Search Publications
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…
The Surface of Titan from NICMOS Observations with the Hubble Space Telescope
Terrile, Richard J.; Smith, Bradford A.; Owen, Tobias C. +1 more
From diffraction-limited images produced by the near-IR camera NICMOS aboard the Hubble Space Telescope we derived maps of Titan's surface in the methane windows near 1.1, 1.6, and 2.0 µm. Each part of Titan's atmosphere and surface was imaged at least twice over a time period of 24 h to look for moving clouds. Despite careful analysis we fo…
Model Calculations for Io's Atmosphere at Eastern and Western Elongations
Smyth, William H.; Wong, Mau C.
Numerical calculations are performed for Io's sublimation atmosphere at eastern and western elongations using an improved version of the multispecies hydrodynamic model first developed by Wong and Johnson (1996). Subsolar SO 2 frost temperatures of 113 and 120 K are adopted to cover a range of plausible atmospheric abundances that are c…
Pluto's Non-isothermal Surface
Lellouch, E.; Crovisier, J.; Coustenis, A. +4 more
We report on repeated far-infrared photometric observations of the Pluto-Charon system conducted in 1997 with the Infrared Space Observatory (ISO). These observations have led to the first detection of the system at 150 and 200 µm and to the first clear detection of its thermal lightcurve at 60 µm (and more marginally at 100 µm).…