Search Publications
Photochemistry of Saturn's Atmosphere. I. Hydrocarbon Chemistry and Comparisons with ISO Observations
Bézard, Bruno; Lellouch, Emmanuel; Moses, Julianne I. +3 more
To investigate the details of hydrocarbon photochemistry on Saturn, we have developed a one-dimensional diurnally averaged model that couples hydrocarbon and oxygen photochemistry, molecular and eddy diffusion, radiative transfer, and condensation. The model results are compared with observations from the Infrared Space Observatory (ISO) to place …
Photochemistry of Saturn's Atmosphere. II. Effects of an Influx of External Oxygen
Bézard, Bruno; Lellouch, Emmanuel; Moses, Julianne I. +3 more
We use a one-dimensional diurnally averaged model of photochemistry and diffusion in Saturn's stratosphere to investigate the influence of extraplanetary debris on atmospheric chemistry. In particular, we consider the effects of an influx of oxygen from micrometeoroid ablation or from ring-particle diffusion; the contribution from cometary impacts…
Saturn's Zonal Winds at Cloud Level
Sada, Pedro V.; Sanchez-Lavega, Agustín.; Rojas, José F.
We present an analysis of new cloud motion measurements in Saturn's atmosphere from Voyager 1 and 2 images and define a nominal zonal wind velocity vs latitude profile for the cloud top level that can be used as reference for the upcoming Cassini mission. Improvements over previous studies include: (i) twice the number of wind vectors used, (ii) i…
ISO-SWS Observations of Jupiter: Measurement of the Ammonia Tropospheric Profile and of the 15N/ 14N Isotopic Ratio
Drossart, Pierre; Bézard, Bruno; Lellouch, Emmanuel +4 more
We present the results of the Infrared Space Observatory Short Wavelength Spectrometer (ISO-SWS) observations of Jupiter related to ammonia. We focus on two spectral regions; the first one (the 10-µm region), ranging from 9.5 to 11.5 µm, probes atmospheric levels between 1 and 0.2 bar, while the second one (the 5-µm window), rang…
The Formation of Encke Meteoroids and Dust Trail
Reach, William T.; Sykes, Mark V.; Lien, David +1 more
We observed Comet 2P/Encke with the Infrared Space Observatory ISOCAM on July 14, 1997, from a particularly favorable viewing geometry above the comet's orbital plane and at a distance of 0.25 AU. A structured coma was observed, along with a long, straight dust trail. For the first time, we are able to observe the path of particles as they evolve …
Physical Properties of the Nucleus of Comet 2P/Encke
Fernández, Yanga R.; Weaver, Harold A.; A'Hearn, Michael F. +6 more
We report a new study of the nucleus of Comet 2P/Encke, which the CONTOUR spacecraft is scheduled to encounter in November 2003. During the comet's close approach to Earth in July 1997, we measured the mid-infrared thermal and optical scattered continua with data from the TIMMI instrument (imaging) at the ESO 3.6-m telescope (wavelength λ from 8 t…
A Coupled Model of Titan's Atmosphere and Ionosphere
Lara, L. M.; Rodrigo, R.; López-Moreno, J. J. +2 more
The paper deals with a coupled model of the upper atmosphere and ionosphere of Titan. The neutral atmosphere is described by a comprehensive photochemical model for 30° solar zenith angle with molecular and turbulent diffusive transport taken into account. At the upper boundary (1430 km) escaping flux of light molecules is included in boundary con…
Exobiological Implications of a Possible Ammonia-Water Ocean inside Titan
Fortes, A. D.
Models of Titan's thermal history indicate that an ocean consisting of an ammonia-water solution, as much as 200 km deep, is presently concealed beneath a crust of water ice. Conditions within this hypothetical ocean are discussed here and compared with conditions in terrestrial biomes. These conditions, while extreme by terrestrial standards, are…
Spatially Resolved Spectroscopy of Io's Pele Plume and SO 2 Atmosphere
McGrath, Melissa A.; Spencer, John R.; Belton, Michael J. S. +1 more
We report on the first successful, spatially resolved spectroscopic observations of Io's SO 2 atmosphere. Observations made with the Hubble Space Telescope Faint Object Spectrograph on 1 August 1996 using the 0.26 '' aperture have provided detections of SO 2 gas in absorption in three locations on the Io disk: the …
The Distribution and Physical State of H 2O on Charon
Buie, M. W.; Grundy, W. M.
We present new 1.4- to 2.5-µm geometric albedo spectra of Charon taken with HST/NICMOS in 1998. These new data provide global coverage of the surface with four spectra at evenly spaced longitudes. The surface of Charon is seen to be globally dominated by H 2O ice. The data indicate that the ice is in the crystalline phase at a tem…