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This paper discusses the effect of tides raised by Saturn on its co-orbital satellites Janus and Epimetheus, and its consequences on the long-term evolution of the co-orbital horseshoe pattern of those moons. This tidal effect is found to produce a loosening of the co-orbital lock of Janus and Epimetheus. The increase of the difference D between their semi-major axes under this process is estimated...
It is generally agreed that a dense CO 2 -dominant atmosphere was necessary in order to keep early Mars warm and wet. However, current models have not been able to produce surface temperature higher than the freezing point of water. Most sulfate minerals discovered on Mars are dated no earlier than the Hesperian, despite likely much stronger volcanic activities and more substantial release...
While extratropical cyclones cannot be expected in Titan’s barotropic troposphere, tropical cyclones which gain their energy from the latent heat of sea evaporation cannot be entirely dismissed over Titan’s polar hydrocarbon seas. The most essential condition for the genesis of tropical cyclones on Titan is a methane-rich composition of the polar seas. The most likely season for Titan’s hypothetical...
Hydrated silica is found in a variety of martian deposits within aqueously altered mineral suites. Its common occurrence is attributed to its ease of formation in different weathering environments. Because of its presence in disparate units, hydrated silica makes a good tracer mineral to compare otherwise dissimilar martian deposits and relate their relative degrees of aqueous alteration. This work...
The LIDAR instrument on the Phoenix mission obtained measurements of atmospheric dust and clouds from the surface in the Arctic region of Mars (68.22°N, 234.25°E) during late spring through the middle of summer. The observed vertical distribution of dust indicated that the planetary boundary layer (PBL) was evenly mixed up to heights of 4km by daytime convection and turbulence. The values of the dust...
We present a 3D general circulation model of Pluto and Triton’s atmospheres, which uses radiative–conductive–convective forcing. In both the Pluto and Triton models, an easterly (prograde) jet is present at the equator with a maximum magnitude of 10–12ms −1 and 4ms −1 , respectively. Neither atmosphere shows any significant overturning circulation in the meridional and vertical directions...
We present an updated analysis of Jupiter’s equatorial meteorology from Cassini observations. For two months preceding the spacecraft’s closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are relatively...
We analyse ground-based infrared observations of H3+ emission from the upper atmosphere of Uranus using Gemini North/GNIRS, NASA IRTF/SpeX and VLT/CRIRES. These observations were obtained on 15 different nights in late 2011, between day-of-year 251 (5th of September) and 340 (6th of December). The equinox of Uranus occurred in late 2007 and these recent observations quantify the behaviour of the planet’s...
The Uranian atmosphere was observed in August 2009 from 0.8 to 1.8 μm using the near-infrared spectrometer, SpeX, at NASA’s Infrared Telescope Facility. The observations had a spectral resolution of R=1200 and an average seeing of between 0.5″ in the H-Band (1.4–1.8μm) and 0.6″ in the I-Band (0.8–0.9μm). The reduced data were analyzed with a multiple-scattering retrieval code. We were able to reproduce...
Mercury’s sodium exosphere has been observed only few times with high spectral resolution from ground based observatories enabling the analysis of the emission spectra. These observations highlighted the energetic state of the sodium exospheric atoms relative to the surface temperature. More recently, the Doppler shift of the exospheric Na atoms was measured and interpreted as consistent with an exosphere...
Lunar basin-forming impacts produce enormous volumes (>10 5 km 3 ) of impact melt. All known basin-forming impacts combined may produce ∼10 8 km 3 of impact melt, ∼1/20th the volume of the lunar crust. Despite their volumetric importance, the geology and petrology of massive deposits of impact melt on the Moon have been little studied, in part because most basin...
Evidence for relaxation of impact crater topography has been observed on many icy satellites, including those of Saturn, and the magnitude of relaxation can be related to past heat flow (e.g. Moore, J.M., Schenk, P.M., Bruesch, L.S., Asphaug, E., McKinnon, W.B. [2004]. Icarus 171, 421–443; Dombard, A.J., McKinnon, W.B. [2006]. J. Geophys. Res. 111, E01001. http://dx.doi.org/10.1029/2005JE002445)....
We report results from monitoring Pluto’s 0.8 to 2.4μm reflectance spectrum with IRTF/SpeX on 65 nights over the dozen years from 2001 to 2012. The spectra show vibrational absorption features of simple molecules CH 4 , CO, and N 2 condensed as ices on Pluto’s surface. These absorptions are modulated by the planet’s 6.39day rotation period, enabling us to constrain the longitudinal...
We have studied the spectral reflectance properties of the CM2 xenolith-bearing howardite PRA 04401, intimate and areal mixtures of a eucrite (Millbillillie) and a CM2 chondrite (Murchison), and a mineralogically diverse suite of 12 HED meteorites. The main goal is to ascertain whether the presence of CM2-type material can be discriminated from grain size variations in HEDs. This project was motivated...
Near-InfraRed (NIR) data obtained at the Moon by the SIR-2 instrument aboard Chandrayan-1 have been analyzed and classified according to their spectral absorption characteristics. This approach yielded a new NIR map, based on 10 spectral categories that we have identified, which cover a substantial portion of the lunar nearside. The inferred distribution of materials that share similar reflectance...
We present the first results on solar occultations performed with the UV channel of SPICAM, on board Mars Express. From the dataset of over 900 occultations (performed between April 2004 and October 2011), about 640 atmospheric profiles of the martian atmosphere were derived. This dataset, spanning four martian years, allows characterization of the seasonal evolution and inter-annual comparisons of...
Irregular satellites are dormant comet-like bodies that reside on distant prograde and retrograde orbits around the giant planets. They are likely to be captured objects. Dynamical modeling work indicates they may have been caught during a violent reshuffling of the giant planets ∼4Gy ago (Ga) as described by the so-called Nice model. According to this scenario, giant planet migration scattered tens...
We study K-type asteroids in the broad surroundings of the Eos family because they seem to be intimately related, according to their colours measured by the Sloan Digital Sky Survey. Such ‘halos’ of asteroid families have been rarely used as constraints for dynamical studies to date. We explain its origin as bodies escaping from the family ‘core’ due to the Yarkovsky semimajor-axis drift and interactions...
We describe the theory and the numerical model used to simulate Doppler-broadened resonant emission lines for any type of velocity function distribution. The field of application of this theoretical model of radiative transfer is particularly well suited for the study of weakly dense atmospheres which are far from local thermodynamic equilibrium (as is the case for most planetary upper atmospheres/exospheres)...
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