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We present a self-consistent description of Titan’s aerosols-clouds-gases system and compare our results with the optical properties retrieved from measurements made by the Descent Imager/Spectral Radiometer (DISR) experiment on the Huygens probe (Tomasko, M.G. et al. [2008]. Planet. Space Sci. 56, 669–707). Our calculations include the condensation of methane, ethane and hydrogen cyanide on photochemical...
The lunar photometric function, which describes the dependency of the observed radiance on the observation geometry, is used for photometric correction of lunar visible/near-infrared data. A precise photometric correction parameter set is crucial for many applications including mineral identification and reflectance map mosaics. We present, for the first time, spectrally continuous photometric correction...
A new analysis of the Doppler tracking data from the Lunar Prospector mission in 1999 revealed a number of previously-unseen gravity anomalies at spatial scales as small as 27km over the nearside. The tracking data at low altitudes (50km or below) were better analyzed to resolve the nearside features without dampening from a power law constraint, by partitioning the gravity parameters concentrated...
The first of a new class of objects now known as main belt comets (MBCs) or “activated asteroids” was identified in 1996. The seven known members of this class have orbital characteristics of main belt asteroids yet exhibit dust ejection like comets. In order to constrain their physical and orbital properties we searched the Thousand Asteroid Light Curve Survey (TALCS; Masiero, J.R., Jedicke, R.,...
Stellar occultations by Saturn’s rings observed with the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft reveal that dusty features such as the F ring and the ringlets in the Encke and the Laplace Gaps have distinctive infrared transmission spectra. These spectra show a narrow optical depth minimum at wavelengths around 2.87μm. This minimum is likely due to the Christiansen...
We performed the first global survey of lunar regolith depths using Lunar Reconnaissance Orbiter Camera (LROC) data and the crater morphology method for determining regolith depth. We find that on both the lunar farside and in the nearside, non-mare regions, the regolith depth is twice as deep as it is within the lunar maria. Our data compare favorably with previous studies where such data exist....
The interval from L s =330° in Mars Year (MY) 26 until L s =84° in MY 27 has been used to compare and validate measurements from the Mars Global Surveyor Thermal Emission Spectrometer (TES) and the Mars Express Planetary Fourier Spectrometer (PFS). We studied differences between atmospheric temperatures observed by the two instruments. The best agreement between atmospheric temperatures...
For the boundaries of each chronostratigraphic epoch on Mars, we present systematically derived crater-size frequencies based on crater counts of geologic referent surfaces and three proposed “standard” crater size–frequency production distributions as defined by (a) a simple −2 power law, (b) Neukum and Ivanov, (c) Hartmann. In turn, these crater count values are converted to model-absolute ages...
Gliese 22 is a hierarchical triple red dwarf system formed by two close components, Aa and Ab, and a distant component, B, which is moving around the center of mass of the first two.The possible existence of a fourth very low-mass object (15 Jupiter mass) orbiting around component B was reported by Docobo et al. (Docobo, J.A. et al. [2007]. IAU Commun. 26, 3–4). In this probable scenario with four...
The Hapke (Hapke, B. [1981]. J. Geophys. Res. 86, 3039–3054) photometric model and its modifications are widely used to characterize telescopic, spacecraft, and laboratory observations of the bidirectional reflectance of particulate surfaces. Following work and methods laid out in a companion paper (Helfenstein, P., Shepard, M.K. [2011]. Icarus, in press), we deconstruct the Hapke model and, separating...
We report new radar observations of E-class Asteroid 64 Angelina and M-class Asteroid 69 Hesperia obtained with the Arecibo Observatory S-band radar (2480MHz, 12.6cm). Our measurements of Angelina’s radar bandwidth are consistent with reported diameters and poles. We find Angelina’s circular polarization ratio to be 0.8±0.1, tied with 434 Hungaria for the highest value observed for main-belt asteroids...
The analysis of all suitable images taken of Neptune with the Wide Field Planetary Camera 2 on the Hubble Space Telescope between 1994 and 2008 revealed the following results. The activity of discrete cloud features located near Neptune’s tropopause remained roughly constant within each year but changed significantly on the time scale of ∼5years. Discrete clouds covered 1% of the disk on average,...
We have used more than 4years of Mars Express ion data to estimate the escape of heavy ions (O+,O2+ and CO2+) from Mars. To take the limited field of view of the instrument into account, the data has been binned into spatial bins and angular bins to create average distribution functions for different positions in the near Mars space. The net escape flux for the studied low solar activity period, between...
This study explores the geophysical implications of two compositional models recently proposed for Ceres, which assume that the dwarf planet is a homogeneous mixture of chondritic material devoid with free water. In order to reproduce Ceres’ density, the rock density has to be offset by the presence of porosity and/or an abundance of hydrated salts resulting from the extensive hydration and oxidation...
Numerical integrations of the equations of motion of the giant planets and scattering particles show that there is a possible orbital itinerary that a particle may follow from a scattering mode up to a stable position near the orbit of 2004 XR 190 . This orbital evolution requires that the particle gets trapped in a mean motion resonance with Neptune coupled with the Kozai resonance. Imposing...
The European Space Agency (ESA) Rosetta spacecraft (Schulz, R., Alexander, C., Boehnhardt, H., Glassmeier, K.H. (Eds.) [2009]. “ROSETTA – ESA”) will encounter Comet 67P/Churyumov-Gerasimenko in 2014 and spend the next 18months in the vicinity of the comet, permitting very high spatial and spectral resolution observations of the coma and nucleus. During this time, the heliocentric distance of the comet...
We propose a detailed model for the formation of the lunar crater Hyginus, the associated Hyginus rille, a series of collapse pits along the rille, and what we identify as a blanket of pyroclasts surrounding the crater. We show that the geometry of the rille graben is consistent with its initiation by the intrusion of a dike that did not breach the surface, and that Hyginus crater may be a caldera...
The chromophores responsible for coloring the jovian atmosphere are embedded within Jupiter’s vertical aerosol structure. Sunlight propagates through this vertical distribution of aerosol particles, whose colors are defined by ϖ 0 (λ), and we remotely observe the culmination of the radiative transfer as I/F(λ). In this study, we employed a radiative transfer code to retrieve ϖ 0 (λ)...
Lithospheric strength can be used to estimate the heat flow at the time when a given region was deformed, allowing us to constrain the thermal evolution of a planetary body. In this sense, the high (>300km) effective elastic thickness of the lithosphere deduced from the very limited deflection caused by the north polar cap of Mars indicates a low surface heat flow for this region at the present...
Laser-induced breakdown spectroscopy (LIBS) was used to quantitatively analyze 195 rock slab samples with known bulk chemical compositions, 90 pressed-powder samples derived from a subset of those rocks, and 31 pressed-powder geostandards under conditions that simulate the ChemCam instrument on the Mars Science Laboratory Rover (MSL), Curiosity. The low-volatile (<2wt.%) silicate samples (90 rock...
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