Search Publications
Multi-instrument analysis of electron populations in Saturn's magnetosphere
Schippers, P.; André, N.; Gurnett, D. A. +10 more
We analyze the radial distribution of electron populations inside 20 Rs in Saturn's magnetosphere, and we calculate moments for these populations by a forward modeling method using composite spectra produced by the CAPS/ELS (0.6 eV to 26 keV) and the MIMI/LEMMS (15 keV to 10 MeV) instruments on board Cassini. We first calculate and harm…
The identification of liquid ethane in Titan's Ontario Lacus
Sotin, C.; Barnes, J. W.; Brown, R. H. +7 more
Titan was once thought to have global oceans of light hydrocarbons on its surface, but after 40 close flybys of Titan by the Cassini spacecraft, it has become clear that no such oceans exist. There are, however, features similar to terrestrial lakes and seas, and widespread evidence for fluvial erosion, presumably driven by precipitation of liquid…
Hydrocarbon lakes on Titan: Distribution and interaction with a porous regolith
Callahan, P.; Gim, Y.; Stofan, E. +11 more
Synthetic Aperture Radar (SAR) images of Titan's north polar region reveal quasi-circular to complex features which are interpreted to be liquid hydrocarbon lakes. We investigate methane transport in Titan's hydrologic cycle using the global distribution of lake features. As of May 2007, the SAR data set covers ~22% of the surface and indicates mu…
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…
Slow dust in Enceladus' plume from condensation and wall collisions in tiger stripe fractures
Schmidt, Jürgen; Spahn, Frank; Kempf, Sascha +1 more
One of the spectacular discoveries of the Cassini spacecraft was the plume of water vapour and icy particles (dust) originating near the south pole of Saturn's moon Enceladus. The data imply considerably smaller velocities for the grains than for the vapour, which has been difficult to understand. The gas and dust are too dilute in the plume to in…
Titan's inventory of organic surface materials
Kirk, Randolph L.; Lorenz, Ralph D.; Janssen, Michael A. +13 more
Cassini RADAR observations now permit an initial assessment of the inventory of two classes, presumed to be organic, of Titan surface materials: polar lake liquids and equatorial dune sands. Several hundred lakes or seas have been observed, of which dozens are each estimated to contain more hydrocarbon liquid than the entire known oil and gas rese…
Titan’s Rotation Reveals an Internal Ocean and Changing Zonal Winds
Iess, Luciano; Stiles, Bryan W.; Kirk, Randolph L. +6 more
Cassini radar observations of Saturn’s moon Titan over several years show that its rotational period is changing and is different from its orbital period. The present-day rotation period difference from synchronous spin leads to a shift of ~0.36° per year in apparent longitude and is consistent with seasonal exchange of angular momentum between th…
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…
An update to a Saturnian longitude system based on kilometric radio emissions
Gurnett, D. A.; Kurth, W. S.; Averkamp, T. F. +2 more
The period of Saturn kilometric radiation modulation as determined by Voyager forms the basis for a longitude system (SLS) recognized by the International Astronomical Union. However, Ulysses and Cassini observations have shown that this modulation period varies by the order of one percent on timescales of a few years and, hence, does not represen…