Search Publications
A diffuse core in Saturn revealed by ring seismology
Fuller, Jim; Mankovich, Christopher R.
The best constraints on the internal structures of giant planets have historically originated from measurements of their gravity fields1-3. These data are inherently mostly sensitive to a planet's outer regions, stymieing efforts to measure the mass and compactness of the cores of Jupiter2,4,5 and Saturn6,7. Howeve…
Bayesian analysis of Enceladus's plume data to assess methanogenesis
Affholder, Antonin; Guyot, François; Sauterey, Boris +2 more
Observations from NASA's Cassini spacecraft established that Saturn's moon Enceladus has an internal liquid ocean. Analysis of a plume of ocean material ejected into space suggests that alkaline hydrothermal vents are present on Enceladus's seafloor. On Earth, such deep-sea vents harbour microbial ecosystems rich in methanogenic archaea. Here we u…
Constraining Saturn's Interior with Ring Seismology: Effects of Differential Rotation and Stable Stratification
Fuller, Jim; Lai, Dong; Dewberry, Janosz W. +2 more
Normal mode oscillations in Saturn excite density and bending waves in the C ring, providing a valuable window into the planet's interior. Saturn's fundamental modes (f-modes) excite the majority of the observed waves, while gravito-inertial modes (rotationally modified g-modes) associated with stable stratification in the deep interior provide a …
Potential vorticity structure of Titan's polar vortices from Cassini CIRS observations
Nixon, Conor A.; Irwin, Patrick G. J.; Teanby, Nicholas A. +4 more
The Cassini mission has provided the best opportunity to date to extensively study the seasonal variation in Titan's atmosphere, with observations spanning almost half a Titan year (Ls = 293 - 93 °). An important feature in the Titan middle-atmosphere is the formation of a polar vortex. Observations have shown that an initially well-dev…
Jupiter's Auroral Radio Emissions Observed by Cassini: Rotational Versus Solar Wind Control, and Components Identification
Cecconi, B.; Lamy, L.; Zarka, P. +5 more
Reanalyzing Cassini radio observations performed during Jupiter's flyby of 2000-2001, we study the internal (rotational) versus external (solar wind) control of Jupiter's radio emissions, from kilometer to decameter wavelengths, and the relations between the different auroral radio components. For that purpose, we build a database of the occurrenc…
Haze Seasonal Variations of Titan's Upper Atmosphere during the Cassini Mission
West, Robert A.; Vinatier, Sandrine; Seignovert, Benoît +1 more
This study presents a 13 yr survey of haze UV extinction profiles, monitoring the temporal evolution of the detached haze layer (DHL) in Titan's upper atmosphere (350-600 km). As reported by West et al. (GRL vol.38, L06204) at the equator, we show that the DHL was present at all latitudes below 55°N during the northern winter (2004-2009). Subseque…
Flux Transfer Events at a Reconnection Suppressed Magnetopause: Cassini Observations at Saturn
Coates, Andrew J.; Fuselier, Stephen A.; Slavin, James A. +5 more
We present the discovery of seven new flux transfer events (FTEs) at Saturn's dayside magnetopause by the Cassini spacecraft and analyze the observations of all eight known FTEs. We investigate how FTEs may differ at Saturn where the magnetopause conditions are likely to diamagnetically suppress magnetic reconnection from occurring. The measured i…
Empirical Selection of Auroral Kilometric Radiation During a Multipoint Remote Observation With Wind and Cassini
Jackman, C. M.; Bonnin, X.; Cecconi, B. +5 more
Auroral Kilometric Radiation (AKR) is terrestrial radio emission that originates in particle acceleration regions along magnetic field lines, coinciding with discrete auroral arcs. AKR viewing geometry is complex due to the confinement of the source regions to nightside local times (LTs) and the anisotropy of the beaming pattern, so observations a…
Cassini Observation of Relativistic Electron Butterfly Distributions in Saturn's Inner Radiation Belts: Evidence for Acceleration by Local Processes
Krupp, N.; Wei, Y.; Roussos, E. +3 more
The morphology of electron pitch angle distributions (PADs) helps to identify dynamic processes in Saturn's magnetosphere. Previous studies demonstrated convective transport being important for relativistic electron acceleration at L > 4 in the inner magnetosphere, whereas closer to Saturn the situation is not as well established. We have inves…
Sampling Plume Deposits on Enceladus' Surface to Explore Ocean Materials and Search for Traces of Life or Biosignatures
Malaska, Michael J.; Choukroun, Mathieu; Backes, Paul +14 more
Enceladus is unique as an astrobiology target in that it hosts an active plume sourced directly from its habitable subsurface ocean. Ice particles from the plume contain geochemical constituents that are diagnostic of the ocean conditions, and may hold traces of life and/or biosignatures, if they exist. Up to 93% of the plume particles fall back o…