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Particle properties of individual fissure eruptions within Enceladus’ plume have been analyzed using high spatial resolution Visible and Infrared Mapping Spectrometer (VIMS) observations from the Cassini mission. To first order, the spectra of the materials emerging from Cairo, Baghdad and Damascus sulci are very similar, with a strong absorption band around 3µm due to water-ice. The band minimum...
We present a comprehensive solution for the geometry of Saturn’s ring system, based on orbital fits to an extensive set of occultation observations of 122 individual ring edges and gaps. We begin with a restricted set of very high quality Cassini VIMS, UVIS, and RSS measurements for quasi-circular features in the C and B rings and the Cassini Division, and then successively add suitably weighted additional...
We analyze several thousand Cassini ISS images in order to study the inner edge of the Keeler gap in Saturn's outer A ring. We find strong evidence for an m = 32 perturbation with a mean amplitude of radial variation of 4.5km. Phase analysis yields a pattern speed consistent with the mean motion of Prometheus, indicating that this pattern is generated by the 32:31 Inner Lindblad resonance with Prometheus...
The eccentric Maxwell ringlet in Saturn’s C ring is home to a prominent wavelike structure that varies strongly and systematically with true anomaly, as revealed by nearly a decade of high-SNR Cassini occultation observations. Using a simple linear “accordion” model to compensate for the compression and expansion of the ringlet and the wave, we derive a mean optical depth profile for the ringlet and...
We present a study of the behavior of Saturn’s A ring outer edge, using images and occultation data obtained by the Cassini spacecraft over a period of 8years from 2006 to 2014. More than 5000 images and 170 occultations of the A ring outer edge are analyzed. Our fits confirm the expected response to the Janus 7:6 Inner Lindblad resonance (ILR) between 2006 and 2010, when Janus was on the inner leg...
In 1988 Rosen and Lissauer identified an unusual wavelike feature in Saturn’s inner C ring as a bending wave driven by a nodal resonance with Titan (Science 241, 690). This is sometimes referred to as the −1:0 resonance since it occurs where the local nodal regression rate is approximately equal to −nT, where nT=22.577∘d−1 is Titan’s orbital mean motion. We have used a series of 44 stellar occultation...
The distribution of particle sizes in Saturn's rings roughly follows a truncated inverse power-law. Though it is well known that differential optical depths provide a way to probe the parameters of size distribution (i.e. Zebker et al. [1985] Icarus, 64, 531–548), the technique is complicated by the presence of self-gravity wakes which introduce a geometric dependence to the observed optical depth...
We have conducted a comprehensive survey of 22 sharp-edged ringlets and gaps in the Cassini Division of Saturn’s rings, making use of nearly 200 high-SNR stellar and radio occultation chords obtained by the Cassini VIMS, UVIS, and RSS instruments between 2005 and 2013. We measure eccentricities from as small as ae=80 m to nearly 30 km, free normal modes with amplitudes from ∼ 0.1 to 4.1 km, and detectable...
The spatial distribution of the tropospheric methane on Titan was measured using near-infrared spectroscopy. Ground-based observations at 1.5μm (H-band) were performed during the same night using instruments with adaptive optics at both the W.M. Keck Observatory and at the Paranal Observatory on 17 July 2014 UT. The integral field observations with SINFONI on the VLT covered the entire H-band at moderate...
We present an analysis of the VIMS solar occultations dataset, which allows us to extract vertically resolved information on the characteristics of Titan’s atmosphere between ∼100 and 700km with a vertical resolution of ∼10km. After a series of data treatment procedures to correct problems in pointing stability and parasitic light, 4 occultations out of 10 are retained. This sample covers different...
We present a comprehensive survey of sharp-edged features in Saturn’s C ring, using data from radio and stellar occultation experiments carried out by the Cassini spacecraft over a period of more than five years. Over 100 occultations are included in the combined data set, enabling us to identify systematic radial perturbations as small as 200m on the edges of ringlets and gaps. We systematically...
A comprehensive investigation of all available radio and stellar occultation data for the outer edge of Saturn’s B ring, spanning the period 1980–2010, confirms that the m=2 distortion due to the strong Mimas 2:1 inner Lindblad resonance circulates slowly relative to Mimas in a prograde direction, with a frequency Ω L =0.1819°d −1 . Our best-fitting model implies that the radial amplitude...
We present a photometric model of the rings of Saturn which includes the main rings and an F ring, inclined to the main rings, with a Gaussian vertical profile of optical depth. This model reproduces the asymmetry in brightness between the east and west ansae of the rings of Saturn that was observed by the Hubble Space Telescope (HST) within a few hours after the Earth ring-plane crossing (RPX) of...
Radio occultations of Saturn’s main rings by spacecraft suggest a power law particle size-distribution down to sizes of the order of 1cm (Marouf, E.A., Tyler, G.L., Zebker, H.A., Simpson, R.A., Eshleman, V.R. [1983]. Icarus 54, 189–211; Zebker, H.A., Marouf, E.A., Tyler, G.L. [1985]. Icarus 64, 531–548.). The lack of optical depth variations between ultraviolet and near-IR wavelengths indicate a lack...
Observations from Cassini VIMS and ISS show localized but extensive surface brightenings in the wake of the 2010 September cloudburst. Four separate areas, all at similar latitude, show similar changes: Yalaing Terra, Hetpet Regio, Concordia Regio, and Adiri. Our analysis shows a general pattern to the time-sequence of surface changes: after the cloudburst the areas darken for months, then brighten...
We have processed all images of Titan's surface acquired by the Visual and Infrared Mapping Spectrometer between 2004 and 2010, with the objective of producing seamless global mosaics of the surface in the six infrared atmospheric windows at 1.08, 1.27, 1.59, 2.03, 2.6–2.7 and 5μm. A systematic study of the photometry at 5μm, where haze scattering can be neglected, shows that the surface behaves to...
During the 58th close flyby of Titan (T58), the Cassini Visual and Infrared Mapping Spectrometer (VIMS) observed a specular reflection of sunlight from Titan’s Jingpo Lacus through the 5-μm methane window (Stephan, K. et al. [2010]. Geophys. Res. Lett. 37, L07104). The maximum intensity of this reflection is controlled by three basic factors: (1) the shape of the reflecting surface (its overall geometry...
Image photometry reveals that the F ring is approximately twice as bright during the Cassini tour as it was during the Voyager flybys of 1980 and 1981. It is also three times as wide and has a higher integrated optical depth. We have performed photometric measurements of more than 4800 images of Saturn’s F ring taken over a 5-year period with Cassini’s Narrow Angle Camera. We show that the ring is...
Cassini VIMS has obtained spatially resolved imaging spectroscopy data on numerous satellites of Saturn. A very close fly-by of Iapetus on September 10, 2007 provided the best data on the spectral signature and spatial extent of dark material on Iapetus. This Cassini Rev 49 Iapetus fly-by provided spatially resolved imaging spectroscopy data of the dark material and the leading/trailing side transition...
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