
Geophysical data from the Cassini spacecraft imply the presence of a global ocean underneath the ice shell of Enceladus1, only a few kilometres below the surface in the South Polar Terrain2-4. Chemical analyses indicate that the ocean is salty5 and is fed by ongoing hydrothermal activity6-8. In order to …
Titan's Topography and Shape at the End of the Cassini Mission
Hayes, A. G.; Iess, L.; Stiles, B. W. +6 more
With the conclusion of the Cassini mission, we present an updated topographic map of Titan, including all the available altimetry, SARtopo, and stereophotogrammetry topographic data sets available from the mission. We use radial basis functions to interpolate the sparse data set, which covers only ∼9% of Titan's global area. The most notable updat…
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…
Topographic Constraints on the Evolution and Connectivity of Titan's Lacustrine Basins
Lorenz, R. D.; Hayes, A. G.; Kirk, R. L. +11 more
The topography provided by altimetry, synthetic aperture radar-topography, and stereo radargrammetry has opened new doors for Titan research by allowing for quantitative analysis of morphologic form. Using altimetry measurements, we show that Titan's Maria are consistent with an equipotential surface but that several filled lakes are found to be h…
Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan’s Ionosphere
Lewis, G. R.; Coates, A. J.; Kataria, D. O. +13 more
Cassini discovered a plethora of neutral and ionized molecules in Titan’s ionosphere including, surprisingly, anions and negatively charged molecules extending up to 13,800 u q-1. In this Letter, we forward model the Cassini electron spectrometer response function to this unexpected ionospheric component to achieve an increased mass res…
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…
Disruption of Saturn's quasi-periodic equatorial oscillation by the great northern storm
Fletcher, Leigh N.; Irwin, Patrick G. J.; Flasar, F. Michael +7 more
The equatorial middle atmospheres of the Earth1, Jupiter2 and Saturn3,4 all exhibit a remarkably similar phenomenon—a vertical, cyclic pattern of alternating temperatures and zonal (east-west) wind regimes that propagate slowly downwards with a well-defined multi-year period. Earth's quasi-biennial oscillation (QBO…
Thermally anomalous features in the subsurface of Enceladus's south polar terrain
Sotin, C.; Lorenz, R. D.; West, R. D. +15 more
Saturn's moon Enceladus is an active world. In 2005, the Cassini spacecraft witnessed for the first time water-rich jets venting from four anomalously warm fractures (called sulci) near its south pole1,2. Since then, several observations have provided evidence that the source of the material ejected from Enceladus is a large underground…