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Four broad spectral features were identified in far-infrared limb spectra from the Cassini Composite Infrared Spectrometer (CIRS), two of which have not been identified before. The features are broader than the spectral resolution, which suggests that they are caused by particulates in Titan's stratosphere. We derive here the spectral properties and variations with altitude for these four features...
We report observations of Io that were conducted on UT 12 November 2002 with the NIRSPEC spectrometer, coupled to the adaptive optics system, on the 10-m Keck II telescope. We detected a bright eruption in the Ra Patera area, with a color (H–K′ band) temperature of 1031±110 K over an effective area of 1.5±0.2 km2. The eruption was associated with a hot plume, which revealed itself through SO emission...
Since their discovery in Voyager images, the origin of the bright polar caps of Ganymede has intrigued investigators. Some models attributed the polar cap formation to thermal migration of water vapor to higher latitudes, while other models implicated plasma bombardment in brightening ice. Only with the arrival of Galileo at Jupiter was it apparent that Ganymede possesses a strong internal magnetic...
A self-consistent chemical kinetic model of the Venus atmosphere at 0–47 km has been calculated for the first time. The model involves 82 reactions of 26 species. Chemical processes in the atmosphere below the clouds are initiated by photochemical products from the middle atmosphere (H 2 SO 4 , CO, S x ), thermochemistry in the lowest 10 km, and photolysis of S 3 ....
For impact craters with dimensions such as the Ries crater (corresponding to a 1 km meteorite) it has become a standard reference in textbooks on planetary science that under terrestrial conditions distal transfer of boulders may reach as far as 200 km. In order to test this assumption we simulated the impact-induced ballistic transfer of limestone boulders ejected out of the Ries crater and have...
The geographic signature of dune distribution and self-organization as measured by the R-statistic offers a viewpoint on the geography of crescentic eolian systems and proposes an index from which to determine the degree of self-organization across a variety of spatial scales. Fields of simple dunes (dome, barchan, barchan-seif) are comparatively less regular in distribution than are those fields,...
The quantitative measurement of surface roughness of planetary surfaces at all scales provides insights into geological processes. A characterization of roughness variations at the scale of a few tens of meters is proposed that complements the analysis of local topographic data of the martian surface at kilometer scale, as achieved from the Mars Orbiter Laser Altimeter (MOLA) data, and at the subcentimeter...
We report the detection of 13 CH 3 D in Titan's stratosphere from Cassini/CIRS infrared spectra near 8.7 μm. Fitting simultaneously the ν6 bands of both 13 CH 3 D and 12 CH 3 D and the ν4 band of CH 4 , we derive a D/H ratio equal to 1.32−0.11+0.15×10−4 and a 12 C/ 13 C ratio in deuterated methane of 82−18+27, consistent with...
Some recent MER Rover Opportunity results on ancient sedimentary rocks from Mars describe sandstones originated from the chemical weathering of olivine basalts by acidic waters [Squyres, S.W., Knoll, A.H., 2005. Earth Planet. Sci. Lett. 240, 1–10]. The absence of protective components in early Mars atmosphere forced any possible primordial life forms to deal with high doses of UV radiation. A similar...
We study the possibility that the mutual interactions between Jupiter and Saturn prevented Type II migration from driving these planets much closer to the Sun. Our work extends previous results by Masset and Snellgrove [Masset, F., Snellgrove, M., 2001. Mon. Not. R. Astron. Soc. 320, L55–L59], by exploring a wider set of initial conditions and disk parameters, and by using a new hydrodynamical code...
We have identified a number of gullies that could be aqueous in origin near or at the rim of several impact craters in Utopia Planitia and western Elysium Planitia (30.0°–59.0° N; 241.0°–291.0° W). Based on the sharpness of their incisions and the general absence of superposed craters, we ascribe a relatively recent origin to the gullies. Scalloped depressions are commonplace throughout the region,...
In the fall of 2005, a dedicated meteor observing campaign was carried out by the Panoramic Camera (Pancam) onboard the Mars Exploration Rover (MER) Spirit to determine the viability of using MER cameras as meteor detectors and to obtain the first experimental estimate of the meteoroid flux at Mars. Our observing targets included both the sporadic meteoroid background and two predicted martian meteor...
We perform an optical characterization of UV laser ablated silicates (olivine, pyroxene), starting from their reflectance spectra in the 0.3–2.5 μm spectral range. The goal is to provide useful tools to model space weathering effects on surfaces of asteroids and TNOs (trans-neptunian objects). We determine that the reddening and darkening spectral trend is compatible with the Hapke's space weathering...
Hubble Space Telescope observations of Uranus- and Neptune-crossing object (65489) Ceto/Phorcys (provisionally designated 2003 FX 128 ) reveal it to be a close binary system. The mutual orbit has a period of 9.554±0.011 days and a semimajor axis of 1840±48 km. These values enable computation of a system mass of (5.41±0.42)×1018 kg. Spitzer Space Telescope observations of thermal emission at...
Slope streaks are surficial mass movements that are abundant in the dust-covered regions of Mars. Targeting of slope streaks seen in Viking images with the Mars Orbiter Camera provides observations of slope streak dust activity over two to three decades. In all study areas, new and persisting dark slope streaks are observed. Slope streaks disappeared in one area, with persisting streaks nearby. New...
We have made near-IR spectral observations of the very young (5.75 Myr) S-type asteroid 832 Karin, well sampled in rotational phase over its 18.35-h period. We find no significant variations in its reflectance spectrum. Karin, the brightest member of the Karin cluster (a sub-family of the larger, older Koronis dynamical family), was shown to be exceptionally young by Nesvorný et al. [Nesvorný, D.,...
The global shape of Europa is controlled by tidal and rotational potentials and possibly by lateral variations in ice shell thickness. We use limb profiles from four Galileo images to determine the best-fit hydrostatic shape, yielding a mean radius of 1560.8±0.3 km and a radius difference a−c of 3.0±0.9 km, consistent with previous determinations and inferences from gravity observations. Adding long-wavelength...
Current methods for deriving thermal inertia from spacecraft observations of planetary brightness temperature generally assume that surface properties are uniform for any given observation or co-located set of observations. As a result of this assumption and the nonlinear relationship between temperature and thermal inertia, sub-pixel horizontal heterogeneity may yield different apparent thermal inertia...
Thermal inertia derivation techniques generally assume that surface properties are uniform at horizontal scales below the footprint of the observing instrument and to depths of several decimeters. Consequently, surfaces with horizontal or vertical heterogeneity may yield apparent thermal inertia which varies with time of day and season. To investigate these temporal variations, we processed three...
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