Search Publications
How the Geysers, Tidal Stresses, and Thermal Emission across the South Polar Terrain of Enceladus are Related
Nimmo, Francis; Porco, Carolyn; DiNino, Daiana
We present the first comprehensive examination of the geysering, tidal stresses, and anomalous thermal emission across the south pole of Enceladus and discuss the implications for the moon's thermal history and interior structure. A 6.5 yr survey of the moon's south polar terrain (SPT) by the Cassini imaging experiment has located ~100 jets or gey…
The bathymetry of a Titan sea
Paillou, Philippe; Zebker, Howard; Lunine, Jonathan +9 more
We construct the depth profile—the bathymetry—of Titan's large sea Ligeia Mare from Cassini RADAR data collected during the 23 May 2013 (T91) nadir-looking altimetry flyby. We find the greatest depth to be about 160 m and a seabed slope that is gentler toward the northern shore, consistent with previously imaged shoreline morphologies. Low radio s…
Constraints on modified Newtonian dynamics theories from radio tracking data of the Cassini spacecraft
Jacobson, R. A.; Folkner, W. M.; Hees, A. +1 more
The modified Newtonian dynamics (MOND) is an attempt to modify the gravitation theory to solve the dark matter problem. This phenomenology is very successful at the galactic level. The main effect produced by MOND in the Solar System is called the external field effect parametrized by the parameter Q2. We have used nine years of Cassini…
Saturn ring seismology: Evidence for stable stratification in the deep interior of Saturn
Fuller, Jim
Seismology allows for direct observational constraints on the interior structures of stars and planets. Recent observations of Saturn's ring system have revealed the presence of density waves within the rings excited by oscillation modes within Saturn, allowing for precise measurements of a limited set of the planet's mode frequencies. We construc…
Chemical composition of Titan’s atmosphere and ionosphere: Observations and the photochemical model
Krasnopolsky, Vladimir A.
Basic observational data on hydrocarbons, nitriles, and ions on Titan are compared with predictions of the photochemical model. Uncertainties of the observed abundances and differences between the data from different instruments and observing teams are comparable with the differences between the observations and the model results. Main reactions o…
Field-aligned currents in Saturn's southern nightside magnetosphere: Subcorotation and planetary period oscillation components
Coates, A. J.; Dougherty, M. K.; Alexeev, I. I. +6 more
We investigate magnetic data showing the presence of field-aligned magnetosphere-ionosphere coupling currents on 31 Cassini passes across Saturn's southern postmidnight auroral region. The currents are strongly modulated in magnitude, form, and position by the phase of the southern planetary period oscillations (PPOs). PPO-independent currents are…
Shape, topography, gravity anomalies and tidal deformation of Titan
Lunine, Jonathan I.; Hayes, Alex; Zebker, Howard +5 more
Gravity measurements and elevation data from the Cassini mission have been used to create shape, global topography and gravity anomaly models of Titan that enable an improved understanding of its outer ice I shell structure. We provide constraints on the averaged ice shell thickness and its long-wavelength lateral variations, as well as the densit…
Coupling of oxygen, nitrogen, and hydrocarbon species in the photochemistry of Titan's atmosphere
Dobrijevic, M.; Loison, J. C.; Hickson, K. M. +1 more
Analysis of recent detections of water by Herschel/HIFI-PACS and Cassini/CIRS suggest for a steep gradient of the water profile in the lower stratosphere of Titan's atmosphere (Cottini, V., Nixon, C.A., Jennings, D.E., Anderson, C.M., Gorius, N., Bjoraker, G.L., Coustenis, A., Teanby, N.A., Achterberg, R.K., Béezard, B., de Kok, R., Lellouch, E., …
Tidally Modulated Eruptions on Enceladus: Cassini ISS Observations and Models
Nimmo, Francis; Porco, Carolyn; Mitchell, Colin
We use images acquired by the Cassini Imaging Science Subsystem (ISS) to investigate the temporal variation of the brightness and height of the south polar plume of Enceladus. The plume's brightness peaks around the moon's apoapse, but with no systematic variation in scale height with either plume brightness or Enceladus' orbital position. We comp…
Titan’s internal structure inferred from its gravity field, shape, and rotation state
Tobie, Gabriel; Lefèvre, Axel; Baland, Rose-Marie +1 more
Several quantities measured by the Cassini-Huygens mission provide insight into the interior of Titan: the second-degree gravity field coefficients, the shape, the tidal Love number, the electric field, and the orientation of its rotation axis. The measured obliquity and tides, as well as the electric field, are evidence for the presence of an int…