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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…
Anomalous magnetosheath flows and distorted subsolar magnetopause for radial interplanetary magnetic fields
Glassmeier, K. H.; Plaschke, F.; McFadden, J. P. +5 more
On 12 August 2007 from 1436 to 1441 UT, when the five THEMIS probes (THA, THB, THC, THD, and THE) were located near the subsolar magnetopause, a sunward flow was observed in the magnetosheath. A fast anti-sunward flow (-280 km/s) was observed in the magnetosheath before the sunward flow. Although THA observed this fast anti-sunward flow, THC and T…
Phyllosilicates and sulfates at Endeavour Crater, Meridiani Planum, Mars
Arvidson, R. E.; Mustard, J. F.; Wray, J. J. +5 more
Phyllosilicates have been identified on the Martian surface from orbit, and are hypothesized to have formed under wet, non-acidic conditions early in the planet's history. Exposures of these minerals have not yet been examined by a landed mission. Using Mars Reconnaissance Orbiter data, we report the detection of phyllosilicate-bearing outcrops th…
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…
Ionospheric storms on Mars: Impact of the corotating interaction region
Barabash, S.; Lundin, R.; Woch, J. +5 more
Measurements made by the ASPERA-3 and MARSIS experiments on Mars Express have shown, for the first time, that space weather effects related to the impact of a dense and high pressure solar wind (corotating interaction region) on Mars cause strong perturbations in the martian induced magnetosphere and ionosphere. The magnetic barrier formed by pile…
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 …