Search Publications
Sulfur volcanism on Io
Spencer, John; Yelle, Roger; Jessup, Kandis Lea
In February 2003, March 2003 and January 2004 Pele plume transmission spectra were obtained during Jupiter transit with Hubble's Space Telescope Imaging Spectrograph (STIS), using the 0.1″ wide slit and the G230LB grating. The STIS spectra covered the 2100-3100 Å wavelength regions and extended spatially along Io's limb encompassing the region dir…
Saturn's dynamic D ring
Nicholson, Philip D.; Porco, Carolyn C.; Hedman, Matthew M. +8 more
The Cassini spacecraft has provided the first clear images of the D ring since the Voyager missions. These observations show that the structure of the D ring has undergone significant changes over the last 25 years. The brightest of the three ringlets seen in the Voyager images (named D72), has transformed from a narrow, <40-km wide ringlet to …
Ceres lightcurve analysis—Period determination
Esquerdo, Gilbert A.; Sykes, Mark V.; Chamberlain, Matthew A.
The sidereal period of Ceres is refined from 9.075 h to 9.074170±0.000002, making use of recent and historical lightcurves spanning almost 50 years. An observed increase in the amplitude of the lightcurve with solar phase angle is consistent with bright, discrete albedo features contributing a greater fraction of light as the defect of illuminatio…
Spatially resolved cloud structure on Uranus: Implications of near-IR adaptive optics imaging
Sromovsky, L. A.; Fry, P. M.
Seven-band near-IR adaptive optics imaging of Uranus by the Keck II telescope during 2004, with the assistance of selected Hubble Space Telescope images, provides new constraints on the uranian vertical cloud structure and CH 4 mixing ratio, after tuned deconvolutions are applied to remove significant limb darkening distortions. The mos…
Gravity field and interior of Rhea from Cassini data analysis
Iess, Luciano; Tortora, Paolo; Rappaport, Nicole J. +5 more
The Cassini spacecraft encountered Rhea on November 26, 2005. Analysis of the Doppler data acquired at and around closest approach yields the mass of Rhea and the quadrupole moments of its gravity field with unprecedented accuracy. We obtained GM=153.9395±0.0018 kms which corresponds to a density of 1232.8±5.4 kgm. Our results for J and C are (7.9…
A Schumann-like resonance on Titan driven by Saturn's magnetosphere possibly revealed by the Huygens Probe
Berthelier, J. J.; Krasnoselskikh, V.; López-Moreno, J. J. +9 more
The low-frequency data collected with the antenna of the Permittivity, Wave and Altimetry experiment on board the Huygens Probe that landed on Titan on 14 January 2005 have been thoroughly analyzed considering different possible natural and artificial effects. Although a definite conclusion is still subject to the outcome of complementary inquirie…
Titan's surface from Cassini RADAR SAR and high resolution radiometry data of the first five flybys
Lorenz, R. D.; Janssen, M. A.; Stiles, B. +12 more
The first five Titan flybys with Cassini's Synthetic Aperture RADAR (SAR) and radiometer are examined with emphasis on the calibration and interpretation of the high-resolution radiometry data acquired during the SAR mode (SAR-radiometry). Maps of the 2-cm wavelength brightness temperature are obtained coincident with the SAR swath imaging, with s…
Enceladus: The likely dominant nitrogen source in Saturn's magnetosphere
Johnson, R. E.; Sittler, E. C.; Smith, H. T. +7 more
The spatial distribution of N + in Saturn's magnetosphere obtained from Cassini Plasma Spectrometer (CAPS) data can be used to determine the spatial distribution and relative importance of the nitrogen sources for Saturn's magnetosphere. We first summarize CAPS data from 15 orbits showing the spatial and energy distribution of the nitro…
HST observations of azimuthal asymmetry in Saturn's rings
French, Richard G.; Dones, Luke; Salo, Heikki +1 more
From 378 Hubble Space Telescope WFPC2 images obtained between 1996-2004, we have measured the detailed nature of azimuthal brightness variations in Saturn's rings. The extensive geometric coverage, high spatial resolution ( ∼300 kmpx), and photometric precision of the UBVRI images have enabled us to determine the dependence of the asymmetry amplit…
Long-term atmospheric variability on Uranus and Neptune
Hammel, H. B.; Lockwood, G. W.
Long-term photometric measurements of Uranus and Neptune through 2005 show variations in brightness. For Uranus, much of the variation can be interpreted as seasonal, i.e., caused by viewing angle changes of an oblate planet. The photometry suggests that if seasonal variations on Uranus are north-south symmetric, then the northern pole should begi…