Search Publications
Analysis of Saturn’s thermal emission at 2.2-cm wavelength: Spatial distribution of ammonia vapor
Janssen, M. A.; Allison, M.; Ingersoll, A. P. +3 more
This work focuses on determining the latitudinal structure of ammonia vapor in Saturn’s cloud layer near 1.5 bars using the brightness temperature maps derived from the Cassini RADAR (Elachi et al. [2004], Space Sci. Rev. 115, 71-110) instrument, which works in a passive mode to measure thermal emission from Saturn at 2.2-cm wavelength. We perform…
Synergistic observations of Io’s atmosphere in 2010 from HST-COS in the mid-ultraviolet and IRTF-TEXES in the mid-infrared
Tsang, Constantine C. C.; Spencer, John R.; Jessup, Kandis Lea
We report on mid-UV spectroscopy of Io’s SO2 atmosphere from the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST), and compare to contemporaneous ground-based mid-infrared spectroscopy of the atmosphere. Our motivation is to evaluate the consistency of atmospheric parameters derived by different observational techni…
Auroral electron precipitation and flux tube erosion in Titan’s upper atmosphere
Coates, A. J.; Jones, G. H.; Wellbrock, A. +4 more
Cassini dasta shows that Titan’s atmosphere strongly depletes the electron content in Saturn’s flux tubes, producing features known as electron bite-outs, which indicate that the flux of auroral electrons decreases over time. To understand this process we have developed a time-dependent two-stream model, which uses field line geometries and drift …
The behavior of spokes in Saturn's B ring
Porco, C. C.; Spitale, J. N.; Mitchell, C. J. +1 more
We present the first results from Cassini ISS observations aimed at determining both the short-term and long-term behavior of the spokes in Saturn's B ring. We have observed multiple spokes which appear between images where there was not a spoke before. The radial termini of these new spokes expand radially at ∼0.5 km/s in both the inward and outw…
Local spectrophotometric properties of pyroclastic deposits at the Lavoisier lunar crater
Besse, S.; Josset, J. -L.; Haruyama, J. +5 more
We present a study of the Lavoisier lunar crater combining photometric data from the AMIE camera (SMART-1 mission) and hyperspectral data from the Moon Mineralogy Mapper M3 (Chandrayaan-1 mission), with a special emphasis on the pyroclastic deposits considered to be present on the crater floor. The photometric parameters are in agreemen…
Does ice float in Titan’s lakes and seas?
Lunine, Jonathan I.; Hofgartner, Jason D.
We model Titan’s lakes and seas as methane-ethane-nitrogen systems and model the buoyancy of solids in these systems assuming thermodynamic equilibrium. We find that ice will float in methane-rich lakes for all temperatures below the freezing point of pure methane and that ice will also float in ethane-rich seas provided the ice has an air porosit…
Venus nitric oxide nightglow mapping from SPICAV nadir observations
Bertaux, J. -L.; Gérard, J. -C.; Stiepen, A. +2 more
Nitric oxide δ (190-240 nm) and γ (255-270 nm) bands have been observed on the Venus nightside with Venus Express SPICAV instrument operated in the nadir mode. These ultraviolet emissions arise from the de-excitation of NO molecules created by radiative recombination of O(3P) and N(4S) atoms. These atoms are produced on the d…
Saturn’s ring temperatures at equinox
Spilker, Linda; Ferrari, Cecile; Morishima, Ryuji
Modeling the thermal emission of Saturn’s rings is challenging due to the numerous heating sources as well as the structural properties of the disk and of the particles that are closely related. At equinox, however, rings are externally heated by Saturn alone and the problem is somewhat simplified. We test the abilities of our current models to re…
Hubble observations of Jupiter’s north-south conjugate ultraviolet aurora
Bonfond, B.; Clarke, J. T.; Gérard, J. -C. +2 more
Comparisons of the northern and southern far ultraviolet (UV) auroral emissions of Jupiter from the Hubble Space Telescope (HST) or any other ultraviolet imager have mostly been made so far on a statistical basis or were not obtained with high sensitivity and resolution. Such observations are important to discriminate between different mechanisms …
The smallest particles in Saturn’s A and C Rings
Nicholson, Philip D.; Hedman, Matthew M.; Harbison, Rebecca A.
Radio occultations of Saturn’s main rings by spacecraft suggest a power law particle size-distribution down to sizes of the order of 1 cm (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 betw…