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The geological history of Northeast Syrtis Major, Mars
Mustard, John F.; Bramble, Michael S.; Salvatore, Mark R.
As inferred from orbital spectroscopic data, Northeast Syrtis Major bears considerable mineral diversity that spans the Noachian-Hesperian boundary despite its small geographic area. In this study we use observations from the High Resolution Imaging Science Experiment, supplemented with Context Camera imagery, to characterize and map the lateral e…
Sulfur dioxide in the Venus atmosphere: I. Vertical distribution and variability
Vandaele, A. C.; Robert, S.; Montmessin, F. +18 more
Recent observations of sulfur containing species (SO2, SO, OCS, and H2SO4) in Venus' mesosphere have generated controversy and great interest in the scientific community. These observations revealed unexpected spatial patterns and spatial/temporal variability that have not been satisfactorily explained by models. S…
True polar wander of Enceladus from topographic data
Hedman, Matthew M.; Schenk, Paul M.; Burns, Joseph A. +4 more
Many objects in the solar system are suspected to have experienced reorientation of their spin axes. As their rotation rates are slow and their shapes are nearly spherical, the formation of mass anomalies, by either endogenic or exogenic processes, can change objects' moments of inertia. Therefore, the objects reorient to align their largest momen…
Impact crater relaxation on Dione and Tethys and relation to past heat flow
Schenk, Paul M.; White, Oliver L.; Bray, Veronica J. +3 more
Relating relaxation of impact crater topography to past heat flow through the crusts of icy satellites is a technique that has been applied to satellites around Jupiter and Saturn. We use global digital elevation models of the surfaces of Dione and Tethys generated from Cassini data to obtain crater depth/diameter (d/D) data. Relaxation is found t…
Exposure age of Saturn's A and B rings, and the Cassini Division as suggested by their non-icy material content
Nicholson, P. D.; Janssen, M. A.; Hayes, A. G. +4 more
Saturn's rings are composed primarily of water ice with a small fraction of non-icy constituents that are likely both intrinsic and extrinsic in origin. The intrinsic material is thought to be characteristic of the ring progenitor, while the extrinsic material is derived from the continual stream of hypervelocity impacting micrometeoroids that pol…
Sulfur dioxide in the Venus Atmosphere: II. Spatial and temporal variability
Vandaele, A. C.; Robert, S.; Montmessin, F. +18 more
The vertical distribution of sulfur species in the Venus atmosphere has been investigated and discussed in Part I of this series of papers dealing with the variability of SO2 on Venus. In this second part, we focus our attention on the spatial (horizontal) and temporal variability exhibited by SO2. Appropriate data sets - SPI…
Compositional and structural constraints on the geologic history of eastern Tharsis Rise, Mars
Murchie, S. L.; Viviano-Beck, C. E.; Beck, A. W. +1 more
Identification and mapping of distinct compositional units using high-resolution orbital imagery of the walls of Valles Marineris, Mars, provide key structural and environmental constraints on the geologic history of the eastern Tharsis Rise. Our results corroborate an overall vertical structure of the upper crust consistent with that inferred fro…
Thermal structure of the upper atmosphere of Venus simulated by a ground-to-thermosphere GCM
López-Valverde, M. A.; Gilli, G.; González-Galindo, F. +5 more
We present here the thermal structure of the upper atmosphere of Venus predicted by a full self-consistent Venus General Circulation Model (VGCM) developed at Laboratoire de Météorologie Dynamique (LMD) and extended up to the thermosphere of the planet. Physical and photochemical processes relevant at those altitudes, plus a non-orographic GW para…
The thermal structure of the Venus atmosphere: Intercomparison of Venus Express and ground based observations of vertical temperature and density profiles✰
Montmessin, Franck; Tanga, Paolo; Tellmann, Silvia +30 more
The Venus International Reference Atmosphere (VIRA) model contains tabulated values of temperature and number densities obtained by the experiments on the Venera entry probes, Pioneer Venus Orbiter and multi-probe missions in the 1980s. The instruments on the recent Venus Express orbiter mission generated a significant amount of new observational …
Mars sedimentary rock erosion rates constrained using crater counts, with applications to organic-matter preservation and to the global dust cycle
Kite, Edwin S.; Mayer, David P.
Small-crater counts on Mars light-toned sedimentary rock are often inconsistent with any isochron; these data are usually plotted then ignored. We show (using an 18-HiRISE-image, > 104-crater dataset) that these non-isochron crater counts are often well-fit by a model where crater production is balanced by crater obliteration via ste…