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Simulations of the surface temperature and atmospheric humidity with a modern Mars climate model (MCD) and with Phoenix data are used to study the conditions for a liquefaction of brines as a function of latitude and season. The results show that, in the presence of appropriate salts, liquid cryobrines can in course of the diurnal cycle temporarily evolve at high latitudes on Mars’ current climate...
Estimates of the moments of inertia of Titan, as separately deduced from its gravitational field and spin pole orientation, are quite different. This discrepancy can be resolved if Titan is either not precessing as a rigid body (e.g. if the shell is decoupled from the interior by an ocean), or if the spin pole is not fully damped (e.g. due to atmospheric excitation). By the end of the Cassini mission,...
We model the cratering of the Moon and terrestrial planets from the present knowledge of the orbital and size distribution of asteroids and comets in the inner Solar System, in order to refine the crater chronology method. Impact occurrences, locations, velocities and incidence angles are calculated semi-analytically, and scaling laws are used to convert impactor sizes into crater sizes. Our approach...
As Mercury orbits the Sun, gravitational torques on its equatorial elliptical shape give rise to a planetary libration. The amplitude of Mercury’s libration, as determined from Earth-based radar speckle pattern observations, suggests that only the mantle participates in the motion. This indicates a decoupling between the core and the mantle, and therefore that the outermost part of the core must be...
A 2-month series of quasi-simultaneous imaging photometric observations of the Moon and the Sun has been performed at Maidanak Observatory (Uzbekistan). New absolute values of lunar albedo have been obtained. Maps of lunar apparent albedo and equigonal albedo at phase angles 1.7–73° at wavelength 603nm are presented. The standard deviation of our data from a best-fitted phase curve is 2%. The average...
I have performed 3D numerical hydrodynamic simulations of impacts of stony projectiles on stony planar targets in a range of impact velocities from 1.25 to 60km/s. The projectile and target masses ejected at speeds greater than some given values have been calculated. This provided a possibility to determine impact erosion of a target which undergoes bombardment with comparatively small bodies. The...
A Large Program (LP) has been carried out at ESO–VLT using almost simultaneously the UT1, UT2 and UT4 telescopes (Cerro Paranal, Chile). The aim of this Large Program was to obtain simultaneous visible and near-IR spectroscopic measurements (using FORS, ISAAC and SINFONI instruments) with a S/N ratio as high as possible for almost all objects among different dynamical groups observable within the...
By using a hydrodynamic atmospheric escape mechanism (Levi, A., Podolak, M. [2009]. Icarus 202, 681–693) we show how the unusually high mass density of Quaoar could have been predicted (constrained), without any knowledge of a binary companion. We suggest an explanation of the recent spectroscopic observations of Orcus and Charon [Delsanti, A., Merlin, F., Guilbert, A., Bauer, J., Yang, B., Meech,...
A survey of 62 small near-Earth asteroids was conducted to determine the rotation state of these objects and to search for rapid rotation. Since results for 9 of the asteroids were previously published (Pravec, P., Hergenrother, C.W., Whiteley, R.J., Šarounová, L., Kušnirák, P., Wolf, M. [2000]. Icarus 147, 477–486; Pravec, P. et al. [2005] Icarus 173, 108–131; Whiteley, R.J., Tholen, D.J., Hergenrother,...
We present reflected light spectral observations from 0.4 to 2.5μm of 24 asteroids chosen from the population of asteroids initially classified as Tholen X-type objects (Tholen, 1984). The X complex in the Tholen taxonomy comprises the E, M and P classes which have very different inferred mineralogies but which are spectrally similar to each other, with featureless spectra in visible wavelengths.The...
A detailed theoretical study of the potential energy surface of H 2 CO 3 is explored at the CCSD(T)//B3LYP/aug-cc-pVTZ level. On the potential energy surface, 12 isomers of H 2 CO 3 are located. Their molecular properties such as geometries, vibrational frequencies, rotational constants, dipole moments, gas-phase acidities, and relative energies are calculated. Various...
Impact craters on planetary bodies transition with increasing size from simple, to complex, to peak-ring basins and finally to multi-ring basins. Important to understanding the relationship between complex craters with central peaks and multi-ring basins is the analysis of protobasins (exhibiting a rim crest and interior ring plus a central peak) and peak-ring basins (exhibiting a rim crest and an...
A mineralogical assessment of 3:1 Kirkwood Gap Asteroids (3760) Poutanen and (974) Lioba, has been carried out from spectral data obtained May 21, 2008 (974) and May 25, 2009 (3760) UT using the NASA Infrared Telescope Facility. Results indicate (3760) Poutanen as a spinel-bearing asteroid. The spinel contained within this asteroid appears to be embedded in calcium aluminum inclusions (CAIs) much...
Using model studies, the total gradient (TG) of the Z-component magnetic field is shown to be a useful quantity for delineating sources of satellite-altitude magnetic anomalies; this field is used to constrain the location and lateral boundaries of sources of high amplitude magnetic anomalies of southern highlands of Mars. The TG field suggests two parallel linear and oppositely magnetized sources...
The European Space Agency’s Rosetta spacecraft, en route to a 2014 encounter with comet 67P/Churyumov-Gerasimenko, made a gravity assist swing-by of Mars on 25 February 2007, closest approach being at 01:54UT. The Alice instrument on board Rosetta, a lightweight far-ultraviolet imaging spectrograph optimized for in situ cometary spectroscopy in the 750–2000Å spectral band, was used to study the daytime...
Fluvial features on Titan and drainage basins on Earth are remarkably similar despite differences in gravity and surface composition. We determined network bifurcation (R b ) ratios for five Titan and three terrestrial analog basins. Tectonically-modified Earth basins have R b values greater than the expected range (3.0–5.0) for dendritic networks; comparisons with R b values...
The detection of low-mass extrasolar planets has initiated growing interest in massive rocky bodies (super-Earths) for which no Solar System analogue does exist. Here, we present a new model approach to investigate their interior structure and thermal state. We improve and extend previous interior models mainly in two areas: the first improvement is due to the consequent application of equations of...
The Earth’s comparatively massive moon, formed via a giant impact on the proto-Earth, has played an important role in the development of life on our planet, both in the history and strength of the ocean tides and in stabilizing the chaotic spin of our planet. Here we show that massive moons orbiting terrestrial planets are not rare. A large set of simulations by Morishima et al. (Morishima, R., Stadel,...
A large, circular marking ∼1800km across is seen in near-infrared images of Titan. The feature is centered at 10°S, 120°W on Titan, encompasses much of Titan’s western Xanadu region, and has an off-center, quasi-circular, inner margin about 700km across, with lobate outer margins extending 200–500km from the inner margin. On the feature’s southern flank is Tui Regio, an area that has very high reflectivity...
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