Search Publications
Geomorphologic mapping of the Menrva region of Titan using Cassini RADAR data
Lopes, Rosaly M. C.; Williams, David A.; Radebaugh, Jani +1 more
We made a detailed geomorphologic map of the Menrva region of Titan, using Cassini RADAR data as our map base. Using similar techniques and approaches that were applied to mapping Magellan radar images of Venus, and earlier, more generalized Titan maps, we were able to define and characterize 10 radar morphologic units, along with inferred dunes a…
Neptune's cloud and haze variations 1994-2008 from 500 HST-WFPC2 images
Karkoschka, Erich
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 ∼5 years.…
The Christiansen Effect in Saturn's narrow dusty rings and the spectral identification of clumps in the F ring
Sotin, C.; Brown, R. H.; Buratti, B. J. +5 more
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 aro…
Analysis of Titan CH 4 3.3 µm upper atmospheric emission as measured by Cassini/VIMS
Funke, Bernd; García-Comas, Maya; Coradini, Angioletta +5 more
After molecular nitrogen, methane is the most abundant species in Titan's atmosphere and plays a major role in its energy budget and its chemistry. Methane has strong bands at 3.3 µm emitting mainly at daytime after absorption of solar radiation. This emission is strongly affected by non-local thermodynamic equilibrium (non-LTE) in Titan's u…
Cassini VIMS observations of latitudinal and hemispheric variations in Saturn’s infrared auroral intensity
Baines, Kevin H.; Kasahara, Satoshi; Brown, Robert H. +6 more
The intensity of Saturn’s infrared H3+ aurora is investigated using Cassini VIMS images acquired during October 2006-February 2009. Polar and main oval auroral regions were defined in both hemispheres, which extend between 0-10° and 10-25° co-latitude, respectively. Average intensities were computed for these regions and compared. While the northe…
The Kelvin-Helmholtz instability at Venus: What is the unstable boundary?
Lammer, Helmut; Gröller, Hannes; Möstl, Ute V. +4 more
The Kelvin-Helmholtz instability gained scientific attention after observations at Venus by the spacecraft Pioneer Venus Orbiter gave rise to speculations that the instability contributes to the loss of planetary ions through the formation of plasma clouds. Since then, a handful of studies were devoted to the Kelvin-Helmholtz instability at the io…
Retrieving optical depth from shadows in orbiter images of Mars
Keller, H. U.; Thomas, N.; Hoekzema, N. M. +6 more
The difference in brightness between shadowed and sunlit regions in space images of Mars is a measure of the optical depth of the atmosphere. The translation of this difference into optical depth is what we name the "shadow method". Our analysis of two HRSC data-sets and a HiRISE data-set indicates that it is possible to estimate the optical depth…
Channel morphometry, sediment transport, and implications for tectonic activity and surficial ages of Titan basins
Kirk, Randolph L.; Cartwright, Richard; Clayton, Jordan A.
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) …
Analytical description of physical librations of saturnian coorbital satellites Janus and Epimetheus
Robutel, Philippe; Rambaux, Nicolas; Castillo-Rogez, Julie
Janus and Epimetheus are famously known for their distinctive horseshoe-shaped orbits resulting from a 1:1 orbital resonance. Every 4 years these two satellites swap their orbits by a few tens of kilometers as a result of their close encounter. Recently Tiscareno et al. (Tiscareno, M.S., Thomas, P.C., Burns, J.A. [2009]. Icarus 204, 254-261) have …
Secondary chaotic terrain formation in the higher outflow channels of southern circum-Chryse, Mars
Fairén, Alberto G.; Kargel, Jeffrey S.; Baker, Victor R. +7 more
Higher outflow channel dissection in the martian region of southern circum-Chryse appears to have extended from the Late Hesperian to the Middle Amazonian Epoch. These outflow channels were excavated within the upper 1 km of the cryolithosphere, where no liquid water is expected to have existed during these geologic epochs. In accordance with prev…