Search Publications
Tidal heating and the long-term stability of a subsurface ocean on Enceladus
Nimmo, Francis; Roberts, James H.
Tidal dissipation has been suggested as the heat source for the south polar thermal anomaly on Enceladus. We find that under present-day conditions and assuming Maxwellian behavior, tidal dissipation is negligible in the silicate core. Dissipation may be significant in the ice shell if the shell is decoupled from the silicate core by a subsurface …
Dunes on Titan observed by Cassini Radar
Lorenz, R. D.; Callahan, P.; Lunine, J. I. +13 more
Thousands of longitudinal dunes have recently been discovered by the Titan Radar Mapper on the surface of Titan. These are found mainly within ±30° of the equator in optically-, near-infrared-, and radar-dark regions, indicating a strong proportion of organics, and cover well over 5% of Titan's surface. Their longitudinal duneform, interactions wi…
Compositional mapping of Saturn's satellite Dione with Cassini VIMS and implications of dark material in the Saturn system
Nicholson, Philip D.; Baines, Kevin H.; Buratti, Bonnie J. +9 more
Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Dione provided key information for solving the riddle of the origin of the dark material in the Saturn system. The Dione VIMS data show a pattern of bombardment of fine, sub-0.5-µm diameter particles impacting the s…
Titan's middle-atmospheric temperatures and dynamics observed by the Cassini Composite Infrared Spectrometer
Nixon, Conor A.; Achterberg, Richard K.; Flasar, F. Michael +2 more
The Composite Infrared Radiometer-Spectrometer (CIRS) instrument, on the NASA Cassini Saturn orbiter, has been acquiring thermal emission spectra from the atmosphere of Titan since orbit insertion in 2004. Observation sequences for measuring stratospheric temperatures have been obtained using both a nadir mapping mode and a limb viewing mode. The …
Spectroscopy, morphometry, and photoclinometry of Titan's dunefields from Cassini/VIMS
Sotin, Christophe; Barnes, Jason W.; Rodriguez, Sebastien +10 more
Fine-resolution (500 m/pixel) Cassini Visual and Infrared Mapping Spectrometer (VIMS) T20 observations of Titan resolve that moon's sand dunes. The spectral variability in some dune regions shows that there are sand-free interdune areas, wherein VIMS spectra reveal the exposed dune substrate. The interdunes from T20 are, variously, materials that …
Solid tidal friction above a liquid water reservoir as the origin of the south pole hotspot on Enceladus
Sotin, C.; Tobie, G.; Čadek, O.
Earth, Jupiter's moon Io and Saturn's tiny moon Enceladus are the only solid objects in the Solar System to be sufficiently geologically active for their internal heat to be detected by remote sensing. Interestingly, the endogenic activity on Enceladus is only located on a specific region at the south pole, from which jets of water vapor and ice p…
The E-ring in the vicinity of Enceladus. II. Probing the moon's interior—The composition of E-ring particles
Kempf, S.; Postberg, F.; Srama, R. +4 more
The population of Saturn's outermost tenuous E-ring is dominated by tiny water ice particles. Active volcanism on the moon Enceladus, embedded in the E-ring, has since late 2005 been known to be a major source of particles replenishing the ring. Therefore particles in the vicinity of Enceladus may provide crucial information about the dynamical an…
The E ring in the vicinity of Enceladus. I. Spatial distribution and properties of the ring particles
Beckmann, U.; Kempf, S.; Postberg, F. +6 more
Saturn's diffuse E ring is the largest ring of the Solar System and extends from about 3.1R (Saturn radius R=60,330 km) to at least 8R encompassing the icy moons Mimas, Enceladus, Tethys, Dione, and Rhea. After Cassini's insertion into her saturnian orbit in July 2004, the spacecraft performed a number of equatorial as well as steep traversals thr…
A close look at Saturn's rings with Cassini VIMS
Drossart, Pierre; Nicholson, Philip D.; Hedman, Matthew M. +13 more
Soon after the Cassini-Huygens spacecraft entered orbit about Saturn on 1 July 2004, its Visual and Infrared Mapping Spectrometer obtained two continuous spectral scans across the rings, covering the wavelength range 0.35-5.1 µm, at a spatial resolution of 15-25 km. The first scan covers the outer C and inner B rings, while the second covers…
Hydrocarbons on Saturn's satellites Iapetus and Phoebe
Sotin, C.; Brown, R. H.; Baines, K. H. +24 more
Material of low geometric albedo ( p⩽0.1) is found on many objects in the outer Solar System, but its distribution in the saturnian satellite system is of special interest because of its juxtaposition with high-albedo ice. In the absence of clear, diagnostic spectral features, the composition of this low-albedo (or "dark") material is generally in…