Search Publications
Ongoing hydrothermal activities within Enceladus
Postberg, Frank; Altobelli, Nicolas; Sekine, Yasuhito +12 more
Detection of sodium-salt-rich ice grains emitted from the plume of the Saturnian moon Enceladus suggests that the grains formed as frozen droplets from a liquid water reservoir that is, or has been, in contact with rock. Gravitational field measurements suggest a regional south polar subsurface ocean of about 10 kilometres thickness located beneat…
The pH of Enceladus' ocean
Glein, Christopher R.; Waite, J. Hunter; Baross, John A.
Saturn's moon, Enceladus, is a geologically active waterworld. The prevailing paradigm is that there is a subsurface ocean that erupts to the surface, which leads to the formation of a plume of vapor and ice above the south polar region. The chemistry of the ocean is just beginning to be understood, but is of profound geochemical and astrobiologic…
GCM simulations of Titan's middle and lower atmosphere and comparison to observations
Lunine, Jonathan I.; Lora, Juan M.; Russell, Joellen L.
Simulation results are presented from a new general circulation model (GCM) of Titan, the Titan Atmospheric Model (TAM), which couples the Flexible Modeling System (FMS) spectral dynamical core to a suite of external/sub-grid-scale physics. These include a new non-gray radiative transfer module that takes advantage of recent data from Cassini-Huyg…
Effect of Enceladus's rapid synchronous spin on interpretation of Cassini gravity
McKinnon, William B.
Enceladus's degree 2 gravity, determined by Cassini, is nominally nonhydrostatic to 3σ (J2/C22 = 3.38-3.63, as opposed to 10/3). Iess et al. (2014) interpret this in terms of a hydrostatic interior (core) and isostatic (not hydrostatic) floating ice shell. Enceladus's rapid (1.37 d) synchronous spin and tide distorts its shap…
Seasonal variations in Titan's middle atmosphere during the northern spring derived from Cassini/CIRS observations
Bézard, Bruno; Vinatier, Sandrine; Achterberg, Richard K. +8 more
We analyzed spectra acquired at the limb of Titan in the 2006-2013 period by the Cassini/Composite Infrared Spectrometer (CIRS) in order to monitor the seasonal evolution of the thermal, gas composition and aerosol spatial distributions. We are primarily interested here in the seasonal changes after the northern spring equinox and interpret our re…
Field-aligned currents in Saturn's northern nightside magnetosphere: Evidence for interhemispheric current flow associated with planetary period oscillations
Coates, A. J.; Dougherty, M. K.; Alexeev, I. I. +6 more
We investigate the magnetic perturbations associated with field-aligned currents observed on 34 Cassini passes over the premidnight northern auroral region during 2008. These are found to be significantly modulated not only by the northern planetary-period oscillation (PPO) system, similar to the southern currents by the southern PPO system found …
Nature of the MHD and Kinetic Scale Turbulence in the Magnetosheath of Saturn: Cassini Observations
Dougherty, M. K.; Sahraoui, F.; Masters, A. +5 more
Low-frequency turbulence in Saturn’s magnetosheath is investigated using in situ measurements of the Cassini spacecraft. Focus is put on the magnetic energy spectra computed in the frequency range of ∼[10-4, 1]Hz. A set of 42 time intervals in the magnetosheath were analyzed, and three main results that contrast with known features of s…
Structural mapping of Enceladus and implications for formation of tectonized regions
Crow-Willard, Emma N.; Pappalardo, Robert T.
Global structural mapping of high-resolution Cassini images of Enceladus reveals a richly varied surface. Most notable are three main regions of deformation each containing multiple structural units. In addition to the well known "South Polar Terrain" (SPT), there are two other large regions of deformation that we term "Leading Hemisphere Terrain"…
Curtain eruptions from Enceladus' south-polar terrain
Spitale, Joseph N.; Hurford, Terry A.; Rhoden, Alyssa R. +2 more
Observations of the south pole of the Saturnian moon Enceladus revealed large rifts in the south-polar terrain, informally called `tiger stripes', named Alexandria, Baghdad, Cairo and Damascus Sulci. These fractures have been shown to be the sources of the observed jets of water vapour and icy particles and to exhibit higher temperatures than the …
Possible evidence for a methane source in Enceladus' ocean
Mousis, Olivier; Bouquet, Alexis; Waite, J. Hunter +1 more
The internal ocean of Enceladus can be expected to present conditions favorable to the trapping of volatiles in clathrates. This process could influence the eventual composition of the ocean and therefore of the plumes emitted by the south polar region. Here we used a statistical thermodynamic model to assess which species detected in the plumes b…