Search Publications
Ion densities and composition of Titan's upper atmosphere derived from the Cassini Ion Neutral Mass Spectrometer: Analysis methods and comparison of measured ion densities to photochemical model simulations
Edberg, Niklas J. T.; Liang, Mao-Chang; Mandt, Kathleen E. +16 more
The Cassini Ion Neutral Mass Spectrometer (INMS) has measured both neutral and ion species in Titan's upper atmosphere and ionosphere and the Enceladus plumes. Ion densities derived from INMS measurements are essential data for constraining photochemical models of Titan's ionosphere. The objective of this paper is to present an optimized method fo…
Influence of temperature, composition, and grain size on the tensile failure of water ice: Implications for erosion on Titan
Litwin, Kimberly L.; Zygielbaum, Beth R.; Polito, Peter J. +2 more
Ice resistance to tensile fracture influences surface morphodynamics on outer planetary satellites such as Titan, yet measurements of tensile strength and fracture toughness of polycrystalline water ice at temperatures below terrestrial conditions (<220 K) have not been previously reported. We investigated these parameters from 260 K to 110 K u…
The roles of charge exchange and dissociation in spreading Saturn's neutral clouds
Delamere, P. A.; Bagenal, F.; Fleshman, B. L. +1 more
Neutrals sourced directly from Enceladus's plumes are initially confined to a dense neutral torus in Enceladus's orbit around Saturn. This neutral torus is redistributed by charge exchange, impact/photodissociation, and neutral-neutral collisions to produce Saturn's neutral clouds. Here we consider the former processes in greater detail than in pr…
The CH4 structure in Titan's upper atmosphere revisited
Strobel, D. F.; Galand, M.; Yelle, R. V. +4 more
In this study, we reanalyze the CH4 structure in Titan's upper atmosphere combining the Cassini Ion Neutral Mass Spectrometer (INMS) data from 32 flybys and incorporating several updates in the data reduction algorithms. We argue that based on our current knowledge of eddy mixing and neutral temperature, strong CH4 escape mus…
Titan's ionospheric composition and structure: Photochemical modeling of Cassini INMS data
Wahlund, J. -E.; Magee, B. A.; Mandt, K. E. +4 more
Titan's upper atmosphere produces an ionosphere at high altitudes from photoionization and electron impact that exhibits complex chemical processes in which hydrocarbons and nitrogen-containing molecules are produced through ion-molecule reactions. The structure and composition of Titan's ionosphere has been extensively investigated by the Ion and…
Estimating erosional exhumation on Titan from drainage network morphology
Black, Benjamin A.; Perron, J. Taylor; Burr, Devon M. +1 more
Drainage networks on Titan, Earth, and Mars provide the only known examples of non-volcanic fluvial activity in our solar system. The drainage networks on Titan are apparently the result of a methane-ethane cycle similar to Earth's water cycle. The scarcity of impact craters and the uneven distribution of fluvial dissection on Titan suggest that t…
Emitted power of Jupiter based on Cassini CIRS and VIMS observations
West, Robert A.; Baines, Kevin H.; Nixon, Conor A. +11 more
The emitted power of Jupiter and its meridional distribution are determined from observations by the Composite Infrared Spectrometer and Visual and Infrared Mapping Spectrometer onboard Cassini during its flyby en route to Saturn in late 2000 and early 2001. Jupiter's global-average emitted power and effective temperature are measured to be 14.10 …
Edge detection applied to Cassini images reveals no measurable displacement of Ontario Lacus' margin between 2005 and 2010
Sotin, Christophe; Barnes, Jason W.; Le Mouélic, Stéphane +8 more
Ontario Lacus is thus far the largest flat-floored topographic depression of Titan's southern hemisphere interpreted as a permanent or ephemeral lake. From 2005 to 2010, it was imaged several times and at various wavelengths by ISS, VIMS and RADAR instruments onboard Cassini's spacecraft. We analyze the position and uncertainty of Ontario Lacus' m…
On the application of simple rift basin models to the south polar region of Enceladus
Liemohn, M. W.; Walker, C. C.; Bassis, J. N.
The south polar terrain (SPT) of Saturn's moon Enceladus is a mysteriously active region that exhibits intriguing tectonic signatures and widespread fracturing. The central region of the nearly-circular SPT is depressed into the surface by a few hundred meters and bounded by a ring of cliffs roughly 1 km high. In this study, we investigate whether…