Search Publications
Cassini imaging of Titan's high-latitude lakes, clouds, and south-polar surface changes
West, R. A.; Porco, C. C.; McEwen, A. S. +5 more
Cassini's Imaging Science Subsystem (ISS) has been observing Titan since April 2004, compiling a nearly global surface map and monitoring the surface and atmosphere for activity. Early images of the south-polar region revealed numerous dark surface features and contemporaneous convective cloud systems, suggesting the presence of hydrocarbon lakes …
Discovery of a north-south asymmetry in Saturn's radio rotation period
Gurnett, D. A.; Persoon, A. M.; Kurth, W. S. +5 more
For many years it has been known that Saturn emits intense radio emissions at kilometer wavelengths and that this radiation is modulated by the rotation of the planet at a rate that varies by up to one percent on a time scale of years. Recent radio observations from the Cassini spacecraft have revealed the appearance of a second component, with a …
Global pattern of Titan's dunes: Radar survey from the Cassini prime mission
Lorenz, Ralph D.; Radebaugh, Jani
We present a map of the orientation and extent of Titan's sand dunes derived from the complete radar imaging dataset from the Cassini prime mission. The 16,000 dune segments we have mapped cover ~8% of the Titan's surface (suggesting a total coverage of ~20%), are confined within 30° of the equator, and show local and regional deviations of dune o…
Fine jet structure of electrically charged grains in Enceladus' plume
Lewis, G. R.; Coates, A. J.; Russell, C. T. +18 more
By traversing the plume erupting from high southern latitudes on Saturn's moon Enceladus, Cassini orbiter instruments can directly sample the material therein. Cassini Plasma Spectrometer, CAPS, data show that a major plume component comprises previously-undetected particles of nanometer scales and larger that bridge the mass gap between previousl…
Discrete classification and electron energy spectra of Titan's varied magnetospheric environment
Coates, A. J.; Smith, H. T.; Young, D. T. +2 more
We analyse combined electron spectra across the dynamic range of both Cassini electron sensors in order to characterise the background plasma environment near Titan for 54 Cassini-Titan encounters as of May 2009. We characterise the encounters into four broad types: Plasma sheet, Lobe-like, Magnetosheath and Bimodal. Despite many encounters occurr…
Altitude of Saturn's aurora and its implications for the characteristic energy of precipitated electrons
Bonfond, B.; Clarke, J. T.; Gérard, J. -C. +4 more
Images of Saturn's aurora at the limb have been collected with the Advanced Camera for Surveys on board the Hubble Space Telescope. They show that the peak of Saturn's nightside emission is generally located 900-1300 km above the 1-bar level. On the other hand, methane and H2 columns overlying the aurora have been determined from the an…
A north-south difference in the rotation rate of auroral hiss at Saturn: Comparison to Saturn's kilometric radio emission
Gurnett, D. A.; Persoon, A. M.; Hospodarsky, G. B. +3 more
Broadband whistler-mode emissions, commonly observed by the Cassini spacecraft at high latitudes in Saturn's magnetosphere at frequencies below about 100 Hz, have characteristics very similar to auroral hiss observed at high latitudes in Earth's magnetosphere. In contrast to terrestrial auroral hiss, which shows no obvious rotational modulation, S…
Smoothness of Titan's Ontario Lacus: Constraints from Cassini RADAR specular reflection data
Lorenz, R. D.; Wye, L. C.; Zebker, H. A.
Cassini RADAR altimetry data collected on the 49th flyby of Titan (2008 December 21) over Ontario Lacus in Titan's south polar region provides strong evidence for an extremely smooth surface, with less than 3 mm rms surface height variation over the 100m-wide Fresnel zone. Histograms of the raw radar echoes imply a mirror-like specular reflection …
Cassini detection of Enceladus' cold water-group plume ionosphere
Coates, A. J.; Thomsen, M. F.; Wilson, R. J. +6 more
This study reports direct detection by the Cassini plasma spectrometer of freshly-produced water-group ions (O+, OH+, H2O+, H3O+) and heavier water dimer ions (HxO2)+ very close to Enceladus where the plasma begins to emerge from the plume. The data …
Detecting nanoparticles at radio frequencies: Jovian dust stream impacts on Cassini/RPWS
Gurnett, D. A.; Kaiser, M. L.; Meyer-Vernet, N. +1 more
We analyse wave observations by the Cassini/RPWS instrument performed during the Jovian fly-by, when the on-board dust analyser recorded dust streams which were interpreted as nanoparticles moving at about the solar wind speed. The observed wave pulses are produced by ionisation of dust grains impacting the spacecraft. Nanoparticles are detected b…