Search Publications
Oxygen ion escape at Mars in a hybrid model: High energy and low energy ions
Jarvinen, Riku; Kallio, Esa; Janhunen, Pekka +2 more
We have studied the escape and energization of several O+ populations and an O2+ population at Mars by using a hybrid model. The quasi-neutral hybrid model, HYB-Mars model, included five oxygen ion populations making it possible to distinguish photoions from oxygen ions originating from charge exchange processes and from the ionosphere.…
Clouds on Titan during the Cassini prime mission: A complete analysis of the VIMS data
Brown, Michael E.; Schaller, Emily L.; Roberts, Jessica E.
We use data from the VIMS instrument on board the Cassini spacecraft to construct high sensitivity and high spatial-resolution maps of the locations of tropospheric clouds on Titan in the late northern winter season during which the Cassini prime mission took place. These observations show that, in this season, clouds on Titan are strongly hemisph…
Analysis of phyllosilicate deposits in the Nili Fossae region of Mars: Comparison of TES and OMEGA data
Mangold, Nicolas; Bibring, Jean-Pierre; Poulet, François +1 more
Diverse phyllosilicate deposits discovered previously in the Nili Fossae region with near infrared reflectance data are a window into the complex history of aqueous alteration on Mars. In this work, we used thermal infrared data from the Thermal Emission Spectrometer (TES) in combination with near infrared data from the Observatoire pour la Minéra…
Distribution and evolution of scalloped terrain in the southern hemisphere, Mars
Reiss, Dennis; Neukum, Gerhard; Hauber, Ernst +2 more
Scalloped depressions are a unique martian surface morphology found in the northern and southern hemisphere latitude-dependent dust and ice-rich surface mantles. These features exhibit a distinct asymmetric north-south slope profile, characterized by steep pole-facing scarps, flat floors and gentle equator-facing slopes. We examined High Resolutio…
Radar-bright channels on Titan
Lorenz, R. D.; Janssen, M. A.; Cassini RADAR Team +3 more
During Cassini's T44 flyby of Titan (May 28, 2008), the Cassini SAR (synthetic aperture radar) revealed sinuous channels in the Southwest of Xanadu. These channels feature very large radar cross-sections, up to 5 dB, whereas the angle of incidence was relatively high, ∼20°. This backscatter is larger than allowed by the coherent backscatter model …
Molecular hydrogen in Titan’s atmosphere: Implications of the measured tropospheric and thermospheric mole fractions
Strobel, Darrell F.
The third most abundant species in Titan's atmosphere is molecular hydrogen with a tropospheric/lower stratospheric mole fraction of 0.001 derived from Voyager and Cassini infrared measurements. The globally averaged thermospheric H mole fraction profile from the Cassini Ion Neutral Mass Spectrometer (INMS) measurements implies a small positive gr…
Geology of the Selk crater region on Titan from Cassini VIMS observations
Nicholson, Philip D.; Sotin, Christophe; Barnes, Jason W. +9 more
Observations of Titan obtained by the Cassini Visual and Infrared Mapping Spectrometer (VIMS) have revealed Selk crater, a geologically young, bright-rimmed, impact crater located ∼800 km north-northwest of the Huygens landing site. The crater rim-crest diameter is ∼90 km; its floor diameter is ∼60 km. A central pit/peak, 20-30 km in diameter, is …
The ultraviolet reflectance of Enceladus: Implications for surface composition
Hendrix, Amanda R.; Hansen, Candice J.; Holsclaw, Greg M.
The reflectance of Saturn's moon Enceladus has been measured at far ultraviolet (FUV) wavelengths (115-190 nm) by Cassini's Ultraviolet Imaging Spectrograph (UVIS). At visible and near infrared (VNIR) wavelengths Enceladus' reflectance spectrum is very bright, consistent with a surface composed primarily of H 2O ice. At FUV wavelengths,…
Dayside induced magnetic field in the ionosphere of Mars
Gurnett, D. A.; Morgan, D. D.; Modolo, R. +5 more
The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) onboard the Mars Express spacecraft has occasionally displayed surprising features. One such feature is the occurrence of a series of broadband, low-frequency echoes at equally spaced delay times after the sounder transmitter pulse. The interval between the echoes has been sh…
Estimating the masses of Saturn’s A and B rings from high-optical depth N-body simulations and stellar occultations
Colwell, Joshua E.; Sremčević, Miodrag; Robbins, Stuart J. +2 more
We have completed a series of local N-body simulations of Saturn's B and A rings in order to identify systematic differences in the degree of particle clumping into self-gravity wakes as a function of orbital distance from Saturn and dynamical optical depth (a function of surface density). These simulations revealed that the normal optical depth o…