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The composition and structure of the Enceladus plume
Hansen, C. J.; Hendrix, A. R.; West, R. A. +8 more
The Cassini Ultraviolet Imaging Spectrograph (UVIS) observed an occultation of the Sun by the water vapor plume at the south polar region of Saturn's moon Enceladus. The Extreme Ultraviolet (EUV) spectrum is dominated by the spectral signature of H2O gas, with a nominal line-of-sight column density of 0.90 ± 0.23 × 1016 cm
Seasonal changes in Titan's meteorology
West, R. A.; Schaller, E. L.; McEwen, A. S. +5 more
The Cassini Imaging Science Subsystem has observed Titan for ∼1/4 Titan year, and we report here the first evidence of seasonal shifts in preferred locations of tropospheric methane clouds. South-polar convective cloud activity, common in late southern summer, has become rare. North-polar and northern mid-latitude clouds appeared during the approa…
A fracture history on Enceladus provides evidence for a global ocean
Patthoff, D. Alex; Kattenhorn, Simon A.
The region surrounding the south pole of Saturn's moon Enceladus shows a young, pervasively fractured surface that emanates enough heat to be detected by the Cassini spacecraft. To explain the elevated heat and eruptive icy plumes originating from large cracks (informally called “tiger stripes”) in the surface, many models implicitly assume a glob…
The evolution of Titan's detached haze layer near equinox in 2009
West, Robert A.; Turtle, Elizabeth P.; Lavvas, Panayotis +5 more
Saturn's moon Titan has a massive atmosphere laden with layers of photochemical haze. We report a recent dramatic change in the vertical structure of this haze, with a persistent ‘detached’ layer dropping in altitude from over 500 km to only 380 km between 2007 and 2010. The detached haze layer appears to be a well-defined tracer for Titan's merid…
Evolution of the equatorial oscillation in Saturn's stratosphere between 2005 and 2010 from Cassini/CIRS limb data analysis
Flasar, F. M.; Bézard, B.; Fouchet, T. +2 more
We present an analysis of thermal infrared spectra acquired in limb viewing geometry by Cassini/CIRS in February 2010. We retrieve vertical profiles of Saturn's stratospheric temperature from 20 hPa to 10-2 hPa, at 9 latitudes between 20°N and 20°S. Using the gradient thermal wind equation, we derive a map of the zonal wind field. Both …
Simultaneous Cassini VIMS and UVIS observations of Saturn's southern aurora: Comparing emissions from H, H2 and H3+ at a high spatial resolution
Brown, R. H.; Baines, K. H.; Badman, S. V. +7 more
Here, for the first time, temporally coincident and spatially overlapping Cassini VIMS and UVIS observations of Saturn's southern aurora are presented. Ultraviolet auroral H and H2 emissions from UVIS are compared to infrared H3+ emission from VIMS. The auroral emission is structured into three arcs - H, H2
Limits of Enceladus's ice shell thickness from tidally driven tiger stripe shear failure
Pappalardo, Robert T.; Olgin, John G.; Smith-Konter, Bridget R.
Enceladus's south polar thermal anomaly and water-rich plumes suggest the existence of a subsurface ocean, which is overlain by an ice shell of uncertain thickness. Our objective is to constrain Enceladus's ice shell thickness, through assessment of tidally driven Coulomb failure of Enceladus's tiger stripe faults. We find that thin to moderate ic…
Intense plasma wave emissions associated with Saturn's moon Rhea
Schippers, P.; Gurnett, D. A.; Russell, C. T. +7 more
Measurements by the Cassini spacecraft during a close flyby of Saturn's moon Rhea on March 2, 2010, show the presence of intense plasma waves in the magnetic flux tube connected to the surface of the moon. Three types of waves were observed, (1) bursty electrostatic waves near the electron plasma frequency, (2) intense whistler-mode emissions belo…
Location of Saturn's northern infrared aurora determined from Cassini VIMS images
Brown, R. H.; Baines, K. H.; Dougherty, M. K. +6 more
The location of Saturn's northern infrared aurora is described in detail using 12 selected images acquired by Cassini VIMS during 2006-2008. Bright main oval arcs and prevalent polar features are displayed, which do not exhibit a preferred local time or spatial extent. The average equatorward limit of the aurora was determined using a best fit cir…
Magnetic signatures of a tenuous atmosphere at Dione
Dougherty, Michele K.; Saur, Joachim; Simon, Sven +2 more
We present Cassini magnetic field observations from the only two close flybys (16DI and 129DI) of Saturn's icy satellite Dione which have been carried out so far. Data from 16DI show a weak field perturbation in the upstream region, indicative of a tenuous atmosphere around the satellite. By applying an analytical model of the perturbations caused…